bacterias

Bacteria are a large domain of unicellular, prokaryotic microorganisms. They lack a membrane-bound nucleus and most have a cell wall made of peptidoglycan. Bacteria occur in a remarkable range of sizes and shapes, including spheres (cocci), rods (bacilli), and spirals. Most bacteria reproduce by binary fission, a rapid, asexual process, though genetic exchange can occur through transformation, transduction, or conjugation.

Bacteria inhabit nearly every environment on Earth, from soil and water to the guts of animals. They display a wide diversity of metabolic strategies, including photosynthesis in cyanobacteria, oxidation of inorganic compounds, and heterotrophic metabolism. Their activities influence nutrient cycles, decomposition, and the availability of minerals in ecosystems.

Bacteria play crucial roles in human health and industry. The gut microbiota aids digestion and immune function; many bacteria ferment foods and produce vitamins. Some species are beneficial in biotechnology, producing enzymes, antibiotics, and biofuels. Others are pathogenic, causing diseases such as tuberculosis, cholera, and bacterial infections that threaten crops or animals. Pathogenicity often involves toxins, adherence to tissues, and evasion of host defenses.

In laboratories, bacteria are studied under controlled conditions using culture methods, microscopy, and genetic analysis. Gram staining distinguishes two major cell wall types, guiding treatment choices in medicine. The study of bacteria has a long history, beginning with early microscopes, formalized by Koch’s postulates and advances in microbiology.

Bacteria are classified alongside archaea and eukaryotes based on genetic and biochemical criteria. They remain a central subject in biology due to their ubiquity, diversity, and impact on health, ecology, and industry.