Question

Discuss the various forms of bacteria.

Answer 1

The bacteria are most commonly classified on the basis of their morphology, that is shape and appearance. The three basic shapes of bacteria are spherical, rod shaped and spiral. On the basis of this, there are five forms of bacteria.

(i) Coccus: These are round shaped bacteria. They are either single or occur in pairs, chain or clusters. For example, Staphylococcus aureus occurs in cluster of cocci.

(ii) Bacillus: These are rod shaped bacteria. They are either single or occur in linked chains. Corynebacterium diphtheriae is an example of bacillus.

Spiral-shaped bacteria are further divided into 3 groups depending on how much spiraling they show.

(iii) Vibrio: They have spiral or comma shape. They are mostly found in aquatic environment. Vibrio cholerae is an example of vibrio bacteria.

(iv) Spirillum: They have rigid, corkscrew-like spiral shape. Campylobacter jejuni is an example of spirillum bacteria.

(v) Spirochete: These are flexible, thin, crokscrew-like spiral shaped bacteria. They move in a typical rotating manner. Treponema pallidum is an example of spirochete bacteria.