Bacteria are a type of biological cell that represents a large domain of prokaryotic microorganisms. Bacteria were among the first life forms to exist on earth. They are habitually a few micrometers in length, and bacteria take on several forms and shapes. These include spirals, spheres, and rods. Almost all animals on earth are reliant on bacteria for their survival.
Only bacteria and some archaea have the enzymes and genes required to synthesize vitamin B-12 and deliver it through the food chain. Bacteria can be hazardous such as when they cause infection or helpful, as in the process of fermentation. Bacteria can be observed ubiquitously in the environment, such as soil, water, and air.
Bacteria are a single-celled microscopic organism. They can be found everywhere. Bacteria can be beneficial, and some can be harmful. Bacteria are categorized as prokaryotic organisms because they lack a nucleus. Bacteria can be found in the soil, animals, plants, waste, and deep in the earth’s crust. Bacteria have three basic shapes — spherical, spiral, and rod shape. Spherical bacteria are ball-like, and they are known as “cocci.” An example of cocci is streptococcus that causes sore throat. Spiral bacteria are bacteria that are spiral in shape.
They are known as “spirilla.” Examples are leptospirosis; Rod-shaped bacteria are known as bacilli. A common example is Bacillus anthrax. Bacteria are also classified based on how they interact with oxygen. Bacteria that require oxygen to grow are known as aerobic bacteria, and those that can survive with oxygen are called anaerobic bacteria. Some bacteria can live with or without oxygen; these groups of bacteria are known as facultative aerobic or anaerobic bacteria.