Decoding microbiota and metabolite transformation in inoculated fermented suansun using metagenomics, GC-MS, non-targeted metabolomics, and metatranscriptomics:Impacts of different Lactobacillus plantarum strains.

Using metagenomics, GC-MS, non-targeted metabolomics, and metatranscriptomics, we investigated the microbial communities and metabolites in two different Lactobacillus plantarum fermentations. Metagenomics revealed Weissella cibaria dominantly contributed to the DACN766-fermented suansun (LPS1) and Lactiplantibacillus pentosus to the DACN760-fermented suansun (LPS2). GC-MS identified 38 and 40 flavor compounds in LPS1 and LPS2, respectively, with p-cresol, 4-hydroxybenzaldehyde, acetic acid, hexanal, and propionic acid crucial for aroma development. LPS2 exhibited higher levels of p-cresol and acetic acid, contributing to its stronger sour and pungent flavors, which was achieved by regulating many metabolisms like glycolysis and tyrosine metabolism. In contrast, Weissella cibaria plays a role in mitigating off-flavors, resulting in a milder flavor profile in LPS1. Non-targeted metabolomics indicated 70.78% of differential metabolites were upregulated in LPS1. Conversely, the elevated expression of tryptophan and tyrosine underscores the more pronounced sour and odor-producing characteristics observed in LPS2. Metatranscriptomics highlighted the regulation of genes like XFA, XFT, and XFM, which inhibit the formation of the precursors of p-cresol and indole in LPS2. This integrated multi-omics analysis provides deep insights into the fermentation dynamics, facilitating the targeted selection of Lactobacillus plantarum strains with flavor-regulating capabilities.