Stuck fermentation triggered by prions

Scientists have discovered the cause of “stuck fermentation” which will enable winemakers to avoid the problem in the future.

Wine and beer

No fermentation, no wine or beer.

According to Science 2.0 a team of researchers has discovered a biochemical communication system behind the problem of “stuck fermentation” encountered by winemakers wherein yeast which should be converting sugar to alcohol and carbon dioxide prematurely shuts down, leaving the remaining sugar to be consumed by bacteria risking spoilage.

The problem has been studied extensively and, for years, biologists have been aware of an ancient biological circuit based in the yeast cell membranes that blocks yeast from using other carbon sources when the sugar glucose is present.

The circuit, known as “glucose repression”, is an efficient processor of sugar and particularly strong in the yeast species Saccharomyces cerevisiae, enabling practical fermentation processes with applications in winemaking, brewing and bread making.

Working through a prion, an abnormally shaped protein capable of self reproduction, the system enables bacteria in fermenting wine to switch yeast from sugar to other food sources without altering the yeast’s DNA.

According to Linda Bisson, a professor in the Department of Viticulture and Enology at U.C. Davis: “The discovery of this process really gives us a clue to how stuck fermentations can be avoided.”

“Our goal now is to find yeast strains that essentially ignore the signal initiated by the bacteria and do not form the prion, but instead power on through the fermentation,” she said.

The researchers found that the glucose repression circuit is sometimes interrupted when bacteria jump-start prion reproduction.

The resulting interference causes the yeast to process carbon sources other than glucose that dramatically slows down the fermentation process until it becomes “stuck”.

The study will enable better control of the fermentation process.

The study will enable better control of the fermentation process.

“This type of prion-based inheritance is useful to organisms when they need to adapt to environmental conditions but not necessarily permanently,” Bisson said.

“In this case, the heritable changes triggered by the prions enable the yeast to also change back to their initial mode of operation if environmental conditions should change again.”

Through the study the researchers were able to demonstrate that the process leading to stuck fermentation benefits both the yeast and bacteria.

As the sugar metabolism slows, conditions in the ferment become more conducive to bacterial growth and the yeast benefits by gaining the ability to metabolise additional carbon sources to glucose thus maintaining and extending their lifespan.

With a clear understanding of this process winemakers should now be better able to avoid stuck fermentations.

“Winemakers may want to alter the levels of sulfur dioxide used when pressing or crushing the grapes, in order to knock out bacteria that can trigger the processes that we now know can lead to a stuck fermentation,” Bisson said.

“They also can be careful about blending grapes from vineyards known to have certain bacterial strains or they could add yeast strains that have the ability to overpower these vineyard bacteria.”

Leave a Reply

Your email address will not be published. Required fields are marked *

Please note that comments are subject to our posting guidelines in accordance with the Defamation Act 2013. Posts containing swear words, discrimination, offensive language and libellous or defamatory comments will not be approved.

Subscribe to our newsletters

Sales Administrator

Ellis Wines
Hanworth, Middx, IU

Sales Support Executive

Davy's
London, UK

Partner Manager – On-trade - Greater London

Maverick Drinks
London/M25 belt, UK

Partner Manager – On-trade - North West

Maverick Drinks
Manchester, UK

Partner Manager – On-trade - West & Wales

Maverick Drinks
Bristol, UK

Partner Manager – On-trade - South East

Maverick Drinks
Brighton, UK

Events Sales Executive

The Drinks Business
Central London, UK

Sale & Operations Manager

Marussia Beverages
Marylebone, London, UK

Pink Rosé Festival

Cannes,France
7th Feb 2018

VinoVision Paris

Paris,France
12th Feb 2018

Vinisud

Montpellier,France
18th Feb 2018
Click to view more

Champagne Masters 2017

The only Champagne blind tasting in the UK, the competition will reward the best wines in the following categories:

The Global Rosé Masters 2017

With wines from the palest of pink to almost ruby red, bone dry to almost cloyingly sweet, reductively handled to barrel-aged, as well as gently spritzy to fully sparkling.

Click to view more