This study explores how different gut bacteria and their metabolic functions influence skin transplant outcomes and immune responses. Previous research showed that antibiotics could delay organ rejection and lessen immune reactions. In this study, specific antibiotic combinations were used to target key bacterial groups in mice, revealing that targeting all major gut bacterial groups simultaneously most effectively extended skin transplant survival and reduced immune responses. The research identified a common gut bacterium, Parabacteroides distasonis, enriched after antibiotic treatment. Giving mice P. distasonis extended the life of skin transplants, suggesting its potential as a probiotic therapy in transplantation. This work highlights the additive effect of gut microbial diversity on immune responses and introduces a novel approach to improving transplant outcomes through microbiota modulation. The significance lies in identifying a specific gut bacterium with therapeutic benefits for transplantation, offering a new avenue for enhancing transplant success.