scholarly journals Vinification without Saccharomyces: Interacting Osmotolerant and “Spoilage” Yeast Communities in Fermenting and Ageing Botrytised High-Sugar Wines (Tokaj Essence)

2020 ◽  
Vol 9 (1) ◽  
pp. 19
Author(s):  
Hajnalka Csoma ◽  
Zoltán Kállai ◽  
Zsuzsa Antunovics ◽  
Kinga Czentye ◽  
Matthias Sipiczki
Keyword(s):  
Fragment Length Polymorphism ◽  
Sugar Content ◽  
Grape Juice ◽  
Minor Components ◽  
Additional Species ◽  
Spoilage Yeast ◽  
Genetic Segregation ◽  
Spoilage Yeasts ◽  
Molecular Karyotype ◽  
Restriction Fragment Length

The conversion of grape juice to wine starts with complex yeast communities consisting of strains that have colonised the harvested grape and/or reside in the winery environment. As the conditions in the fermenting juice gradually become inhibitory for most species, they are rapidly overgrown by the more adaptable Saccharomyces strains, which then complete the fermentation. However, there are environmental factors that even Saccharomyces cannot cope with. We show that when the sugar content is extremely high, osmotolerant yeasts, usually considered as “spoilage yeasts“, ferment the must. The examination of the yeast biota of 22 botrytised Tokaj Essence wines of sugar concentrations ranging from 365 to 752 g∙L−1 identified the osmotolerant Zygosaccharomyces rouxii, Candida (Starmerella) lactis-condensi and Candida zemplinina (Starmerella bacillaris) as the dominating species. Ten additional species, mostly known as osmotolerant spoilage yeasts or biofilm-producing yeasts, were detected as minor components of the populations. The high phenotypical and molecular (karyotype, mtDNA restriction fragment length polymorphism (RFLP) and microsatellite-primed PCR (MSP-PCR)) diversity of the conspecific strains indicated that diverse clones of the species coexisted in the wines. Genetic segregation of certain clones and interactions (antagonism and crossfeeding) of the species also appeared to shape the fermenting yeast biota.

scholarly journals The Preservative Sorbic Acid Targets Respiration, Explaining the Resistance of Fermentative Spoilage Yeast Species

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Malcolm Stratford ◽  
Cindy Vallières ◽  
Ivey A. Geoghegan ◽  
David B. Archer ◽  
Simon V. Avery
Keyword(s):  
Sorbic Acid ◽  
Yeast Species ◽  
Sugar Content ◽  
Rhodotorula Glutinis ◽  
Soft Drinks ◽  
Effective Control ◽  
Data Set ◽  
Content Type ◽  
Spoilage Yeast ◽  
Spoilage Yeasts

ABSTRACT A small number (10 to 20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like sorbic acid, and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only, and most of these are sorbic acid sensitive and so prevented from causing spoilage. This led us to hypothesize that sorbic acid may specifically inhibit respiration. Tests with respirofermentative yeasts showed that sorbic acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) than during fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables sorbic acid-resistant growth. Sorbic acid inhibited the respiration process more strongly than fermentation. We present a data set supporting a correlation between the level of fermentation and sorbic acid resistance across 191 yeast species. Other weak acids, C2 to C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic acidification. Supporting this, we present evidence that sorbic acid causes production of reactive oxygen species, the formation of petite (mitochondrion-defective) cells, and Fe-S cluster defects. This work rationalizes why yeasts that can grow in sorbic acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favor respiration over fermentation in many spoilage yeasts. IMPORTANCE Spoilage by yeasts and molds is a major contributor to food and drink waste, which undermines food security. Weak acid preservatives like sorbic acid help to stop spoilage, but some yeasts, commonly associated with spoilage, are resistant to sorbic acid. Different yeasts generate energy for growth by the processes of respiration and/or fermentation. Here, we show that sorbic acid targets the process of respiration, so fermenting yeasts are more resistant. Fermentative yeasts are also those usually found in spoilage incidents. This insight helps to explain the spoilage of sorbic acid-preserved foods by yeasts and can inform new strategies for effective control. This is timely as the sugar content of products like soft drinks is being lowered, which may favor respiration over fermentation in key spoilage yeasts.

