Microbial community proteomics for characterizing the range of metabolic functions and activities of human gut microbiota
We found that the human gastrointestinal (GI) tract is a complex, dynamic ecosystem that consists of a carefully tuned balance of human host and microbiota membership. The microbiome component is not insignificant, but rather provides important functions that are absolutely critical to many aspects of human health, including nutrient transformation and absorption, drug metabolism, pathogen defense, and immune system development. Microbial community proteomics (sometimes referred to as metaproteomics) provides a powerful approach to measure the range and details of human gut microbiota functions and metabolic activities, revealing information about microbiome development and stability especially with regard to human health vs. disease states. In most cases, both microbial and human proteins are extracted from fecal samples and then measured by the high performance MS-based proteomics technology. We review the field of human gut microbiome community proteomics, with a focus on the experimental and informatics considerations involved in characterizing systems that range from low complexity defined model gut microbiota in gnotobiotic mice, to the simple gut microbiota in the GI tract of newborn infants, and finally to the complex gut microbiota in adults. Moreover, the current state-of-the-art in experimental and bioinformatics capabilities for community proteomics enable a detailed measurement of the gut microbiota, yielding valuable insights into the broad functional profiles of even complex microbiota. Future developments are likely to expand into improved analysis throughput and coverage depth, as well as post-translational modification characterizations.