Dynamics of Microbiomes

Microbiomes are dynamic, changing as a function of numerous internal and environmental factors. Age, gender, diet, physical activity, stress, temperature, medicines, disease, and bacteriophage all contribute to short- and long-term changes in microbiomes. In most cases, it is not known if the changes are only quantitative (only amounts) or qualitative (loss or gain of microbes). In addition to the gut microbiota, skin and mouth also show reproducible associations between microbiota and chronological age. The concept that microbial diversity can play a critical role under conditions of fluctuating environments has been referred to as the insurance policy hypothesis. There is a considerable individual variation on how diet and other factors affect the microbiome. Diet has a major effect on the microbial compositions of the human gut microbiome. Humans not only feed themselves but also feed their gut microbiota. Food, food additives, and essentially any material that is put in the mouth affects the gut microbiome at all ages. Diet not only affects the microbiome during pregnancy, but also influences the gut microbiome of the offspring. Many diseases are correlated with changes in the microbiome. However, it is not clear if the microbes are responsible for the disease, or the disease is responsible for the change in the microbiome. Another important factor that contributes to the dynamics of microbiomes is the interaction between bacteriophage and bacteria. The dynamic properties of microbiomes assist in adaptation to changing environments.