There is a great diversity of indigenous microorganisms in flour,the number of which increased greatly during long-term dough fermentation,affecting dough fermentation and product quality.In this study,the diversity o...There is a great diversity of indigenous microorganisms in flour,the number of which increased greatly during long-term dough fermentation,affecting dough fermentation and product quality.In this study,the diversity of indigenous bacteria in fermented dough inoculated with single Saccharomyces cerevisiae Y10 strain,Torulaspora delbrueckii Y22 strain and their co-culture was revealed by Illumina MiSeq sequencing.Compared with the dough without yeast inoculation,the bacteria diversity in yeast fermented dough was lower after 12 h fermentation.However,the abundance of lactic acid bacteria(LAB)in the dough inoculated with yeast was higher than that in dough without any yeast inoculated.Similar community structures of bacteria were found in doughs inoculated with different yeast,but their abundance were different.The abundance of the genus Clostridium in doughs inoculated with single S.cerevisiae Y10 was lower than non-inoculated dough,doughs inoculated with T.delbrueckii Y22 and co-culture of S.cerevisiae Y10 and T.delbrueckii Y22 at the same fermentation stage.In comparison with the dough without yeast inoculation,the presence of T.delbrueckii Y22 and the co-culture of S.cerevisiae Y10 and T.delbrueckii Y22 decreased the relative abundance of Staphylococcus,Cronobacter and Enterobacter in fermented dough.Furthermore,the relative abundance of Komagataeibacter increased in the presence of co-culture of S.cerevisiae Y10 and T.delbrueckii Y22.The results of this study suggested that the diversity of indigenous bacteria during dough fermentation was greatly influenced by the starter strain.展开更多
Soy whey is a liquid by-product generated from tofu production and it is often discarded as wastewater after it is generated.Previous studies have shown that out of the three branched-chain amino acids,isoleucine was ...Soy whey is a liquid by-product generated from tofu production and it is often discarded as wastewater after it is generated.Previous studies have shown that out of the three branched-chain amino acids,isoleucine was found to have an inhibitory effect on Torulaspora delbrueckii Biodiva during soy whey fermentation.In this study,a comparison between isoleucine and leucine was carried out to ascertain how these two structural isomers could affect the growth and metabolism of T.delbrueckii Biodiva at various concentrations(40,80 and 160 mg nitrogen/L).In general,amino acid supplementation sped up the fermentation process relative to unsupplemented samples.Even though glycerol and ethanol production were enhanced in all isoleucine supplemented samples in comparison to unsupplemented samples,isoleucine supplementation resulted in slower yeast growth at day 1 and slower sucrose hydrolysis regardless of the concentration supplemented.As for leucine supplementation,there was no impact on yeast growth,glycerol and ethanol production but sucrose hydrolysis was enhanced in comparison to the unsupplemented samples.Increasing isoleucine and leucine supplementation resulted in corresponding increase in active amyl alcohol and isoamyl alcohol production respectively,but isoleucine had a stimulating effect on increasing the production of other higher alcohols while leucine had an inhibitory effect on the production of other higher alcohols.Therefore,even though isoleucine and leucine are structural isomers with the positional difference of only one methyl group,the impact on the yeast metabolism and growth is visibly different.展开更多
基金sponsored by Natural Science Foundation of Henan Province(202300410113)Innovation Fund Plan of Henan University of Technology(2020ZKCJ20).
文摘There is a great diversity of indigenous microorganisms in flour,the number of which increased greatly during long-term dough fermentation,affecting dough fermentation and product quality.In this study,the diversity of indigenous bacteria in fermented dough inoculated with single Saccharomyces cerevisiae Y10 strain,Torulaspora delbrueckii Y22 strain and their co-culture was revealed by Illumina MiSeq sequencing.Compared with the dough without yeast inoculation,the bacteria diversity in yeast fermented dough was lower after 12 h fermentation.However,the abundance of lactic acid bacteria(LAB)in the dough inoculated with yeast was higher than that in dough without any yeast inoculated.Similar community structures of bacteria were found in doughs inoculated with different yeast,but their abundance were different.The abundance of the genus Clostridium in doughs inoculated with single S.cerevisiae Y10 was lower than non-inoculated dough,doughs inoculated with T.delbrueckii Y22 and co-culture of S.cerevisiae Y10 and T.delbrueckii Y22 at the same fermentation stage.In comparison with the dough without yeast inoculation,the presence of T.delbrueckii Y22 and the co-culture of S.cerevisiae Y10 and T.delbrueckii Y22 decreased the relative abundance of Staphylococcus,Cronobacter and Enterobacter in fermented dough.Furthermore,the relative abundance of Komagataeibacter increased in the presence of co-culture of S.cerevisiae Y10 and T.delbrueckii Y22.The results of this study suggested that the diversity of indigenous bacteria during dough fermentation was greatly influenced by the starter strain.
基金supported,in part,by a research grant from Singapore Ministry of Education(WBS No.R160-000-664-114).
文摘Soy whey is a liquid by-product generated from tofu production and it is often discarded as wastewater after it is generated.Previous studies have shown that out of the three branched-chain amino acids,isoleucine was found to have an inhibitory effect on Torulaspora delbrueckii Biodiva during soy whey fermentation.In this study,a comparison between isoleucine and leucine was carried out to ascertain how these two structural isomers could affect the growth and metabolism of T.delbrueckii Biodiva at various concentrations(40,80 and 160 mg nitrogen/L).In general,amino acid supplementation sped up the fermentation process relative to unsupplemented samples.Even though glycerol and ethanol production were enhanced in all isoleucine supplemented samples in comparison to unsupplemented samples,isoleucine supplementation resulted in slower yeast growth at day 1 and slower sucrose hydrolysis regardless of the concentration supplemented.As for leucine supplementation,there was no impact on yeast growth,glycerol and ethanol production but sucrose hydrolysis was enhanced in comparison to the unsupplemented samples.Increasing isoleucine and leucine supplementation resulted in corresponding increase in active amyl alcohol and isoamyl alcohol production respectively,but isoleucine had a stimulating effect on increasing the production of other higher alcohols while leucine had an inhibitory effect on the production of other higher alcohols.Therefore,even though isoleucine and leucine are structural isomers with the positional difference of only one methyl group,the impact on the yeast metabolism and growth is visibly different.
