English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

A preceding article (Lederberg, 1956a) was devoted to the evolution of protoplasts from growing cells of Escherichia coli treated with penicillin. Further studies have strengthened the correspondence of these protoplasts with the "large bodies" and "L forms" described for many other bacteria. This paper will give an account of these studies, and an interpretation of others, in support of the hypothesis that L forms are outgrowths of protoplasts. Their cell walls may be impaired either by extrinsic inhibition, for example, with penicillin, or by intrinsic metabolic defects, consequences of genetic mutations. The previous study was motivated mainly by the hope of furnishing protoplasts of genetically defined strains of E. coli for physiological and genetic analysis (Spiegelman, 1956; Spooner and Stocker, 1956). It was modeled on the experiments of Weibull (1953a) who forestalled the lysis of Bacillus megaterium exposed to lysozyme by maintaining the bacteria in a protective, hypertonic medium. It was found that the lysis of growing E. coli in the presence of penicillin could be forestalled in a medium containing M/3 sucrose and M/100 Mg; instead of lysing, the rods burgeoned out into osmotically fragile spheres, considered to be protoplasts. Similar effects of penicillin on growing bacteria have been described extensively from an altogether different viewpoint as an aspect of the development of L forms. For various reasons, species other than E. coli have been preferred for such studies. In general, the wall defects have been recognized but not stressed as the essential feature of L forms, and their relationship to protoplasts obtained with lysozyme has been

PROTOPLASTS AND L-TYPE GROWTH OF ESCHERICHIA COLI