Tag Archives: yeast

A 6,000-year-old fruit fly gave the world modern cheeses and yogurts

Credit: Pixabay.

Historians often trace the dawn of human civilisation back 10,000 years, when Neolithic tribes first settled and began farming in the Fertile Crescent, which stretches through much of what we now call the Middle East. Prehistoric peoples domesticated plants to create the cereal crops we still grow today, and in the Zagros mountains of Iran, Iraq and Turkey, sheep, goats and cows were bred from their wild relatives to ensure a steady supply of meat and milk. But around the same time as plants and animals were tamed for agriculture, long before anyone even knew of microscopic life, early humans were domesticating microbes too.

In a paper published in Current Biology, we discovered how “milk yeast” – the handy microorganism that can decompose lactose in milk to create dairy products like cheese and yoghurt – originated from a chance encounter between a fruit fly and a pail of milk around 5,500 years ago. This happy accident allowed prehistoric people to domesticate yeast in much the same way they domesticated crop plants and livestock animals, and produce the cheeses and yogurts billions of people enjoy today.

Milk yeast cells are large and oval and here surrounded by rod-shaped bacterial cells. Loughlin Gethins & Suzanne Crotty, UCC, Author provided

The domesticated diet

Domestication is evolution directed by a human hand. After wild parents have bred, farmers retain the offspring with properties that are beneficial for future breeding. Take farmed wheat, for example. This crop species produces a lot more seeds than wild grasses do, because these seeds are the grain that humans harvest. Early farmers deliberately bred pairs of wheat plants that produced lots of grain so that their offspring would inherit this trait. As these pairings were repeated over many generations, grain-rich descendants were gradually created.

It’s survival of the fittest, but the fittest are variants that have characteristics that are useful for humans. The wary and vicious wolf becomes the friendly and obedient dog.

Neolithic farmers stumbled on the practice of domesticating microbes when they tried to preserve food by fermenting it. Fermentation relies on microbes, such as bacteria, yeast and fungi, increasing the acidity of the food to protect it against spoilage. Microbes that were good at making fermented products that were palatable and safe were kept to start the next batch, and so useful microbes were evolved and domesticated. “Baker’s yeast,” or Saccharomyces cerevisiae, was a microbe selected from nature to make beer, wine and other fermented drinks 13,000 years ago.

Kluyveromyces lactis, or milk yeast, is found in French and Italian cheeses made from unpasteurised milk, and in natural fermented dairy drinks like kefir. But the ancestor of this microbe was originally associated with the fruit fly, so how did it end up making many of the dairy products that people eat today? We believe milk yeast owes its very existence to a fly landing in fermenting milk and starting an unusual sexual liaison. The fly in question was the common fruit fly, Drosophila, and it carried with it the ancestor of K. lactis. Although the fly died, the yeast lived, but with a problem – it could not use the lactose in milk as a food source. Instead, it found an unconventional solution – sex with its cousin.

When K. lactis arrived with the fly, its cousin K. marxianus was already happily growing in the milk. K. marxianus is able to use lactose for growth because it has two extra proteins which can help break down lactose into simple sugars that it then uses for energy. The cousins reproduced and the genes needed to use lactose transferred from K. marxianus to K. lactis. The end result was that K. lactis acquired two new genes and could then grow on lactose and survive on its own. The fermented product that K. lactis made must have been particularly delicious as it was used to start a new fermentation – a routine that has continued to the present day.

We think that by 6,000 years ago, farmers were using fermented goat and sheep milk to make tasty beverages like yoghurt and kefir. We know that milk-producing animals – cows, sheep, goats – were all domesticated between 8,000 and 10,000 years ago, and analysis of human tartar found on teeth shows that humans were consuming milk, most likely as cheese or other fermented products by 5,500 years ago. The chance encounter between two yeast species and a little bit of illicit sex made all of this possible.

Who could’ve imagined that such a random series of events would produce so many of the world’s great culinary delicacies?

John Morrissey, Lecturer in Microbiology, University College Cork

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How one thumb injury led to one man getting drunk from eating carbs

A recent case study recounts the story of one man getting drunk from pizzas, sodas, and everything in between.

Perhaps the coolest sounding medical complication ever, auto-brewery syndrome (ABS) is a rarely-diagnosed condition where patients can get very drunk when eating carbohydrates (the much-bemoaned ‘carbs’). And, at least in the case of one 46-year-old patient, ABS can cause some social tensions when nobody believes you haven’t been drinking when a plate of pasta leaves you staggering.

Involuntarily inebriated

The case study looks at a patient that had completed a course of antibiotics for a thumb injury in 2011. One week after the treatment, he reported to the doctor’s office citing uncharacteristic personality changes such as depression, ‘brain fog’, aggressive behavior, and memory loss.

He was at one point referred to a psychiatrist and given antidepressants. However, the nature of his condition wasn’t fully understood until he was pulled over by police one morning in an apparent case of drunk driving. At the time, he refused to take a breathalyzer test, as he knew for a fact that he didn’t drink any alcohol. The officer had him hospitalized for a blood test. This showed the patient had a blood-alcohol level of 200 mg/dL, equivalent to having drunk approximately 10 pints of beer, and enough to cause confusion, disorientation, impaired balance, and slurred speech.

“The hospital personnel and police refused to believe him when he repeatedly denied alcohol ingestion,” researchers from Richmond University Medical Centre note in their case report.

Subsequent medical tests found Saccharomyces cerevisiae (brewer’s yeast) and a related fungus in the patient’s stool. S. cervisiae is used in brewing as it breaks down sugars in plants into alcohol. While he was successfully treated, later flare-ups of the same condition — with the most serious incident involving a fall while inebriated that caused intracranial bleeding — led to him being diagnosed with ABS.

The researchers note that while recovering in the hospital, the patient’s blood alcohol spiked as high as 400 mg/dL. Still, “medical staff refused to believe that he did not drink alcohol despite his persistent denials”. Ultimately, the patient received treatment conducted in collaboration with the Richmond University specialists; the team used a cocktail of anti-fungal therapies supported by probiotics to reset his gut microflora. With the exception of one relapse when the patient sneakily enjoyed some pizza and soda without telling his doctors, the fungal infection has been successfully treated, the team explains.

“Approximately 1.5 years later, he remains asymptomatic and has resumed his previous lifestyle, including eating a normal diet while still checking his breath alcohol levels sporadically,” the researchers explain.

It’s a happy ending for the patient, who looks to be finally free not only of his unasked-for drunkenness (and resultant health problems) but also of the cloud of disbelief it invited in those around him.

