microbial biomass microbial biomass composed of microorganisms microbial biomass scientists are beginning to discover per a 2007 study Human Microbiota http://mpkb.org/home/pathogenesis/microbiota http://mpkb.org/home/pathogenesis/microbiota 100 trillion bacteria 100 trillion bacteria composed of microorganisms per a 2007 study composed of microorganisms microbial biomass