Project description:This study describes a transcriptome-phenotype matching approach in which the starter L. lactis MG1363 was fermented under a variety of conditions that differed in the levels of oxygen and/or salt, as well as the fermentation pH and temperature. Samples derived from these fermentations in the exponential phase of bacterial growth were analyzed by full-genome transcriptomics and the assessment of heat and oxidative stress phenotypes. Variations in the fermentation conditions resulted in up to 1000-fold differences in survival during heat and oxidative stress. More specifically, aeration during fermentation induced protection against heat stress, whereas a relatively high fermentation temperature resulted in enhanced robustness towards oxidative stress. Concomitantly, oxygen levels and fermentation temperature induced differential expression of markedly more genes when compared with the other fermentation parameters. Correlation analysis of robustness phenotypes and gene expression levels revealed transcriptome signatures for oxidative and/or heat stress survival, including the metC-cysK operon involved in methionine and cysteine metabolism. To validate this transcriptome-phenotype association we grew L. lactis MG1363 in the absence of cysteine which led to enhanced robustness towards oxidative stress. Conclusions Overall, we demonstrated the importance of careful selection of fermentation parameters prior to industrial processing of starter cultures. Furthermore, established stress genes as well as novel genes were associated with robustness towards heat and/or oxidative stress. Assessment of the expression levels of this group of genes could function as an indicator for enhanced selection of fermentation parameters resulting in improved robustness during spray drying. The increased robustness after growth without cysteine appeared to confirm the role of expression of the metC-cysK operon as an indicator of robustness and suggests that sulfur amino acid metabolism plays a pivotal role in oxidative stress survival.
Project description:This study describes a transcriptome-phenotype matching approach in which the starter L. lactis MG1363 was fermented under a variety of conditions that differed in the levels of oxygen and/or salt, as well as the fermentation pH and temperature. Samples derived from these fermentations in the exponential phase of bacterial growth were analyzed by full-genome transcriptomics and the assessment of heat and oxidative stress phenotypes. Variations in the fermentation conditions resulted in up to 1000-fold differences in survival during heat and oxidative stress. More specifically, aeration during fermentation induced protection against heat stress, whereas a relatively high fermentation temperature resulted in enhanced robustness towards oxidative stress. Concomitantly, oxygen levels and fermentation temperature induced differential expression of markedly more genes when compared with the other fermentation parameters. Correlation analysis of robustness phenotypes and gene expression levels revealed transcriptome signatures for oxidative and/or heat stress survival, including the metC-cysK operon involved in methionine and cysteine metabolism. To validate this transcriptome-phenotype association we grew L. lactis MG1363 in the absence of cysteine which led to enhanced robustness towards oxidative stress. Conclusions Overall, we demonstrated the importance of careful selection of fermentation parameters prior to industrial processing of starter cultures. Furthermore, established stress genes as well as novel genes were associated with robustness towards heat and/or oxidative stress. Assessment of the expression levels of this group of genes could function as an indicator for enhanced selection of fermentation parameters resulting in improved robustness during spray drying. The increased robustness after growth without cysteine appeared to confirm the role of expression of the metC-cysK operon as an indicator of robustness and suggests that sulfur amino acid metabolism plays a pivotal role in oxidative stress survival. two connected loops, both containing samples derived on a single day (sample 1-6, sample 7-13)
Project description:This project characterizes the temporal dynamics of microbial communities and functional potential in strong-flavor Daqu (a traditional Chinese fermentation starter) across a 4-month storage period.
Project description:To study the characteristics of proteins in Chinese Chixiang-flavor Baijiu fermentation, a label-free quantitative proteomics approach was established to identify proteins in Jiuqu starter and fermented grains.
2019-06-11 | PXD014221 |
Project description:Studies on Chinese traditional fermentation starter,Jiuyao.
Project description:Undaria pinnatifida, a representative brown macroalga, is limited in high-value food applications due to its dense cell wall structure, pronounced marine odor, and inefficient conventional processing. In this study, a controlled fermentation strategy was established using different lactic acid bacterial starters with Undaria pinnatifida slurry as the substrate. Milk starter fermentation exhibited a predominance of Streptococcus, with annotated enrichment in propanoate metabolism and branched-chain amino acid degradation. These metabolic signatures coincided with higher abundances of esters and methyl-branched volatiles correlated with roasty and fruity sensory notes. In comparison, kimchi starter fermentation was abundant in Lactiplantibacillus, where starch–sucrose and arginine–proline metabolic pathways were enriched. The observed accumulation of furanones and hexenal was closely associated with caramel-like sweetness. This study characterizes lactic acid bacteria–correlated metabolic patterns underlying the formation of quality, offering valuable references for the controlled bioprocessing of brown macroalgae.
Project description:Growth of L. cremoris NCDO712 was not altered when manganese is omitted from its defined medium. This study was conducted in order to compare protein requirements of Lactococcus cremoris NCDO712 to grow in the presence or absence of manganese in defined medium (1% lactose). The majority of protein adaptation involves upregulation of Mn transporters and to a lesser extent various NADH-dependent proteins. Such adaptation is highly relevant for starter culture in dairy fermentation where manganese is limited and NADH homeostasis determines the formation of volatiles during long-term incubation e.g. cheese ripening.
2022-05-16 | PXD030123 | Pride
Project description:Amplicon sequencing of Chinese liquor fermentation starter culture (its)
| PRJNA1064014 | ENA
Project description:Amplicon sequencing of Chinese liquor fermentation starter culture (16s)