scholarly journals The preservative sorbic acid targets respiration, explaining the resistance of fermentative spoilage-yeast species

2020 ◽  
Author(s):  
M. Stratford ◽  
C. Vallières ◽  
I.A. Geoghegan ◽  
D.B. Archer ◽  
S.V. Avery
Keyword(s):  
Sorbic Acid ◽  
Yeast Species ◽  
Sugar Content ◽  
Acid Resistance ◽  
Rhodotorula Glutinis ◽  
Weak Acid ◽  
Soft Drinks ◽  
Effective Control ◽  
Spoilage Yeast ◽  
Spoilage Yeasts

ABSTRACTA small number (10-20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like sorbic acid and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only and most of these are sorbic acid-sensitive, so prevented from causing spoilage. This led us to hypothesize that sorbic acid may specifically inhibit respiration. Tests with respiro-fermentative yeasts showed that sorbic acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) compared with fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables sorbic acid-resistant growth. Sorbic acid inhibited the respiration process more strongly than fermentation. We present a dataset supporting a correlation between the level of fermentation and sorbic acid resistance across 191 yeast species. Other weak acids, C2 – C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic acidification. Supporting this, we present evidence that sorbic acid causes production of reactive oxygen species, the formation of petite (mitochondria-defective) cells, and Fe-S cluster defects. This work rationalises why yeasts that can grow in sorbic acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favour respiration over fermentation in many spoilage yeasts.IMPORTANCESpoilage by yeasts and moulds is a major contributor to food and drink waste, which undermines food security. Weak acid preservatives like sorbic acid help to stop spoilage but some yeasts, commonly associated with spoilage, are resistant to sorbic acid. Different yeasts generate energy for growth by the processes of respiration and/or fermentation. Here we show that sorbic acid targets the process of respiration, so fermenting yeasts are more resistant. Fermentative yeasts are also those usually found in spoilage incidents. This insight helps to explain the spoilage of sorbic acid-preserved foods by yeasts and can inform new strategies for effective control. This is timely as sugar content of products like soft drinks is being lowered, which may favour respiration over fermentation in key spoilage yeasts.

Variation in the Promoter Region of the β Fibrinogen Gene Is Associated with Plasma Fibrinogen Levels in Smokers and Non-Smokers

1991 ◽  
Vol 65 (05) ◽  
pp. 487-490 ◽  
Author(s):  
A E Thomas ◽  
F R Green ◽  
C H Kelleher ◽  
H C Wilkes ◽  
P J Brennan ◽  
...  
Keyword(s):  
Heart Disease ◽  
Promoter Region ◽  
Fragment Length Polymorphism ◽  
Fibrinogen Level ◽  
Plasma Fibrinogen ◽  
Plasma Fibrinogen Level ◽  
Healthy Men ◽  
History Of ◽  
General Practices ◽  
Restriction Fragment Length

SummaryWe investigated the association between fibrinogen levels and a HaeIII restriction fragment length polymorphism located at −453 bp from the start of transcription of the β fibrinogen gene. 292 healthy men aged 45 to 69 years, recruited from general practices throughout Britain, were studied. None had a history of ischaemic heart disease. 41.1% (120) were smokers and fibrinogen levels were higher in this group. The frequency of the noncutting allele (designated H2) was 0.19 and was the same in smokers and non-smokers. The H2 allele was associated with elevated levels of fibrinogen in both smokers and non-smokers and the effect of genotype was similar in both groups. After smoking, HaeIII genotype was the strongest predictor of fibrinogen levels and explained 3.1% of the variance in fibrinogen levels. These results confirm earlier studies that variation at the fibrinogen locus contributes to the between-individual differences in plasma fibrinogen level.

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