The eisosomes contribute to acid tolerance of yeast by maintaining cell membrane integrity.

Microbes have evolved multiple mechanisms to resist environmental stresses, which are regulated in complex and delicate ways. Though the role of cell membranes in acid resistance from the perspective of physicochemical properties and membrane proteins has been deeply studied, the function of eisosomes is still in its infancy. In this study, we firstly reported the dynamic changes of eisosomes under acid stress and the decreased acid tolerance of yeasts caused by eisosome disruption.

Application Potential of Baijiu Non- Yeast in Winemaking Through Sequential Fermentation With .

To explore the potential application of non- yeasts screened from Baijiu fermentation environment in winemaking, the effect of four Baijiu non- yeasts (two and two ) sequentially fermented with on the physicochemical parameters and volatile compounds of wine was analyzed. The results indicated that there was no obvious antagonism between and or in sequential fermentations, and all strains could be detected at the end of alcoholic fermentation. Compare with pure fermentation, sequential fermentations significantly reduced higher alcohols, fatty acids, and ethyl esters and increased acetate esters; sequential fermentations reduced the contents of C6 alcohols, total higher alcohols, fatty acids, and ethyl esters and significantly increased the contents of acetate esters (especially ethyl acetate and 3-methylbutyl acetate).

Gene, the GATA Transcription Activator, Regulates the Production of Higher Alcohol during Wheat Beer Fermentation by .

Uncoordinated carbon-nitrogen ratio in raw materials will lead to excessive contents of higher alcohols in alcoholic beverages. The effect of gene, the GATA transcription activator, on higher alcohol biosynthesis was investigated to clarify the mechanism of regulating higher alcohol metabolism under high concentrations of free amino nitrogen (FAN). The availability of FAN by strain SDT1K with a double-copy deletion was 28.

Identification of Core Regulatory Genes and Metabolic Pathways for the -Propanol Synthesis in .

The -propanol produced by has a remarkable effect on the taste and flavor of Chinese Baijiu. The -propanol metabolism-related genes were deleted to evaluate the role in the synthesis of -propanol to ascertain the key genes and pathways for the production of -propanol by . The results showed that 3, 1, 6, 1, 5, and 082 were the key genes affecting the -propanol metabolism in yeast.

Comparative transcriptome analysis reveals the key regulatory genes for higher alcohol formation by yeast at different α-amino nitrogen concentrations.

Higher alcohols are important flavor substance in alcoholic beverages. The content of α-amino nitrogen (α-AN) in the fermentation system affects the formation of higher alcohols by Saccharomyces cerevisiae. In this study, the effect of α-AN concentration on the higher alcohol productivity of yeast was explored, and the mechanism of this effect was investigated through metabolite and transcription sequence analyses.

Effect of the Deletion of Genes Related to Amino Acid Metabolism on the Production of Higher Alcohols by .

The higher alcohols produced by exert remarkable influence on the taste and flavour of Chinese Baijiu. In order to study the regulation mechanism of amino acid metabolism genes on higher alcohol production, eight recombinant strains with amino acid metabolism gene deletion were constructed. The growth, fermentation performance, higher alcohol production, and expression level of genes in recombinant and original 5 strains were determined.

Enhanced Production of Ethyl Lactate in by Genetic Modification.

Ethyl lactate is an important flavor substance in baijiu, and it is also one of the common raw materials in the production of flavors and spices. In this study, we first established the ethyl lactate biosynthesis pathway in α(L) by introducing propionyl coenzyme A transferase () and alcohol acyltransferase (), and the results showed that strain α(L)-CP-Ae produced the most ethyl lactate 239.53 ± 5.

Increased Acetate Ester Production of Polyploid Industrial Brewer's Yeast Strains via Precise and Seamless "Self-cloning" Integration Strategy.

Background: Enhancing the industrial yeast strains ethyl acetate yield through a precise and seamless genetic manipulation strategy without any extraneous DNA sequences is an essential requisite and significant demand.

Objectives: For increasing the ethyl acetate yield of industrial brewer's yeast strain, all the alleles were overexpressed through "self-cloning" integration strategy.

