Project description:<p>Background The gut microbiota plays a significant role in modulating the growth and function of host muscle, and microbiota transplantation experiments provide compelling evidence of its capacity to improve muscle quality. Feeding faba beans improves the muscle quality of Yellow River carp. However, the changes in gut microbiota, along with the specific microorganisms, metabolic pathways, and regulatory mechanisms linked to the enhancement of muscle quality following faba bean consumption remain to be elucidated.</p><p>Results After a 6-week feeding trial with faba beans, growth performance decreased, but muscle texture improved (P < 0.05). Gut microbiota structure also changed, with increased relative abundances of Aeromonas, ZOR0006, Cetobacterium, and Atopobium. Following 8 weeks of whole-intestinal microbiota transplantation (WIMT) from faba bean-fed donors to basal diet-fed recipients of Yellow River carp, growth performance remained unchanged (P > 0.05), while muscle texture improved (P < 0.05). This improvement was mainly due to increased small-diameter muscle fibers, higher collagen levels, and reduced muscle fat content (P < 0.05), which partially replicated the muscle texture of donor fish. Moreover, WIMT promotes intestinal structure and barrier integrity, with significant changes in gut microbiota structure and metabolic profile. WIMT improved the muscle quality of Yellow River carp by regulating mitochondrial autophagy and adipocytokine signaling pathways through the gut-muscle axis. Cetobacterium somerae (C. somerae) and its metabolites, such as acetic acid, played a crucial role in this process. Further feeding experiments demonstrated that C. somerae and acetic acid reduced the crude fat content of muscle while increasing the crude protein and collagen (P < 0.05). C. somerae also mitigated muscle protein degradation under inflammatory and enhanced collagen (P < 0.05), thereby improving muscle texture.</p><p>Conclusion This study establishes that gut microbiota enhance muscle quality in Yellow River carp through WIMT, identifies C. somerae and its metabolite acetic acid as key contributors. The findings provide novel evidence for fish gut-muscle axis research and offer new scientific basis for improving Yellow River carp muscle quality.</p>
