The human microbiota is the aggregate of microorganisms, a microbiome that resides on the surface and in deep layers of skin (including in mammary glands), in the saliva and oral mucosa, in the conjunctiva, and in the gastrointestinal tracts.They include bacteria, fungi, and archaea.lthough cancer is generally a disease of host genetics and environmental factors, microorganisms are implicated in ~20% of human malignancies. Mucosal microbes can become part of the tumor microenvironment (TME) of aerodigestive tract malignancies.