Gut-Derived Lactic Acid Bacteria from Cotton Bollworm Exhibit Efficient Gossypol Degradation and Probiotic Potential During Solid-State Fermentation of Cottonseed Meal

Cottonseed meal (CSM), an important protein-rich feed ingredient, faces limited utilization in livestock diets due to the presence of free gossypol (FG)—a potent antinutritional toxin. This study aimed to isolate FG-degrading bacteria from the cotton bollworm, Helicoverpa armigera, and to evaluate their potential as probiotics in vitro. Eleven gossypol-tolerant strains were isolated from the gut of Helicoverpa armigera larvae using a screening medium containing gossypol as the sole carbon source. Among these, four lactic acid bacteria strains—Pediococcus acidilactici GM-NP, Pediococcus acidilactici GM-P, Enterococcus faecalis GM-6, and Weissella confusa GM-2—were selected for further investigation of their gossypol degradation capacity and probiotic potential. Probiotic characterization revealed that all strains exhibited tolerance to gastrointestinal fluids and bile salts, safe γ-hemolysis, and strong auto-aggregation, cell surface hydrophobicity, and antimicrobial activity. Solid-state fermentation of CSM with these strains reduced FG content by more than 50%, increased crude protein by over 6%, and elevated acid-soluble protein content by more than 70%, thereby effectively enhancing the nutritional quality of CSM. This study is the first to demonstrate that bacterial isolates from the gut of Helicoverpa armigera possess concurrent high-efficiency gossypol degradation and probiotic properties, providing a theoretical foundation for developing novel probiotic resources and promoting the safe utilization of CSM.