Bioturbation analysis of microbial communities and flavor metabolism in a high-yielding cellulase Bacillus subtilis biofortified Daqu.

In this study, a fortified Daqu (FF Daqu) was prepared using high cellulase-producing Bacillus subtilis, and the effects of in situ fortification on the physicochemical properties, flavor, active microbial community and metabolism of Daqu were analyzed. The saccharification power, liquefaction power, and cellulase activity of the FF Daqu were significantly increased compared with that of the traditional Daqu (CT Daqu). The overall differences in flavor components and their contents were not significant, but the higher alcohols were lower in FF Daqu. The relative abundance of dominant active species in FF Daqu was 85.08% of the total active microbiota higher than 63.42% in CT Daqu, and the biomarkers were Paecilomyces variotii and Aspergillus cristatus, respectively. The enzymes related to starch and sucrose metabolic pathways were up-regulated and expressed in FF Daqu. In the laboratory level simulation of baijiu brewing, the yield of baijiu was increased by 3.36% using FF Daqu.

Combined microbiome and metabolomics analysis of Taorong-type baijiu high-temperature Daqu and medium-temperature Daqu.

Background: Daqu is an essential starter for baijiu brewing in China. However, the microbial enrichment and metabolic characteristics of Daqu formed at different fermentation temperatures are still unclear. Methods: High-throughput sequencing technology and the non-targeted metabolomics were used to compare the microbial communities and metabolites of Taorong-type high-temperature Daqu and middle-temperature Daqu. In this study, the relationship between microorganisms and metabolites was established. Results: The study found that the composition and metabolites of the microbial community differed due to the difference in Daqu-making temperature. The bacterial diversity of Taorong-type high-temperature Daqu was higher than that of middle-temperature Daqu, while the fungal community diversity of Taorong-type middle-temperature Daqu was higher than that of high temperature Daqu. A total of 1,034 differential metabolites were screened from the two types of Daqu, and 76 metabolites with significant differences were detected (P < 0.001 and variable importance in projection (VIP) > 1.15). Tetraacetylethylenediamine is the metabolite with the largest differential fold among the 76 differential metabolites, which can be used as a potential marker metabolite of high-temperature Daqu. Conclusion: This study helps elucidate the microbial assembly mechanisms and functional expression under different processing conditions through a further understanding of the composition and metabolic profile differences of different types of Daqu microflora in Taorong-type baijiu.

Screening and identification of high yield tetramethylpyrazine strains in Nongxiangxing liquor Daqu and study on the mechanism of tetramethylpyrazine production.

BACKGROUND: There are few reports on the breeding of high-yielding tetramethylpyrazine (TTMP) strains in strong-flavor Daqu. In addition, studies on the mechanism of TTMP production in strains are mostly based on common physiological and biochemical indicators, and there is no report on RNA level. Therefore, in this study, a strain with high production of TTMP was screened out from strong-flavor liquor, and transcriptome sequencing analysis was performed to analyze its key metabolic pathways and key genes, and to infer the mechanism of TTMP production in the strain. RESULTS: In this study, a strain with a high yield of tetramethylpyrazine (TTMP) was screened out, and the yield was 29.83 µg mL-1 . The identified strain was Bacillus velezensis, which could increase the content of TTMP in liquor by about 88%. After transcriptome sequencing, a total of 1851 differentially expressed genes were screened, including 1055 up-regulated genes and 796 down-regulated genes. Three pathways related to the production of TTMP were identified by gene ontology (GO) annotation and COG annotation, including carbohydrate metabolism, cell movement and amino acid metabolism. The key genes of TTMP were analyzed, and the factors that might regulate the production of TTMP, such as the transfer of uracil phosphate ribose and glycosyltransferase, were obtained. CONCLUSIONS: A strain of B. velezensis with high TTMP production was screened and identified in strong-flavor Daqu for the first time. The yield of TTMP was 29.83 µg mL-1 , which increased the TTMP content in liquor by 88%. The key metabolic pathways of TTMP production in the strain were obtained: carbohydrate metabolism, cell movement and amino acid metabolism, and the key regulatory genes of each pathway were found, which complemented the gap in gene level in the production regulation of the strain, and provided a theoretical basis for the subsequent study of TTMP in liquor. © 2023 Society of Chemical Industry.

The role of wheat embryo globulin nutrients in improving cognitive dysfunction in AD rats.

Neuroinflammation and intestinal microbiota cause pathological progression of Alzheimer's disease (AD), leading to neurodegeneration and cognitive decline. This study investigates the effects of wheat embryo globulin nutrient (WEGN) on depression, neuroinflammation, and intestinal microbial disorder caused by AD and its protective mechanism on cognitive impairment. Results demonstrated that rats in the WEGN group have lower feed intake but higher body weight than those in the control group. Notably, rats in the WEGN group have a higher number of cross grids and uprights and a smaller amount of fecal particles than those in the control group. Biochemical examinations revealed that rats in the WEGN group had lower expression of interleukin-1ß, interleukin-6, and tumor necrosis factor α in hippocampus tissue and the expression of genes and proteins related to the TLR4/MyD88/NF-κB signaling pathway in AD rats was down-regulated compared to those in the control group. The 16S rRNA gene sequencing results demonstrated that WEGN treatment inhibits the increase of Erysipelotrichaceae, Erysipelatoclostridium, Erysipelotrichaceae, Corynebacterium, and Frisingicoccus, and the reduction of Lactobacillus in AD rats. WEGN has potential value as a practical food in alleviating neuroinflammation-related diseases such as AD.

Profiling the composition and metabolic activities of microbial community in fermented grain for the Chinese strong-flavor Baijiu production by using the metatranscriptome, high-throughput 16S rRNA and ITS gene sequencings.

The composition and function of microbial community analyzed by sequencing 16S rRNA/ITS gene amplicons (DNA level) were compared with those derived by using metatranscriptome sequencing (RNA level) from the same fermented grain (FG) sample, which obtained from the key fermentation time point during the Chinese strong-flavor Baijiu (CSFB) production process. The results showed that the fungi with the highest relative abundance was Saccharomyces (RNA: 83.15%, DNA: 89.74%) at the two levels. The most abundant bacterium was Kroppenstedtia (37.09%) detected only at the DNA level, while it was Streptococcus (93.75%) at the RNA level, indicating that the structures of prokaryotic communities at the two levels were quite different. For the microbial functions, a large proportion of genes of FG microorganisms related to "Metabolism" function were observed both by using PICRUSt2 analysis (DNA level) and metatranscriptome analysis (RNA level), and especially enriched in "Carbohydrate metabolism". While the proportions of genes involved in some functions were different, such as "Replication and repair", "Membrane transport" and "Environmental adaptation", with high proportions of genes involved in at the DNA level when compared those at the RNA level. Furthermore, Saccharomyces cerevisiae was the most active microbe in the top15 pathways, followed by Torulaspora dellbrueckii. During the conversion of starch to ethanol, S. cerevisiae showed high metabolic capacity, and cooperated with other microorganisms to convert pyruvate to acetaldehyde directly or through acetyl-CoA and acetate, and then acetaldehyde to ethanol. As far as we know, this is a first study to profile the microbial community and metabolic features in FG of CSFB by using a combination of DNA- and RNA- based technologies. Our findings could provide useful insights for further understanding the active microbial function, metabolic pathways and fermentation mechanism in the FG ecosystem during CSFB fermentation.