Bacteroides the Good, the Bad, and the Nitty-Gritty

By a variety of measures, the species Homo sapiens is more microbial than human. Microorganisms comprise only a small, albeit significant, percentage of the body weight (between 2 and 5 pounds of live bacteria). However, in terms of cell numbers, we are about 10% human and 90% bacterial

the number of genes in our microbiome may exceed the number of human genes by two orders of magnitude making us genetically 1% human and 99% bacterial! Consequently, bacteria play a major role in bodily functions, including immunity, digestion, and protection against disease Colonization of the human body by microorganisms occurs at the very beginning of human life and many of these organisms become truly indigenous to the host.