“For years, no one believed him,” says Fahad Malik, a chief medical resident at the University of Alabama at Birmingham and the lead author of the case study. “The police, doctors, nurses and even his family told him he wasn’t telling the truth, that he must be a closet-drinker.”

“We believe that our patient’s symptoms were triggered by exposure to antibiotics, which resulted in a change in his gastrointestinal microbiome allowing fungal overgrowth,” the authors explain, noting that we are only starting to recognise the complexity of this rare and probably under-diagnosed condition.

The paper “Case report and literature review of auto-brewery syndrome: probably an underdiagnosed medical condition” has been published in the journal BMJ Open Gastroenterology.

Yeast bags.

Asia may have given the world beer yeast, new research finds

A novel study into the historical origins of beer yeast finds that it likely emerged via an East-West transfer, probably through avenues such as the Silk Route.

Yeast bags.

Image via Pixabay.

The yeast fermenting your beer right now is a mixture of European grape wine and Asian rice wine strains, new research reports. The findings come from a study of the historical origins of brewer’s yeast — which is still poorly understood despite its economic significance — and points to the emergence of beer yeast from a historical East-West transfer of fermentation technology, similar to the transfer of domesticated plants and animals by way of the Silk Route.

An international product

“We conclude that modern beer strains are the product of a historical melting pot of fermentation technology,” the authors explain in the study’s abstract.

Pinpointing the origins of domesticated yeast is not an easy feat. Yeast has been taken along by humans on countless migrations (some recent, others ancient), which mixed its genes quite a lot, and in an unpredictable manner. It’s also made more difficult by a lack of genetic material. Archeologists and anthropologists draw on DNA to date and reconstruct many of the events they’re studying, but they can’t do that with yeast. We simply don’t have suitable samples of ancient fermented beverages from which to draw the microbes used in their production.

The team of the present study turned to beer yeast because one of its characteristics gave them a chance to work around these issues. Many strains of beer yeast are polyploid — the nuclei in their cells have more than two copies of their genome. The team hoped that this abundance of genetic material allowed different strains to remain isolated from other populations, effectively providing a living relic of their ancestors’ DNA.

In order to try and piece together the history of beer yeast, the team sequenced and compared the genomes of different beer yeast strains from around the world. These beer yeast strains formed four related groups, according to the team: two for ales, one for lager, and one which contained both beer and baking yeasts.

All groups showed a mixed ancestry of European grape wine and Asian rice wine strains, with some novel genes (not found in any other populations of yeast) peppered in. The origin of these final genes is still unclear, but judging by their number — they’re quite abundant — the team believes they may have originated in a now-extinct strain (or maybe a living population whose genome has yet to be sequenced).

Piecing together the exact history of the yeast — such as determining the order and likely timing of different events in its evolution — was beyond the team’s grasp, however. While the yeasts’ polyploid genome gave them a way to peer into its family tree, it’s by no means stable; it changes each time yeast cells divide. On the one hand, this makes is impossible for the team to reconstruct its evolution; on the other hand, the same process likely played an important part in the domestication of yeast and its subsequent specialization to various brewing styles.

That’s a good trade-off in my book.

The paper “A polyploid admixed origin of beer yeasts derived from European and Asian wine populations” has been published in the journal PLOS Biology.

“Wearable microbrewery” could serve as radiation exposure marker

Just like yeast yields bread and beer, it could help lab workers track their daily radiation exposure quickly and effectively.

Workers in hospitals and nuclear facilities can wear disposable yeast badges to check their daily radiation exposure instantly. (Purdue University image/Kayla Wiles).

As I was preparing a homebrewed beer batch a few days ago, I couldn’t help but wonder at the marvel that is yeast. This tiny organism, so small and unassuming, makes so much of what we take for granted happen. Mankind has been using yeast for its selfish purposes for thousands of years, and yet we may only be tapping into a very small portion of what it can actually offer.

For instance, Purdue University researchers think it can be of great help when monitoring radiation exposure. They’ve designed a simple disposable badge which, in addition to yeast, only contains paper, aluminum, and tape. You’d take it, go about your work, and then simply activate the yeast with a drop of water. This will show radiation exposure as read by an electronic device. It’s simple, it’s elegant, and it’s pretty effective.

“You would use the badge when you’re in the lab and recycle it after you’ve checked your exposure by plugging it into a device,” said Manuel Ochoa, a postdoctoral researcher in Purdue’s School of Electrical and Computer Engineering.

The problem is, radiology workers are routinely exposed to low doses of radiation. If you go and you have an X-Ray once in a while, you wouldn’t worry about it at all — but if that’s your job, things start to change. While good design and protective gear largely keep workers within a safe range of radiation exposure, absorbing a little bit is almost unavoidable.

So these workers wear badges which help monitor their overall exposure. But the process is slow and cumbersome, researchers explain.

“Currently, radiology workers are required to wear badges, called dosimeters, on various parts of their bodies for monitoring their radiation exposure,” said Babak Ziaie, Purdue professor of electrical and computer engineering. “They wear the badges for a month or two, and then they send them to the company that made them. But it takes weeks for the company to read the data and send a report back to the hospital. Ours give an instant reading at much lower cost.”

This is where our faithful yeast enters the stage. Much like humans, yeast is vulnerable to radiation. So if you have a yeast badge, the more you are exposed to radiation, the more yeast cells it will kill off. The phenomenon which makes this process into a quantifiable reading is actually quite neat: when you add water to the yeast, it starts a localized fermentation process — just like with bread or beer. This forms carbon bubbles at the surface, as well as some chemical ions. These ions increase the electrical conductivity of the badge, and this conductivity can be measured — giving an instant value of radiation exposure.

“We use the change in electrical properties of the yeast to tell us how much radiation damage it incurred. A slow decrease in electrical conductivity over time indicates more damage,” said Rahim Rahimi, Purdue postdoctoral researcher in electrical and computer engineering.

Rahimi and colleagues say that if the device goes commercial, the reading process is simple enough that it could be done with a tablet or smartphone.

They also mention that, genetically, yeast is surprisingly similar to human tissue — so by studying the effect that radiation has on yeast, we could ultimately better understand how it affects human cells.

“For yeast, it seems that radiation primarily affects the cell walls of the membrane and mitochondria,” Ochoa said. “Since biologists are already familiar with yeast, then we’re more likely to understand what’s causing the biological effects of radiation in organic matter.”

Chang Keun Yoon, Manuel Ochoa, Albert Kim, Rahim Rahimi, Jiawei Zhou, Babak Ziaie. Yeast Metabolic Response as an Indicator of Radiation Damage in Biological Tissue. Advanced Biosystems, 2018; 1800126 DOI: 10.1002/adbi.201800126


Novel approach to identifying flavor molecules poised to make fermented goods even more delicious

The Germans are coming for your cheese! They want to make it tastier!


