Open AccessUltrastructure of the cell envelope and amino acid composition of the murein of Clostridium symbiosum
Author(s) -
König Helmut,
Buckel Wolfgang,
Langworthy Thomas A.
Publication year - 1985
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1985.tb01097.x
Subject(s) - peptidoglycan , cell envelope , clostridium , endospore , s layer , biology , ultrastructure , biochemistry , cell wall , bacteria , negative stain , gram negative bacteria , bacterial cell structure , bacterial outer membrane , microbiology and biotechnology , biophysics , electron microscope , spore , anatomy , escherichia coli , genetics , physics , optics , gene
The cell envelope of the Gram‐negative staining Clostridium symbiosum is 18 nm thick. It appears triple‐layered and consists of an inner electrondense layer of about 5 nm, a lighter zone of 4 nm and an outer electron‐dense layer of 9 nm. The inner layer corresponds to the murein sacculus, since the isolated peptidoglycan sacculi showed a thickness of 3–5 nm. Analysis showed that it belongs to the A 2 pm‐direct murein type. The outer layer could be removed by sodium dodecylsulfate. It contained mainly protein, small amounts of sugars and essentially no lipid, indicative of an S‐layer rather than a typical Gram‐negative type of outer membrane. Furthermore, l ‐alanine aminopeptidase activity characteristic of Gram‐negative aerobic bacteria was absent in this organism and in other anaerobic Gram‐negative bacteria tested. This demonstrates that such activity is an unreliable tool for the classification of anaerobic eubacteria. In spite of the thin murein layer, which is the likely reason for the Gram‐negative reaction, the anaerobic growth, peritrichous flagellation and endospore formation indicate that this organism belongs to the genus Clostridium .