Question

How have human activities influenced the composition of our internal microbiota? What activities drive these effects? Outline some potential consequences of changes to our microbiota.

Please give a detailed answer. Add supportive equations or flow diagrams if possible.

Thank you.

Answer 1

Plants, animals and humans, are colonized by microorganisms (microbiota) and transiently exposed to countless others. The microbiota affects the development and function of essentially all organ systems, and contributes to adaptation and evolution, while protecting against pathogenic microorganisms and toxins.

Human activities that influence composition of microbiota:

• Genetics and lifestyle factors, including diet, antibiotics and other drugs, and exposure to the natural environment, affect the composition of the microbiota, which influences host health through modulation of interrelated physiological systems.
• These include immune system development and regulation, metabolic and endocrine pathways, brain function and epigenetic modification of the genome. Importantly, parental microbiotas have transgenerational impacts on the health of progeny.

Microbiota and effect of antibiotics:

• In addition to food, any absorbed substances, including pharmaceutical products such as metformin used to treat type 2 diabetes, have an obvious impact on gut microbiota.
• Antibiotics not only reach pathogenic bacteria but also impact our beneficial microbiota, leading to perturbation of its composition and biodiversity, and often to an increase in Proteobacteria because of the high content of antimicrobial resistance genes in this phylum.
• The disruption of our microbiota caused by antibiotics favors the development of NCDs characteristic of dysbiosis .The risk of obesity, atopic disease, asthma, Crohn's disease, type 2 diabetes, auto-immune diseases (like type 1 diabetes) have been shown, in human epidemiological studies, to be positively correlated with antibiotic use, particularly if absorbed during early life.
• The microbiota of infants who were not treated by antibiotics but whose mothers received antibiotics before delivery showed the same alterations as infants treated by antibiotics, with consequences in later life.
• As a consequence of the substantial loss of gut microbiota biodiversity caused by antibiotics, susceptibility to opportunistic pathogenic infections can increase. This is confirmed in antibiotic-associated diarrheas due to nosocomial pathogens, like Staphylococcus aureus and Clostridium difficile inducing potentially lethal colitis.
• Risk of sepsis has also been related in premature infants to the length of treatment with broad spectrum antibiotics and the consequent altered gut microbiota.

Please find out the following flow diagram.