Material And Methods: strain DH5α was utilized for plasmid construction.

Construction of industrial baker's yeast with high level of cAMP.

Cyclic adenosine monophosphate (cAMP) plays an important role in modulating the activity of microbe cell. In this study, PKA (protein kinase A) activity was weakened through truncation of TPK2 promoter (-150 bp and -300 bp) and gene deletion of BCY1 (encodes the regulatory subunit of PKA), TPK1 and TPK3, generating strains BY9a-T2-150 and BY9a-T2-300, respectively. High-performance liquid chromatography analysis showed cAMP levels in BY9a-T2-150 and BY9a-T2-300 were increased by 5- and 18-fold, respectively, compared with that of parent strain, BY9a.

Identification by comparative transcriptomics of core regulatory genes for higher alcohol production in a top-fermenting yeast at different temperatures in beer fermentation.

Undesirable flavor caused by excessive higher alcohols restrains the development of the wheat beer industry. To clarify the regulation mechanism of the metabolism of higher alcohols in wheat beer brewing by the top-fermenting yeast Saccharomyces cerevisiae S17, the effect of temperature on the fermentation performance and transcriptional levels of relevant genes was investigated. The strain S17 produced 297.

Modulating acetate ester and higher alcohol production in Saccharomyces cerevisiae through the cofactor engineering.

Flavor production by esters or by higher alcohols play a key role in the sensorial quality of fermented alcoholic beverages. In Saccharomyces cerevisiae cells, the syntheses of esters and higher alcohols are considerably influenced by intracellular CoA levels catalyzed by pantothenate kinase. In this work, we examined the effects of cofactor CoA and acetyl-CoA synthesis on the metabolism of esters and higher alcohols.

Improved xylose tolerance and 2,3-butanediol production of by directed evolution of and the mechanisms revealed by transcriptomics.

Background: The biological production of 2,3-butanediol from xylose-rich raw materials from is a low-cost process. , an encoding gene of the sigma factor, is the key element in global transcription machinery engineering and has been successfully used to improve the fermentation with . However, whether it can regulate the tolerance in remains unclear.

PGK1 Promoter Library for the Regulation of Acetate Ester Production in Saccharomyces cerevisiae during Chinese Baijiu Fermentation.

Appropriate concentrations and proportion of acetate esters and higher alcohols improve the quality of Chinese Baijiu. To regulate the concentrations of acetate esters in Chinese Baijiu, we constructed a PGK1 promoter library through error-prone PCR. Then, we used an enhanced green fluorescent protein as a reporter to characterize the activities of PGK1p mutants.

Overexpression of SNF4 and deletions of REG1- and REG2-enhanced maltose metabolism and leavening ability of baker's yeast in lean dough.

Maltose metabolism of baker's yeast (Saccharomyces cerevisiae) in lean dough is suppressed by the glucose effect, which negatively affects dough fermentation. In this study, differences and interactions among SNF4 (encoding for the regulatory subunit of Snf1 kinase) overexpression and REG1 and REG2 (which encodes for the regulatory subunits of the type I protein phosphatase) deletions in maltose metabolism of baker's yeast were investigated using various mutants. Results revealed that SNF4 overexpression and REG1 and REG2 deletions effectively alleviated glucose repression at different levels, thereby enhancing maltose metabolism and leavening ability to varying degrees.

Gradual enhancement of ethyl acetate production through promoter engineering in chinese liquor yeast strains.

As content and proportion of ethyl acetate is critical to the flavor and quality of beverages, the concise regulation of the ethyl acetate metabolism is a major issue in beverage fermentations. In this study, for ethyl acetate yield regulation, we finely modulated the expression of ATF1 through precise and seamless insertion of serially truncated PGK1 promoter from the 3' end by 100bp steps in the Chinese liquor yeast, CLy12a. The three engineered promoters carrying 100-, 200-, and 300-bp truncations exhibited reduced promoter strength but unaffected growth.

Functional analysis of the global repressor Tup1 for maltose metabolism in Saccharomyces cerevisiae: different roles of the functional domains.