Image credits Corinna Barbara.

Researchers from the Technical University of Munich (TUM), the Leibniz-Institute for Food Systems Biology, and the University of Hohenheim have developed a new technique for identifying flavor-bearing protein fragments in fermented foods such as cheese or yogurt. They hope that their findings will form a launchpad from which to upgrade the tastiness of a wide range of foodstuffs.

Cheesy business

Just like everything else, fermented foods draw a lot of their taste from volatile aromatic compounds. Unlike most other things, however, the flavor profile of items like cheese, yogurt, beer, or soy sauce also depends heavily on non-volatile substances (i.e. things you can’t smell). Some of the most important compounds that fall under this category are fragments of (originally-long) proteins broken down by bacteria during fermentation of milk or grains.

Still, there’s a lot of these fragments out there — over 1000 have been documented to impart flavor in fermented-milk products alone. Even worse, they take a whole lot of time and effort to discover. To work around the issue, a team led by Thomas Hofmann, head of the Chair of Food Chemistry and Molecular Sensory Science at TUM, has developed a new method to discover these tasty bits.

The team combined existing methods of proteome (protein) research with methods of sensory research to quickly and efficiently identify the most flavorful protein fragments in a given sample. The team tested their procedure on two varieties of cream cheese — which had different degrees of bitterness. The goal was to identify exactly which protein fragments gave the cheeses their bitter off-taste.

“We coined the term ‘sensoproteomics’ for this type of procedure,” said Andreas Dunkel from the Leibniz-Institute for Food Systems Biology, lead researcher for the study.

An initial review of the literature on the subject told the team that there would be roughly 1,600 different protein fragments that could create a bitter off-taste in dairy products. Chromatography-coupled mass spectrometer analysis in tandem with computer simulations narrowed the search down to 340 potential candidates. Comparative spectrometric, sensory, and quantitative analyses further reduced the number of fragments responsible for the bitter cheese flavor to 17.

“The sensoproteomics approach we have developed will, in the future, contribute to the rapid and efficient identification of flavor-giving protein fragments in a wide range of foods using high-throughput methods—a significant help in optimizing the taste of products,” says Prof. Hofmann.

The paper “A New Approach for the Identification of Taste-Active Peptides in Fermented Foods” has been published in the Journal of Agricultural and Food Chemistry.

Fresh Yeast.

Wild yeast likely evolved in China, reveals genetic sequencing of over 1,000 strains

French researchers report that yeast, too, should be labeled as ‘made in China’.

Fresh Yeast.

An opened package of compressed yeast, produced and bought in Finland.
Image credits Hellahulla / Wikimedia.

It may not seem like it, but the humble yeast is one of the oldest, most hard-working members of team Human Civilization. I’m not going to go into specifics right now, partly because I’m lazy and partly because Elena already did a wonderful job at covering them, here. Suffice to say that society, as we know it, likely couldn’t have existed without the fermenting fervor of yeast.

Despite this, yeast is pretty poorly understood. For example, we know everyone uses it, but not where it first came from. A team of two French geneticists — Gianni Liti from the Université Côte d’Azur, and Joseph Schacherer from the Université de Strasbourg — set out to better understand it.

The team was nothing if not thorough. Their work involved sequencing over 1,000 yeast genomes, ranging from the usual sources such as baker’s or brewer’s yeast to those found in sewage, oil-contaminated asphalt, termite mounds, sea water, one infected nail from a 4-year-old Australian girl. Their approach was thorough by design — the scientists wanted to re-create yeast’s origin and evolutionary path. Getting their hand on as many wild, little-known strains of yeast from as many backgrounds as possible would help paint an accurate picture.

Spoiler alert: it comes from Yeast Asia

“It’s easy to get a thousand wine strains,” says Schacherer, “But that’s not how we wanted to proceed.”

Their results point to East Asia (China) as the yeast’s area of origin.

The most telling clue, according to the team, is that yeast recovered in and around China has the most genetic diversity anywhere in the world. The massive sequencing effort revealed that there are more genetic differences between yeast strains in Taiwan and Hainan — two close-by tropical islands off the coast of China — than there are between strains in Europe and the United States, separated by the entire Atlantic.

The team’s hypothesis isn’t much different than the path what we think humanity followed: the out-of-Africa hypothesis. Just as all of us today descend from populations that came out of Africa, all yeast everywhere descends from strains in East Asia. After these wild yeast strains made it out of Asia, humans likely domesticated them several times for use in food preparation and brewing.

Another surprising find was how strains differed from each other. The standard measure of genetic difference is to look at the same gene in two separate strains and compare the two — how much each gene’s ‘letters’ change, is an indication of how long ago the strains diverged. However, the team found that another metric, the number of times a particular gene is repeated in the genome (known as ‘copy-number variation’) accounts for most of the differences between strains.

This may hold true for other species as well, possibly even us, but we just don’t know for sure; yeast is more easily studied, as its genome is some 200 times shorter than our own. The results, the team says, should prompt more research into copy-number variation in humans, as well.

The paper “Genome evolution across 1,011 Saccharomyces cerevisiae isolates” has been published in the journal Nature.


Pee, Poop, and Perspiration Will Be Useful in Traveling to Mars

People have effectively been able to acquire fuel and, consequently, energy from human urine. This capability has been known for a number of years. In late 2012, a small group of teenage girls from Nigeria made the news by presenting a generator that ran on urine at the Maker Faire Africa. In their generator, the pee is poured into an electrolytic cell where the hydrogen is isolated from other components in the liquid.

The hydrogen is then purified by passing through a filter. From there, it’s sent to a gas cylinder from which it is further pumped into a cylinder containing liquid borax. The borax aids in separating the hydrogen gas from any remaining moisture. The final step is for this gas to be sent to the generator. The girls’ machine was able to supply six hours’ worth of electricity by using a mere liter of liquid waste.

Of course, this was a rather simple apparatus primarily for display, but the important thing is it worked! Urine’s use for producing gas and/or syngas (synthesis gas) has the potential to be quite revolutionary.

Waste as a Water Source in Space


Credit: Wikimedia Commons.

Recycling everything possible in extraterrestrial day-to-day life and travel saves both space and money. For a while now, astronauts on the International Space Station have been recycling their own perspiration and pee. The purified output is clean water, which is drunk a second time over. This cycle can be repeated over and over.

