Microbiota

Abstract

This chapter brings in concepts from macroecology regarding diversity and trophic levels. Microbial diversity or richness could appear higher in some diseased conditions, especially when going beyond the gut microbiome. Single species dominance in the vaginal microbiome becomes more diverse in the majority of postmenopausal women, as the pH is no longer maintained as acidic. Nutrients and selective forces for in situ communities such as the skin and the oral microbiomes are briefly covered. Mucins, immunoglobulins, or even glycans expressed as blood group antigens, help microbes with localization and food. For the gut microbiome, the primary bioreactor is the ascending colon, while the microbes might spread out along the length of the colon, fermenting what they can ferment. Human genetics, historical contingency, and circadian rhythms all contribute to what we currently see in the microbiome, together with more studied factors such as nutrients and immune responses. Trophic levels in a human microbiome site may need to consider different scenarios of physiological states, during which different molecules are available, and different functions may be evolutionarily prioritized.