Interactions between yeast and bacteria lead to prion induction and stuck fermentations

Really glad we were finally able to get this paper out. Keep any eye out for a follow up paper about the fermentation performance of [GAR+] cells.

Cross-Kingdom Chemical Communication Drives a Heritable, Mutually Beneficial Prion-Based Transformation of Metabolism

Daniel F. Jarosz11, Jessica C.S. Brown1112, Gordon A. Walker, Manoshi S. Datta, W. Lloyd Ung, Alex K. Lancaster, Assaf Rotem, Amelia Chang13, Gregory A. Newby, David A. Weitz, Linda F. Bisson, Susan Lindquist

In experimental science, organisms are usually studied in isolation, but in the wild, they compete and cooperate in complex communities. We report a system for cross-kingdom communication by which bacteria heritably transform yeast metabolism. An ancient biological circuit blocks yeast from using other carbon sources in the presence of glucose. [GAR+], a protein-based epigenetic element, allows yeast to circumvent this “glucose repression” and use multiple carbon sources in the presence of glucose. Some bacteria secrete a chemical factor that induces [GAR+]. [GAR+] is advantageous to bacteria because yeast cells make less ethanol and is advantageous to yeast because their growth and long-term viability is improved in complex carbon sources. This cross-kingdom communication is broadly conserved, providing a compelling argument for its adaptive value. By heritably transforming growth and survival strategies in response to the selective pressures of life in a biological community, [GAR+] presents a unique example of Lamarckian inheritance.

Ever wonder what the difference is between Ale vs. Lager yeast?

Originally posted on Biochemistry, Molecular, Cellular & Developmental Biology:

Despite being a yeast researcher, and supposedly having a pretty good handle on yeast genetics, I have always struggled to fully understand what the underlying genetic differences are between ale and lager yeasts. Thanks to a great article by Martha Harbison from Popsci, and research done by Libkind et al, I have finally figured it out!

Generally ales are fermented warmer with”top fermenting” yeast, and produce more fruity esters as a result. Lagers tend to be fermented cooler with “bottom fermenting” yeast, and produce more “reductive” or sulfur characters.

Ale vs. Larger

This description, while great for brewers was always unsatisfactory to me as someone with an interest in genetics and taxonomy. This was further complicated by the interchangeable use of S. calsbergensis and S. pastorianus. Top fermenting yeast are generally just plain old Saccharomyces cerevisiae. Bottom fermenting yeasts are generally more variable and have allotetraploid chromosomes, i.e. 4 chromosomes made up of mixed…

View original 671 more words

Bisson Lab in the news for non-GMO sulfurless yeast

Bisson Lab in the news for non-GMO sulfurless yeast

Wine1W

Dr. Bisson using that expert nose

 

A winemaking yeast strain invented by a UC Davis researcher that removes the sulfur odor in wines has been patented and is undergoing development and marketing around the world and locally.

 

The non-genetically modified yeast was developed by Linda Bisson of the UCD department of viticulture and enology and is being marketed in partnership with Vancouver-based Renaissance BioScience Corp.

Local winemakers have heard of the new yeast and could be using the strain to make wine as early as this summer’s harvest, and some larger winemakers already have begun to use the new yeast in blends.

 

The yeast strain, used in fermentation to make wine, was bred through traditional methods to select for a new yeast that produces less hydrogen sulfide, which has an undesirable rotten egg smell, Bisson said. Even at low levels, hydrogen sulfide can mute the desired fruit characteristics of wines.

 

 

Do Yeasts Survive the Winter in the Guts of Wasps?

From Discover Magazine By

 

Yeasts are handy little critters: they help produce the alcohol that make wine and beer so deliciously intoxicating. But how they manage to show up on grapes in vineyards year after year, despite freezing winters when there is little for them to eat, is a bit of a mystery. Scientists thought birds could be keeping the yeasts in their guts through the winter, then sprinkling them (ahem) through vineyards in the spring, but turned out the microorganisms couldn’t survive that long in birds.

Now, scientists have identified a much more promising Florida timeshare of a gut: that of the social wasp. Social wasps feed on vineyard grapes, and their queens do survive the winter, emerging from hibernation to found new colonies in the spring. Italian researchers checked the gut microbes of 61 social wasps collected in Tuscany and other wine regions and found that there were scads of yeasts there, 393 strains to be exact. The wasps carried some yeasts that are similar to those found in the area’s wines, suggesting that they may indeed be a significant year-round reservoir of the microorganisms.

Italian wine owes some of its character to local yeasts, scientists have reported before, and this study lends credence to the idea that it’s not possible to separate conservation of local ecosystems and artisanal food production.

 

While this is certainly an intriguing idea, Saccharomyces cerevisiae can be pretty hardy little buggers on their own without needed to take shelter in the guts of insects. When presented with less than optimal growth conditions yeasts can revert into a semi quiescent survival mode where they build up stores of glycogen and trehalose to strengthen their membranes. Or given really unfavorable conditions yeasts can sporulate and create spores that can easily tolerate a wide range of environmental stresses.

Originally posted on Biochemistry, Molecular, Cellular & Developmental Biology:

Thanks to the BBC for bringing this to my attention. Using photo-activatable chromatophores and some clever fusions combined with computational control algorithms this group was able to partially control gene expression in S.cerevisiae yeast. Could be the start of something big.

http://www.bbc.co.uk/news/science-environment-15598887

Link to the paper:
In silico feedback for in vivo regulation of a gene expression circuit

Andreas Milias-Argeitis1, 4 Sean Summers1, 4 Jacob Stewart-Ornstein2, 4 Ignacio Zuleta2 David Pincus2 Hana El-Samad2 Mustafa Khammash3 John Lygeros1

 

View original