You’ve heard of twice-baked potatoes? Well, twice-expelled waste is starting to catch up in its popularity. Human urine and condensate (including breath moisture, human sweat, shower runoff, and animal pee) are all distilled and reverted to clean drinking water. As of 2015, about 6,000 extra liters of water are recycled each year.

Waste Empowering Yeast

One of the molecules which makes up our urine is called urea. Furthermore, urea is composed of nitrogen and carbon. Both of these chemicals are needed to feed a yeast, Yarrowia lipolytica, which when genetically tweaked properly can take a variety of forms such as bioplastics and even fatty acids. One particular fatty acid necessary for human health and functionality is Omega-3. The brain requires this nutrient.

Thus, Yarrowia lipolytica is being tested to hopefully be able to produce Omega-3’s efficiently in the future. This would be a great aid to humanity in the occasion of a manned mission to Mars or elsewhere. In addition, future astronauts will use 3D printers onboard their spacecraft to generate tools and other needed objects made of plastic. Yet again, the yeast can be altered to produce a certain type of polyester which could be employed for this purpose.

Feces and Urine for Future Food

The sheer quantity of food needed to sustain a manned mission to Mars remains a big problem. However, a clever party of researchers from Pennsylvania State University believes to have found an efficiently ingenious answer. The concept was discussed in a paper published in late 2017. Their space-saving device, a bioreactor, uses the urine as well as the feces of astronauts to feed a non-harmful bacteria that, in turn, is capable of sustaining the human space travelers.

Within the bioreactor, the solid and liquid waste become condensed leaving salts and methane gas in its place. It’s the methane which is used to grow the microbial mush, an edible element with a texture similar to that of Vegemite, a thick Australian spread made up of leftover brewers’ yeast extract along with an assortment of additives.

As you have seen, our astronauts’ waste will not be wasted. Scientists will surely engineer more ways for bodily waste to be put to beneficial use.

Wash hands sign.

Waste not, want not: astronauts to turn pee into nutrients, tools on deep-space missions

Astronauts heading out to Mars or other corners of deep space will need systems capable of producing critical nutrients and materials on-route while keeping their craft’s weight as low as possible. One team of researchers is looking to down two birds with one stone by using yeast to turn astronaut’s urine and carbon dioxide into plastic mass and omega-3 fatty acid.

Wash hands sign.

Image credits Amanda Mills.

You can’t stuff a spaceship with everything astronauts will possibly need for a journey because every bit of extra weight translates to a large increase in the fuel required to get to space. Which begs the question: what happens if a crew member loses a bit of kit or a tool while working outside of the spaceship? How will they get a replacement? Well, one way to do it is to have some sort of production system on-hand to be used in such cases — and we have 3-D printing that. 

As for the raw materials, scientists are increasingly turning to the astronauts themselves, who will generate constant material, in the form of waste, by simply eating or breathing. And the researchers are letting nothing go to waste.

Liquid assets

“If astronauts are going to make journeys that span several years, we’ll need to find a way to reuse and recycle everything they bring with them,” says Clemson Univeristy Ph.D Mark A. Blenner, lead author of a study looking to turn waste CO2 and urine into a usable resource.

“Atom economy will become really important.”

Here on Earth, we can play fast and loose with matter, since we’ve got plenty lying around. But in space, every molecule of usable material comes at a premium and we simply can’t afford to discard it. Towards that end, he and his team are working on turning astronaut-waste into things the crew actually need, such as plastic mass for 3D printing and vital nutrients.

These last ones in particular are tricky. Some vital nutrients, such as omega-3 fatty acids, can’t be stored for more than a few years before they degrade. Since any meaningful expedition will take more than that limited shelf life, we’ll need to produce such nutrients on-route a few years after launch and after the ship reaches its destination.

The team developed a biological system that relies on several strains of the yeast Yarrowia lipolytica which can be loaded in a dormant state and awakened when the crew needs to start producing material or nutrients. Y. lipolytica need nitrogen and carbon to grow, both of which are luckily in supply from the astronauts themselves. Blenne’s team showed that the yeast can feed on nitrogen contained in urine without any extra processing. For CO2, it’s a bit more complicated. It’s abundant in astronauts’ exhaled breath (or the atmosphere on Mars) and needs to be scrubbed out of the air anyhow or it becomes toxic, but the yeast can’t use it as-is in its gaseous form. To address that issue, the team is relying on photosynthetic algae known as cyanobacteria to fix the carbon dioxide into a form Y. lipolytica can absorb.

Solid gains

One of the strains of Y. lipolytica will churn out omega-3 fatty acids for the crew, which plays a key role in maintaining the brain, heart, and eyes in good health. Another strain of the yeast was engineered to biosynthesize monomers and link them together to form polymers — plastic mass. These polymers can then be run through a 3D printer so the crew can create spare parts, tools, or any other object they need on the journey.

Currently, both strains only produce a small quantity of both polymer or omega-3, but the team is working on increasing yields. They’re also trying to make new strains that can produce other types of monomers with different physical properties, so future crews have access to a wider range of materials to better address any need.

But the work Blenner’s team is performing isn’t only for outer space — the omega-3 strain is just as useful for nutrition down here, and will be a particular boon to the aquaculture industry. Seafood raised in fish farms need omega-3 supplements, which in a particular twist of irony we’re currently producing from wild seafood and then feeding it to our fishy crops. Blenner’s yeast could solve that issue and finally allow ocean ecosystems some respite from fishing.

Overall, the research is also furthering our knowledge of yeast behavior in general and Y. lipolytica in particular. Although it is a yeast, it’s not very well studied and differs quite a bit from more mainstream strains of yeast, such as those used in alcoholic fermentation.

“We’re learning that Y. lipolytica is quite a bit different than other yeast in their genetics and biochemical nature,” Blenner says. “Every new organism has some amount of quirkiness that you have to focus on and understand better.”

The team presented their paper “Biosynthesis of materials and nutraceuticals from astronaut waste: Towards closing the loop” at the 254th National Meeting & Exposition of the American Chemical Society (ACS) in Washington, which will last through Thursday.

Researchers complete 30% of the synthetic yeast chromosome — synthetic life is just around the corner

An international research effort to construct the first fully synthetic yeast is well under way. The scientists have fully designed the fungus’ genome and have already built five of its final sixteen chromosomes — planning to have the rest completed by the end of the year.

Image credits Paul / Pixabay.

Yeast has to be humanity’s favorite fungus. Sure, other shrooms taste better in a saute or make for a much more entertaining way to spend some free time, but yeast has been by our side since times immemorial. Whenever we’ve needed something fermented, yeast had our back. Without it, there would be no alcohol, no bread, no fish sauce!

