Bakteria

Bakteria, more commonly referred to as bacteria, constitute a large domain of prokaryotic microorganisms that are found in virtually all habitats on Earth, ranging from soil and water to the human body. They are single‑celled organisms lacking a membrane‑bound nucleus and most organelles, with genetic material typically organized in a circular chromosome. Many bacteria also possess extrachromosomal DNA elements called plasmids, which can carry genes for antibiotic resistance or metabolic functions.

Bacterial cells vary widely in size, shape, and metabolic capability. Common morphologies include cocci (spherical), bacilli (rod‑shaped), and spirilla (helical). They reproduce primarily by binary fission, a rapid asexual process that can generate populations of millions within hours under favorable conditions. Some species form endospores, highly resistant structures that enable survival during extreme stress.

Ecologically, bacteria play essential roles in nutrient cycling, such as nitrogen fixation, decomposition of organic matter, and digestion in the guts of animals. In medicine, bacteria are recognized both as pathogens responsible for diseases like tuberculosis, cholera, and bacterial meningitis, and as beneficial agents employed in biotechnology, including the production of insulin, antibiotics, and enzymes for industrial processes.

The study of bacteria, bacteriology, employs techniques ranging from classical culture methods to modern molecular genetics and metagenomic sequencing. These approaches have expanded understanding of bacterial diversity, evolutionary relationships, and mechanisms of pathogenicity. Public health strategies focus on preventing bacterial infections through vaccination, hygiene, and prudent use of antibiotics to mitigate the spread of resistant strains.