mikrobe

Mikrobe, short for microbe, is a microscopic organism. In common usage the term covers bacteria, archaea, fungi, protozoa, and algae, and, in many contexts, viruses. Microbes are found almost everywhere: in soil, oceans, air, surface waters, and within and on living organisms. They range from unicellular to simple multicellular forms and are often invisible to the naked eye.

Most microbes are unicellular organisms or simple colonies. Bacteria and archaea are prokaryotes, lacking a defined nucleus; fungi, protozoa, and algae are eukaryotes. Size varies widely: bacteria and archaea typically 0.5–5 micrometers, viruses about 20–300 nanometers, and larger fungal cells and protozoa can be visible under a light microscope. Metabolism is diverse: some phototrophic microbes fix light energy, others decompose organic matter, and many have specialized interactions with hosts or environments. While some microbes cause disease, many are harmless or beneficial.

Ecologically, microbes drive nutrient cycling, decomposition, and primary production. The human body hosts complex microbial communities (the microbiome) that aid digestion, protect against pathogens, and influence development and immune function. Microbes have wide use in biotechnology and medicine: production of antibiotics, enzymes, fermented foods, and recombinant proteins; model organisms such as Escherichia coli and Saccharomyces cerevisiae help scientists study basic biology.

Scientists study microbes using culture techniques, microscopy, molecular methods (such as DNA sequencing and PCR), and metagenomics. Because many microbes cannot be grown in the laboratory, culture-independent approaches are essential for understanding environmental and clinical samples. The history of microbiology includes the discovery of microbes by early microscopes, the germ theory of disease, and the development of antimicrobial therapies and vaccination.