Microbial dynamics, metabolite profiles, and chemical composition in Saccharomyces cerevisiae and Kluyveromyces marxianus Co-culture during solid-state fermentation

The solid-state fermentation (SSF) method is widely used for preparing food and feed, enhancing nutritional value, and producing prebiotics and metabolites. However, the dynamic interactions between microorganisms and metabolite production in fermented feed remain insufficiently understood. This study investigated Saccharomyces cerevisiae and Kluyveromyces marxianus co-culture during SSF feed (NM) preparation. Advanced methods, including 16S rRNA gene sequencing, ITS sequencing, and non-targeted metabolomics analysis, were used to investigate the changes in microflora and metabolites during the fermentation. The comprehensive correlations between these factors were also assessed. The results showed that pH value decreased, macromolecular protein degraded, organic acid content increased, and Saccharomyces, Kluyveromyces, and Lactobacillus dominated at the end of fermentation. Approximately 826 metabolites were identified, among which the levels of arachidonic acid (AA), taurine, L-lysine, D-xylitol, and N-acetylglutamic acid (NAG) were significantly increased. However, the metabolic pathways of arachidonic acid, phenylalanine, and linoleic acid are essential for fermentation. Correlation analysis between bacterial flora and metabolites revealed that Kluyveromyces was positively associated with the abundance of L-lysine, NAG, and AA, while Saccharomyces showed positive correlations with L-lysine, Dxylose, and pantothenic acid. These findings illustrate the dynamic changes in the SSF co-culture of both microorganisms and offer a valuable reference for enhancing the effectiveness and efficiency of feed production through SSF.