Since modern industries need to ferment more stuff much faster and into a more varied range of end products than ever before (think biofuels, insulin, antibiotics, THC), scientists have spent the last two decades sequencing yeast genome to produce different strains useful for all these products. That still leaves us limited by much of the yeast’s genome, however, which nature sadly didn’t design for industrial applications — but not for long.

Led by NYU Langone geneticist Jef Boeke, PhD, and a team of more than 200 authors, the Synthetic Yeast Project (Sc2.0) has designed a full genome for a functioning synthetic version of Baker’s yeast (S. cerevisiae). The latest issue of seven papers coming from the group shows that they’ve successfully constructed almost one third of this genome — 5 out of 16 chromosomes. They plan to have the rest ready by the end of the year. The new round of papers consists of an overview paper and five individual ones describing the first assembly of synthetic yeast chromosomes synII, synV, synVI, synX, and synXII. A seventh paper provides a first look at the 3D structures of synthetic chromosomes in the cell nucleus.

“This work sets the stage for completion of designer, synthetic genomes to address unmet needs in medicine and industry,” says Boeke, director of NYU Langone’s Institute for Systems Genetics.

“Beyond any one application, the papers confirm that newly created systems and software can answer basic questions about the nature of genetic machinery by reprogramming chromosomes in living cells.”

Learning the A’s and C’s

Apart from the immediate utility of having a tailorable yeast strain to apply in industry, Baker’s yeast was selected because of it’s relative simplicity and similarity to human cells. Sc2.0’s researchers are akin to a group of genetic programmers — they add or remove parts of DNA from chromosomes to dictate new function or prevent diseases or weakness to various factors. It makes sense to start with a simple ‘program’ until you learn the basics, which you can then apply to more complex systems.

Three years ago, Sc2.0 successfully assembled the first synthetic chromosome (chromosome 3 or synIII) out of 272,871 base pairs — the blocks which make up DNA. This process starts with the researchers screening libraries of yeast strains to find which genes are most likely to have useful features. Then, they planning thousands of permutations in the genome in a process somewhat similar to very rapid evolution. Some of these changes introduce the new genes to make the yeast exhibit desired features, others remove bits of DNA which were shown not to have a function in past trials.

Stained polytene chromosomes.
Image credits Doc. RNDr. Josef Reischig, CSc.

After the computer models are finished, the team starts assembling the edited DNA sequence bit by bit until they have the whole thing. The completed sequences are then introduced into yeast cells, which handle synthesizing and finish building the chromosomes — the latest round of papers describes a major innovation in this last step.

Until now, the researchers had to finish building once piece of a chromosome before work could begin on the latter, severely limiting their speed. These sequential requirements bottle-necked the process and increased cost, Boeke said. So the team made efforts to “parallelize” chromosome assembly, with different labs around the world synthesizing different bits in strains which were then mated. The resulting yeast strains would in some instances have even more than one fully synthetic chromosome. A paper led by Leslie Mitchell, PhD, a post-doctoral fellow from Boeke’s lab at NYU Langone, described the construction of a strain containing three synthetic chromosomes.

“Steps can be accomplished at the same time in many locales and then assembled at the end, like networking laptops to create a global super computer,” says Mitchell.

Another paper describes how a team at Tsinghua University used the same parallelized method to synthesize chromosome synXII, which formed a molecule with more than a million base pairs (one megabase) in length when fully assembled — the longest synthetic chromosome ever made by humans. It’s still only 1/3,000 the length of a human chromosome, but it’s closer than we’ve ever come before.

The researchers also found that they can edit some dramatic changes into the yeast genome without killing the cells. They survived even when the team moved whole sections of DNA from one chromosome to another, DNA swaps between yeast species, often with very little effects on the cells.

There’s a huge potential to synthetic yeast. Scientists could tailor their genome to produce anything we need from drugs, to food, new materials, almost anything — just from sugar and raw materials. It could fundamentally change how we think about a lot of industries, potentially churning the same products as factories and labs from a humble barrel.

But the work performed under the Sc2.0 project also revolutionizes how we know about genome building and synthetic life. Yeast is simple, but the end goal is to one day move on to tailor-made plants, maybe even to perfect the human genome. But we’re still a long way from that. Right now, the team will focus on getting their yeast’s final A’s, T’s, G’s, and C’s in place.


Lichens actually comprise a threesome, not a partnership

When the nature of lichens was discovered 140 years ago, they became the most prominent example of symbiosis, a term that defines a mutually beneficial relationship between two dissimilar organisms.

Image credit Pixabay

Image credit Pixabay

In the case of lichen, the filaments of a single fungus create protection for photosynthetic algae or cyanobacteria, which provide food for the fungus in return. However, a new study reveals that there is actually a third organism involved in this relationship – a yeast that likely provides the structure for “leafy” or “branching lichens.”

“These yeast are sort of hidden just below the surface,” said John McCutcheon, a genome biologist at the University of Montana, and senior author of the study. “People had probably seen these cells before and thought they were seeing something else. But the molecular techniques we used happened to be especially good for spotting the signal of a separate organism, and after years of looking at the data it finally occurred to us what we were seeing.”

McCutcheon’s team made the discovery after studying two lichen species obtained from Missoula, Montana mountains – Bryoria fremontii and B. tortuosa. Despite B. tortuosa possessing a yellow color due to the presence of vulpinic acid, genetic tests revealed identical fungus and alga in both species. However, they also discovered the genetic signature of a third species – a basidiomycete yeast – in both species, although it was more abundant in B. tortuosa.

Additional testing of 56 different lichens from around the world revealed that each one has its own variety of basidiomycete yeast, suggesting that lichens actually comprise a threesome, not a couple, essentially rewriting 150 years of biology.

The team believes that this newly discovered yeast could play a role in creating the large structures seen in macrolichens, which would explain why these particular lichens are hard to grow in the lab when using just a fungus and alga.

“This doesn’t prove that they’re necessary to create the structure of the macrolichens, or that they do anything else for that matter,” McCutcheon said. “But its early days. It took a lot of work just to discover that they were there. We’re interested if the yeast is making these important compounds, or possibly enabling the other fungus to make them. We don’t know, but it’s the obvious next question.”

Journal Reference: Basidiomycete yeasts in the cortex of ascomycete macrolichens. 21 July 2016. 10.1126/science.aaf8287

Scientists engineer yeast that creates active marijuana compound, THC

Scientists have genetically modified yeast to produce the main psychoactive substance in marijuana, THC. Responsible for most of weed’s effects (including the high), THC can also be used for medical purposes, to treat symptoms of HIV infection and chemotherapy.

