Microbiotas

Microbiotas are the communities of microorganisms that inhabit a defined environment, from the human gut and skin to soil, oceans, and other habitats. They include bacteria, archaea, fungi, viruses, and protozoa that interact with each other and with their host or surroundings. The term emphasizes the ecological community rather than the genetic material alone.

Composition varies by habitat and individual. Some taxa form a core microbiota, while a long tail of rare species adds resilience and adaptability. The makeup is influenced by factors such as genetics, age, diet, lifestyle, antibiotics, climate, and exposure to other organisms.

Functions depend on the habitat but commonly include nutrient metabolism, immune modulation, protection against pathogens, synthesis of vitamins, and involvement in biogeochemical cycles in ecosystems. In humans, gut microbiotas ferment complex carbohydrates to short-chain fatty acids and shape immune development; skin and oral microbiotas contribute to barrier defense and oral health.

Development is dynamic. Early colonization after birth is shaped by delivery mode and feeding, with microbiotas stabilizing across childhood and changing with aging, illness, and treatments. Methods to study microbiotas rely on sequencing and -omics approaches, such as 16S rRNA profiling, metagenomics, metatranscriptomics, and metabolomics, each with limitations.

Applications include dietary interventions, probiotics and prebiotics, and fecal microbiota transplantation in some contexts. Microbiotas are a major component of ecosystem function and health, and research emphasizes careful interpretation of associations, variability among individuals, and the ecological complexity of microbial communities.