Pichia anomala enhances the growth and lactic acid production of Leuconostoc citreum: Synergistic improvement for sweet sorghum silage quality.

To address the pressing need for improving the silage quality of sweet sorghum, this study aims to establish aPichia anomala-Lactic acid bacteria (LAB) consortium suitable for the sweet sorghum silage system and to elucidate its synergistic mechanism through untargeted metabolomics. The optimal P. anomala-Leuconostoc citreum consortium was obtained through a membership function analysis based on indicators of organic acids and antifungal metabolites. Compared to L. citreum monoculture, the co-culture enhanced L. citreum viable cell count and lactic acid (LA) production by 35.80% and161.34%, respectively. Untargeted metabolomics analysis of differential metabolites related to L. citreum growth and LA synthesis revealed upregulation of amino acids and their derivatives (10), bioactive peptides (4), vitamins (4), and organic acids (2). This metabolic profilereveals the role of P. anomala in enhancing L. citreum growth and LA synthesis by providing key growth factors and LA precursors. During ensiling, the P. anomala-L. citreum consortium significantlyslowedthe loss of dry matter (DM) and water-soluble carbohydrate (WSC), and reducedthe content of fiber components and structural polysaccharides (P < 0.05). The consortium also effectively suppressed the accumulation of ammonia nitrogen (AN) and propionic acid (PPA), while significantly increasing the contents of crude protein (CP), LA, and acetic acid (AA) (P < 0.05). These findings provide a novel insight for developing high-performance yeast-LAB consortia for the improvement of biomass silage quality.