Image: Brett Levin/Flickr

Tetrahydrocannabinol (THC), or to be more precise, its main isomer (−)-trans-Δ9-tetrahydrocannabinol is the principal psychoactive constituent of cannabis. In April 2014 the American Academy of Neurology published a systematic review of the efficacy and safety of medical marijuana and marijuana-derived products in certain neurological disorders, identifying 34 studies that meet the necessary criteria and that document its potential medical uses.

“This is something that could literally change the lives of millions of people,” Kevin Chen from Hyasynth Bio, a US-based company that’s been engineering yeasts to produce both THC and cannabidiol – another active compound that has shown promise as a medical treatment – said in a statement.

Researchers from the Technical University of Dortmund in Germany published their results in the journal Biotechnology LettersThey looked into which genes of the marijuana plant produce THC, and then engineered those genes into yeast, which now creates THC itself.

The goal here isn’t just to create THC – because you know, marijuana is doing a pretty good job at that – but to find a better way to create THC in countries where the growth of marijuana is illegal even for research purposes. Synthetic versions of the substance are currently available, but the goal of the German researchers was to find a more efficient and cheaper way of producing it. Yasmin Hurd, a professor of neuroscience and psychiatry at Icahn School of Medicine at Mount Sinai, told Tech Insider that using all the compounds in marijuana simultaneously is like “throwing 400 tablets in a cocktail and saying ‘take this,'” rather than figuring out which component of that cocktail is really beneficial for the specific disease. We need to somehow figure out what compounds have medical potential. Hopefully, this yeast will help.

Despite the recent surge in the news about cannabis’ medical properties, there is a limited evidence that it is actually effective against the conditions it is currently prescribed for. Researchers are currently trying to delimitate its actual benefits from wishful thinking.

Journal Reference: Bastian Zirpel, Felix Stehle , Oliver Kayser – Production of Δ9-tetrahydrocannabinolic acid from cannabigerolic acid by whole cells of Pichia (Komagataella) pastoris expressing Δ9-tetrahydrocannabinolic acid synthase from Cannabis sativa l. Biotechnology Letters

Scientists describe method to create morphine at home

Scientists have managed how to create morphine using a kit like the ones used to make beer at home. They used genetically modified yeast to perform the complicated process of turning sugar into morphine, and while they believe this can have huge medical significance, they also express concerns about “homebrewed” drugs.

“I’ll have a morphine ale, please”. Image via Serious Eats.

If you brew beer at home, then you know that the key to the process is the microscopic yeast that turns the sugars into alcohol. But by using an extract from poppies and a modified version of yeast, you can create even more than that – opiates such as morphine.

The first reaction the researchers had was the one you’d expect – they warned that it will only take a few years drugs obtained through such techniques hit the streets.

“We’re likely looking at a timeline of a couple of years, not a decade or more, when sugar-fed yeast could reliably produce a controlled substance (such as morphine),” lead researcher and bioengineer John Dueber, from the University of California, Berkeley said in an interview.

He also said that it’s important for scientists to first develop this process, in order to stay ahead of drug organizations and tell authorities what they might be dealing with.

“We need to be out in front so that we can mitigate potential abuse.”

Dueber and his team first thought of this process when they discovered that a certain type of enzyme can turn glucose sugars into morphine. This was not necessarily a novel idea, but scientists have previously struggled to make a viable product, because each of these enzymes pushed the reaction too far and destroyed desired compounds before they could be extracted. Especially one stage of the process, obtaining an intermediary chemical called reticuline – had been a stumbling block. It was no easy task, but the Berkeley team realized that they could have a yeast do the work for them. Dueber said:

“What you really want to do from a fermentation perspective is to be able to feed the yeast glucose, which is a cheap sugar source, and have the yeast do all the chemical steps required downstream to make your target therapeutic drug. With our study, all the steps have been described, and it’s now a matter of linking them together and scaling up the process. It’s not a trivial challenge, but it’s doable.”

Basically, anyone with brewing experience could have a go at the process – and that’s both good and bad. There is a high demand for morphine, a substance used to treat both acute and chronic severe pain. Developing a simple and cheap method to create it would be certainly be welcome, but there’s another side to this. Morphine is also the main psychoactive chemical in opium and it has a high potential for addiction – having such a substance available for any homebrewer can be extremely dangerous, and this technology in the wrong hands is just asking for trouble. The prospect of brewing strong drugs using yeast is not a pleasant one, and raises questions about regulating genetically modified yeasts.

Prof Paul Freemont, one of the directors of the Centre for Synthetic Biology and Innovation at Imperial College London, said:

“Making opioids that can be used in an illegal sense makes this an important story. It’s technically demanding to make these strains, but in the future who is to know? That is why this is such an important time – how do we regulate these strains?”

We don’t want to open another battle in the already losing war on drugs, but we do want cheap morphine, and it seems inevitable that yeast-brewed drugs will hit the streets in a few years, with no plan to manage them in sight. It’s a complicated question, but the take-away message should be pretty clear – using science, you can make amazing things with little resources, but seriously, don’t try this at home.

Journal Reference: William de Loache et al. An enzyme coupled biosensor enables (S)-reticuline production in yeast from glucose. Link

Of Yeast and Flies: The Science of why Beer is so Delicious

Whether you enjoy a strong malty taste, or a fruity savor, or even just a subtle aroma in your beer – you have yeast to thank for. Yeast imbues beer with aromatic molecules that account for most, if not all of the final flavor. But why is it that they create all this wide array of flavors? Kevin Verstrepen, a yeast geneticist at the Flanders Institute for Biotechnology and the Belgian University of Leuven has found the answer – and he has done so because he was in a hurry to get to the bar.

Delicious Beer

Delicious beers – image via Cottage Life.

We’ve written about Verstrepen before – he is part of an initiative to map the Beer Yeast Genome Project – an attempt to map the yeast’s genome in an attempt to make more diversified and better beers.

“With this information, we’ll be able to select different properties in yeasts and breed them together to generate new ones,” Dr. Verstrepen said in June. “In a few years we might be drinking beers that are far different and more interesting than those that currently exist.”

Now, in a new paper publishes in the journal Cell, he detail the results of four experiments on yeast. As it turns out, for yeast, it’s all a matter of attraction – they develop the aromas to lure in wandering flies, to which yeasts hitch a ride so they can disperse throughout nature. This theory originated (how else?) as a result of a desire to drink.

“This theory actually came about entirely by accident,” Verstrepen says. Fifteen years ago, working on his Ph.D., he was investigating the gene that controls the production of these aromatic molecules in yeast. “At one point on a Friday night, I was in hurry to get to the bar and didn’t clean up my experiment as well as I should have,” he says.

