Screening and synergistic evaluation of microbial strains for optimal bioconversion of potato waste via solid‐state fermentation

BACKGROUND Potato peel waste (PPW) is one of the main byproducts of food processing, and while solid‐state fermentation has been proposed for its valorization, comparative evaluations of taxonomically diverse microorganisms and rationally selected dual‐strain co‐cultures on PPW remain limited. This study compared seven microbial strains under standardized fermentation conditions and evaluated selected bacterial–bacterial, bacterial–yeast, bacterial–filamentous fungus, and yeast–filamentous fungus co‐cultures. RESULTS Monocultures differed substantially in crude protein (CP) enrichment, acidity, pH, protease activity, viability, and fiber fractions. Pediococcus acidilactici produced the highest monoculture CP increase (48.9%), while titratable acidity was positively associated with CP enrichment across the seven monocultures ( r = 0.874, P = 0.010). Among the tested dual‐strain treatments, the Bacillus subtilis – Saccharomyces cerevisiae bacterial–yeast co‐culture produced the highest final CP concentration (157.3 g kg −1 ), corresponding to a 58.9% increase relative to the unfermented control, and reduced neutral detergent fiber concentration by 37.5% under the tested conditions. These results indicate that co‐culture performance depended on the specific strain combination and cannot be inferred from cell viability alone. CONCLUSION These findings indicate that metabolically complementary microbial consortia can yield superior bioconversion outcomes compared to single‐strain fermentation systems, providing a framework for the development of multi‐strain strategies for the efficient conversion of agro‐industrial lignocellulosic wastes into protein‐enriched animal feed components.