Background: Tup1 is a general transcriptional repressor of diverse gene families coordinately controlled by glucose repression, mating type, and other mechanisms in Saccharomyces cerevisiae. Several functional domains of Tup1 have been identified, each of which has differing effects on transcriptional repression. In this study, we aim to investigate the role of Tup1 and its domains in maltose metabolism of industrial baker's yeast.

Regulation of Saccharomyces cerevisiae genetic engineering on the production of acetate esters and higher alcohols during Chinese Baijiu fermentation.

Acetate esters and higher alcohols greatly influence the quality and flavor profiles of Chinese Baijiu (Chinese liquor). Various mutants have been constructed to investigate the interactions of ATF1 overexpression, IAH1 deletion, and BAT2 deletion on the production of acetate esters and higher alcohols. The results showed that the overexpression of ATF1 under the control of the PGK1 promoter with BAT2 and IAH1 double-gene deletion led to a higher production of acetate esters and a lower production of higher alcohols than the overexpression of ATF1 with IAH1 deletion or overexpression of ATF1 with BAT2 deletion.

Reduced production of diacetyl by overexpressing BDH2 gene and ILV5 gene in yeast of the lager brewers with one ILV2 allelic gene deleted.

Diacetyl causes an unwanted buttery off-flavor in lager beer. The production of diacetyl is reduced by modifying the metabolic pathway of yeast in the beer fermentation process. In this study, BDH2 and ILV5 genes, coding diacetyl reductase and acetohydroxy acid reductoisomerase, respectively, were expressed using a PGK1 promoter in Saccharomyces cerevisiae, which deleted one ILV2 allelic gene.

Enhanced leavening properties of baker's yeast by reducing sucrase activity in sweet dough.

Leavening ability in sweet dough is required for the commercial applications of baker's yeast. This property depends on many factors, such as glycolytic activity, sucrase activity, and osmotolerance. This study explored the importance of sucrase level on the leavening ability of baker's yeast in sweet dough.

MAL62 overexpression and NTH1 deletion enhance the freezing tolerance and fermentation capacity of the baker's yeast in lean dough.

Background: Trehalose is related to several types of stress responses, especially freezing response in baker's yeast (Saccharomyces cerevisiae). It is desirable to manipulate trehalose-related genes to create yeast strains that better tolerate freezing-thaw stress with improved fermentation capacity, which are in high demand in the baking industry.

Results: The strain overexpressing MAL62 gene showed increased trehalose content and cell viability after prefermention-freezing and long-term frozen.

Reduced production of ethyl carbamate for wine fermentation by deleting CAR1 in Saccharomyces cerevisiae.

Ethyl carbamate (EC), a pluripotent carcinogen, is mainly formed by a spontaneous chemical reaction of ethanol with urea in wine. The arginine, one of the major amino acids in grape musts, is metabolized by arginase (encoded by CAR1) to ornithine and urea. To reduce the production of urea and EC, an arginase-deficient recombinant strain YZ22 (Δcarl/Δcarl) was constructed from a diploid wine yeast, WY1, by successive deletion of two CAR1 alleles to block the pathway of urea production.

Effects of SNF1 on Maltose Metabolism and Leavening Ability of Baker's Yeast in Lean Dough.

Maltose metabolism of baker's yeast (Saccharomyces cerevisiae) in lean dough is negatively influenced by glucose repression, thereby delaying the dough fermentation. To improve maltose metabolism and leavening ability, it is necessary to alleviate glucose repression. The Snf1 protein kinase is well known to be essential for the response to glucose repression and required for transcription of glucose-repressed genes including the maltose-utilization genes (MAL).

Effects of GLC7 and REG1 deletion on maltose metabolism and leavening ability of baker's yeast in lean dough.

Maltose metabolism and leavening ability of baker's yeast (Saccharomyces cerevisiae) in lean dough is negatively influenced by glucose repression. To improve maltose metabolism and leavening ability, it is necessary to alleviate glucose repression. In this study, we focus on the effects of regulators (GLC7 encoding the catalytic and REG1 encoding the regulatory subunits of protein phosphatase type 1) of glucose repression on maltose metabolism and leavening ability of baker's yeast in lean dough.