He accidentally left out three flasks of yeast.

“One flask had a mutant strain of yeast that produced 100 times more [of these aromatic molecules], one flask contained normal yeast, and a third had a yeast with this aroma gene partially knocked out,” Verstrepen says. “When I returned Monday morning, I found that somehow fruit flies had gotten into the lab,” he says. And realizing that he had unwittingly set up an experiment, he wrote down the results. “Fifty flies drowned in the mutant flask, two drowned in the flask of normal yeast, and the flask with the [nonaromatic] yeast didn’t have any,” he says. “You don’t have to be a genius to start to draw some conclusions from that.”

Of Yeast and Flies

Beer yeast – it may be gross, but it makes beer delicious, so we’ll just chalk it up to good guys. Image via TalkingAlcohol.

Indeed, even without any experience in the field, common sense suggests that more aromatic yeasts attract more fliest. But that impromptu experiment, although written down, was abandoned for 15 years. Now, researchers finally remade it, in a controlled environment. They took a potent strain with a strong aroma and eliminated the gene responsible for creating the aroma. When they compared how attracted flies are to the two versions of the yeast, flies overwhelmingly preferred the fruity, aromatic yeast.

In order to check if it was indeed the aromatic particles and not some other, unidentified element, they added the aromatic molecules back into the scentless yeast tray—so that the aromas of both trays would be identical. Indeed, when the fruit flies entered the arena, they showed no preference.

To further test the theory, they created another setting – they wanted to look at the flies’ brains as they smell the yeast.

“It’s actually a really cool setup,” Verstrepen says. The researchers used flies with proteins in their brains that phosphoresce (think, glow in the dark) with neural activity. “So you can slide open the skull of the flies [and] monitor their brain activity by literally watching their brains flash up phosphorescently,” Verstrepen says. Using this technique, the researchers discovered that one chemical—isoamyl acetate—made the flies’ brains go wild. This should come as no surprise – this is the substance which appears when fruits turn overriped.

Making Beer from Crushed Flies

Clearly this made for an interesting paper. But what was even more interesting wasn’t even included in the paper. Out of sheer curiosity, Verstrepen gave his colleagues fly traps and asked them to collect flies from their homes and neighborhoods. When they returned, he searched the flies for yeasts. Sure enough, he found some. He cultured these yeasts and found them to be pleasantly aromatic. After this, he did what every other sane human being would have done.

“We made beer with them,” Verstrepen says.

Apparently, the beer was delicious. I don’t know about you, but I’d taste some of that!

Journal Reference: Joaquin F. Christiaens, Luis M. Franco, Tanne L. Cools, Luc De Meester, Jan Michiels, Tom Wenseleers, Bassem A. Hassan, Emre Yaksi, Kevin J. Verstrepen. The Fungal Aroma Gene ATF1 Promotes Dispersal of Yeast Cells through Insect Vectors. DOI: http://dx.doi.org/10.1016/j.celrep.2014.09.009

The Family Tree of Beer: A Team of Geneticists is creating the Beer Yeast Genome Project

In a lab in San Diego, Troels Prahl, a brewer and microbiologist at the Southern California yeast distributor White Labs sits at the tasting bar in front of 4 open half pints of beer. Each of them is different, in color and flavor, ranging from a crisp body of raspberry, rosemary and banana to a dry and subtle blend of nutmeg and fresh straw. But with the single exception of the yeast they were brewed from, all the beers are identical.

Tw0 organizations, White Labs and a Belgian genetics laboratory have teamed up to create the first genetic family tree for brewing yeasts and the beers they make, by analyzing more than 2,000 batches of beer. So far, they’ve sequenced the DNA of more than 240 strains of brewing yeasts from around the world. Alongside samples from breweries like Sierra Nevada, Duvel Moortgat and Stone, “we’ve thrown in a few wine, bakers, bio-ethanol and sake yeasts to compare,” said Kevin Verstrepen, director of the lab in Belgium.

“Yeasts can make over 500 flavor and aroma compounds,” said Chris White, the founder of White Labs, affecting not only a beer’s alcohol level, but also its taste, clarity and texture.

But while this study will provide valuable scientific information, showing which yeasts are related to which and how they evolved, it also has an economic significance, allowing researchers to create new types of beer.

“With this information, we’ll be able to select different properties in yeasts and breed them together to generate new ones,” Dr. Verstrepen said. “In a few years we might be drinking beers that are far different and more interesting than those that currently exist.”

For brewers today, yeast options are very limited. Nowadays, most yeasts are highly specialized, so mixing them together to make new drinks is almost never usable (it’s like mixing a family and a sports car to get something in between – doesn’t really work). Even genetic attempts to mix them rarely yield successes.

Also, while the technology of developing new yeasts by splicing new genes in a lab exists, consumers are highly reluctant when it comes to consuming genetically modified products. In other words, GMOs are not attractive – even beer’s GMOs.

“Right now we have a few hundred genetically modified yeast strains patiently waiting in our laboratory’s freezer,” said Jan Steensels, a microbiologist with the Belgian lab, “but most brewers and consumers don’t want anything to do with them.”

This is where this Yeast Genetic Tree steps it – the knowledge from this genome could enable researchers and companies to brew new beers without resorting to genetic modification. If you want to obtain a specific mix of tastes, flavors and alcohol content, you first have to know where to look in the genetic tree. Then, by knowing exactly which genes to track, using specialized software and computers, they will be able to mix different yeasts until they obtain the exactly properties they want.

“So let’s say there’s a yeast that produces an amazing fruity aroma in beer, but can’t ferment past 3 percent alcohol,” said Chris E. Baugh, a microbiologist at Sierra Nevada Brewing Company in Chico, Calif., who is not involved in the project. A scientist who understood the genetics, he continued, “could then breed it with a more alcohol-tolerant strain.”

Still, this will almost certainly not phase brewing giants, which for decades have clinged to their recipes, but it may lead to a boom of smaller, specialized, and more tasty beers.

“Where this is really going to take off is in the craft brewing scene,” Dr. Baugh said. The number of craft breweries and microbreweries has exploded in recent decades, to roughly 2,500 today from fewer than a dozen in 1980 (in the US).

Interestingly enough, the cost of sequencing yeast genome is not that high. As a matter of fact, the technology is so inexpensive that the first 96 strains at White Labs were sequenced free of charge by the biotechnology company Illumina, to assess one of its new sequencing machines. The real challenge lies in the immense work volume required to finish the project.

