Microbially-derived essential amino acids compensate for dietary deficiencies in deer mice (Peromyscus) 9294

Abstract Description Wild mammalian herbivores and omnivores often consume diets deficient in the amount of protein required for growth, reproduction, and proper immune function. To compensate, mammals likely rely on their gut microbiota to synthesize essential amino acids (AAESS) needed for survival. We quantified the contribution of microbially synthesized AAESS to the skeletal muscle of deer mice (Peromyscus maniculatus) fed diets differing in protein quantity and quality, including a synthetic diet rich in simple sugars and highly digestible protein (casein), and a semi-natural diet containing complex carbohydrates and natural protein (cricket powder) that better mimic what mice consume in the wild. We combined -omics with compound-specific stable isotope (δ13C) analysis to trace the origin of AAESS used by mice to build skeletal muscle. We found that diet type plays a substantial role in host assimilation of microbially derived AAESS. Mice fed low protein diets had greater contributions of microbially derived AAESS in their skeletal muscle and more abundant gut microbial populations with the genetic potential for AAESS biosynthesis. These results reveal the crucial and likely pervasive role the gut microbiome plays in host protein metabolism, especially in wild mammals facing dietary protein limitation. Our study highlights one mechanism microbes exchange essential nutrients with their host, however, the impact of these exchanges on host immunity and overall health remains to be explored. Funding Sources Supported by NSF 1755402; 1755353; NSF/GRFP 2439853 Topic Categories Mucosal and Regional Immunology (MUC)