How many types of bacteria are there?

Currently, estimates of the complete number of species range from ten million to a billion. These estimates are generalized and might not be exact, as it would be impossible to pin down a specific number of bacteria, even with our modern technology. By comparison, there are probably between ten and thirty million species of animals.

The most prevalent of which are insects. To have a fair number, people would need a machine that could process water, rock, and soil in sizable amounts, isolate the bacteria from the habitat, then the series of the genomes of as many bacteria as feasible within the sample.

Bacteria are classified into five main groups. These groups are: cocci, bacilli, spirochetes, Rickettsia and mycoplasma Cocci: are round-shaped bacteria that occur in chains, pairs, or clusters. Cocci bacteria are further categorized into gram-positive or gram-negative cocci based on their response to gram stain. Examples of cocci are Staphylococcus aureus, Streptococcus pyogenes, and Neisseria meningitides. Bacilli: are rod-shaped bacteria. They occur singly or linked together in chains.

They are also classified into gram-positive or negative bacilli. Examples are Corynebacterium diphtheria, E. coli. Spirochetes are long, corkscrew-shaped bacteria. Common examples are Treponema pallidum and Borrelia burgdorferi. Rickettsia: this family of bacteria can only survive in another living cell. Mycoplasma: unlike other bacteria, this single bacterium lacks a cell wall. It is known to cause pneumonia.