Bacteria, Forms of

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Bacteria, Forms of


the external shapes of bacterial cells. The most common forms of bacteria are spherical (cocci), rod-shaped (bacilli), and spiral-shaped (vibrios and spirilla).

A distinct type of bacterium, called an L form, or L variant, is produced when a bacterium’s cell wall is partly or almost destroyed, or when the cell loses its ability to form a wall. Unlike spheroplasts and protoplasts, L forms retain their ability to grow and reproduce. They were discovered in 1935 by the English biologist E. Klieneberger-Nobel and were named L (Listeria) forms after the Lister Institute of Preventive Medicine in London. L transformation can occur in most species of bacteria, including cocci, Escherichia coli, and Pasteurella.

L forms of different species of bacteria may be identical morphologically; they are generally spherical, vacuolated bodies varying in size from 1 micron to 250 nanometers. L forms are produced under the influence of such substances as penicillins, which prevent the biosynthesis of the bacterium’s cell wall. L forms are also produced when bacterial cell division is inhibited while cell growth is maintained. Under certain conditions, L forms can revert to the original bacteria. L forms often occur during the course of such prolonged diseases as brucellosis.


Timakov, V. D., and G. Ia. Kagan. Semeistvo Mycoplasmataceae i L-formy bakterii. Moscow, 1967.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.