 “This project strikes me as sort of an inevitable thing that one can do,” said Randy W. Schekman, a yeast geneticist at the University of California, Berkeley, who shared the 2013 Nobel Prize in Physiology or Medicine. With the falling costs and rising speed, he added, “the sequencing is almost trivial at this point.”

This, he believes, is an important step for an industry that has long been way of genetic modifications:

“Until recently, the brewing industry has been remarkably resistant to using the techniques of genetics and molecular biology to improve their brewing strains,” Dr. Schekman said. “It’s long overdue that someone has actually delved into the molecular basis between the differences in brewing strains.”

Via NY Times.



Yeast chromosome engineered from scratch: creating cretures in a lab

In a huge breakthrough in synthetic biology, scientists at Johns Hopkins University have engineered from scratch a yeast chromosome. This is the first time scientists have been able to assemble a chromosome from a creature as complicated as a yeast, namely a prokaryrite. The implications of this research are far and wide. For one, the developments at Johns Hopkins provide an invaluable learning tool and launching platform for future research in synthetic biology. More immediate applications include the biofuel industry and of course beer.

Humans have been growing yeast for practical purposes ever since they figured out how to brew beer and bake bread thousands of years ago. Through selective breeding and close manipulation, mankind has been essentially engineering yeast for a long time. This time, however, the researchers led by Jef Boeke have gone the extra mile and genetically engineering an entire organism (the yeast) from scratch.

Yeast 2.0

Their work involved designing and writting a code made up of roughly 11 million letters of DNA—the As, Cs, Gs, and Ts that write the book of life. This code was synthesized and subbed in for a yeast’s natural DNA, thus obtaining a brewer’s yeast’s DNA with a completely altered  chromosome. Chromosomes are organized structures of DNA and proteins that are found in cells. A chromosome is a singular piece of DNA, which contains many genes, regulatory elements and other nucleotide sequences. Chromosomes vary extensively between different organisms. The DNA molecule may be circular or linear, and can contain anything from tens of kilobase pairs to hundreds of megabase pairs. Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller circular chromosomes, although there are many exceptions to this rule.

For instance, each human cell contains 23 chromosome pairs, for a total of 46. The man-made yeast chromosome represents about three percent of all of the DNA that makes a yeast.

“Yeasts have 16 chromosomes, and we’ve just completed chromosome 3,” Boeke says. “Now it’s just a matter of money and time.”

In 2010, the J. Craig Venter Institute reported a landmark advancement in synthetic biology, after scientists there built all of the DNA for a bacteria from scratch. Yeasts are one level up bacteria, however. While they’re both single-celled organisms, yeasts are eukaryotic, in the same group as plants and humans, while bacteria are eukaryotic, similar to the very first living things that formed on Earth billions of years ago.

“The synthesis and design of the first eukaryotic chromosome is obviously an exciting milestone,” says Farren Isaacs, a cell biologist at Yale University who was not involved in Boeke’s team. “Eukaryotic” refers to the grouping of life that yeast belong to.

Genetically modified organisms have come a long way in recent years, but while researchers have concentrated their efforts on designing organisms marginally similar to those born from pure evolution, adding or deleting just a couple of genes here and there, the new yeast is proof of an entirely new organism, engineered from scratch.


So their beer yeast isn’t just some carbon copy of nature, but an entirely new one – an improved version, some may say. A lot of DNA was trimmed down, parts of redundant or unnecessary segments of code called “junk DNA”. The researchers even added some stretches of DNA that give the chromosome a latent superpower that doesn’t come into play unless it’s triggered.  “It’s almost akin to being able to trigger evolution,” Isaacs says.

To test if the synthetic version with the cut out chromosome III can support yeast life, the researchers simply added the chromosome back into the yeast from which the natural version was removed. In the lab, the hybrid grew and reproduced just like its cousins.  “It looks like it, it behaves like it, it smells like it,” Boeke says. “Basically, you wouldn’t know the difference unless you take the next step and introduce what we call the genome scrambling system into it.”

There’s been a lot of talk about junk DNA, however. For instance, it’s been found before that what scientists used to call redundant genetic code turned out to be pretty useful. It’s just that some code becomes active only in particular situations. It could be that if yeast is subjected to particular environmental stimuli, like a specific temperature or pressure, it may not survive or behave differently than its natural brethren. If this happens, then it may be for the better since it would show that the cut-out genes actually do something providing an excellent learning tool.

“So what we’re doing is, in some sense, a risky business,” Boeke says. “There’s not a flag on each segment saying ‘this one’s not important’. It’s really a judgment call at a certain stage.” Luckily, yeasts, like fruit flies and mice, are one of the best-understood organisms in all biology, so the scientists relied on a huge genetic database to guide them. “But if we make a mistake, as we’ve found in some of our unpublished work, the penalty could be a dead yeast,” he says. “So we were pretty conservative.”

The future of beer

Yeast is an important component in brewing and in most beers, it’s responsible for the dominant flavour. Some yeasts make for a good flavour, but they ferment too little alcohol, which can be frustrating for research scientists at breweries. A modified synethic yeast could solve many issues. But would you drink a genetically modified beer? Some brands stay away from GMO hops because they offer their consumers all-natural flavour. So a more likely candidate for synethic yeast may be the biofuel industry where GMO corn ethanol is widely produced.

Findings appeared in the journal Science.


Missing link finally found! Beer’s missing link that is

For men everywhere beer lovers everywhere, yeast is probably the best microorganism there is, because it is used in one of the most popular drinks: beer. But its identity has puzzled researchers for decades now, as they were unable to pinpoint its exact origins. However, they now believed they have solved this puzzle and traced the yeast back to Patagonia, from where it sailed to Europe some 500 years ago.

Having traveled from the New World to Europe, it met with a long lost distant relative – a type of yeast used to make bread and some types of wine. What happened from there is history. In a study published in the Proceedings of the National Academy of Sciences describe how they discovered the origin and travel of this organism after what they claim to be an exhaustive research.

“People have been hunting for this thing for decades,” said Professor Chris Hittinger, from the University of Wisconsin-Madison in the US. “And now we’ve found it. It is clearly the missing species.”

The yeast would have had a variety of means to reach its destination, most likely on a piece of wood or on the belld of a fruit fly. Genetic mutations then occured naturally to create a yeast whih pleases millions and millions of people.

“Our discovery suggests that hybridisation instantaneously formed an imperfect ‘proto-lager’ yeast that was more cold-tolerant than ale yeast and ideal for the cool Bavarian lagering process,” said Prof Hittinger. “After adding some new variation for brewers to exploit, its sugar metabolism probably became more like ale yeast and better at producing beer.”

Well, this is definitely a story to say next time you hit the pub with your friends.