microbial

Microbial is an adjective relating to microorganisms. Microorganisms include bacteria, archaea, fungi, algae, and protozoa, and, by some definitions, viruses and viroids. Microbes are among the oldest and most widespread forms of life, inhabiting nearly every environment on Earth, including soil, water, air, and the bodies of other organisms.

Most microbes are too small to see with the naked eye; bacteria and archaea range from about 0.2 to a few micrometers, while some protists are larger. Viruses, which infect cells, are even smaller and require host cells to reproduce. Microbes can exist as single cells or form colonies and biofilms.

Microorganisms drive essential ecological processes such as nutrient cycling, decomposition, and primary production. They participate in carbon, nitrogen, sulfur, and phosphorus cycles and influence the composition of communities in oceans, soils, and the human gut. In industry, microbes are used in fermentation, biotechnology, and bioremediation. In health, the gut microbiome and other resident microbial communities influence digestion, immunity, and metabolism; imbalances can be associated with disease.

Research on microbes employs culturing, microscopy, sequencing, and metagenomics. Advances have enabled diagnostics, vaccine and antibiotic development, and sustainable biotechnologies. Safety and ethics guide handling of microbial work, with biosafety levels and containment practices to prevent exposure or environmental release.

History notes: the discovery of microbes by Antoni van Leeuwenhoek using simple microscopes in the 17th century, and the subsequent development of germ theory by Louis Pasteur and Robert Koch, which established a causal link between microbes and disease.