An analysis of the outer membrane proteins of Enterobacter aerogenes exopolysaccharide producing and non-producing strains was made. Growth of these strains under nutrient limitation or in the presence of membrane active agents altered the ratios of proteins in the outer membrane and the yield of exopolysaccharide. The latter compounds had a substantial effect particularly on the major outer membrane proteins. The cytoplasmic membrane proteins of different strains varied slightly in quantity, unrelated to exopolysaccharide synthesis. Lipopolysaccharide extracted from a number of strains was examined by polyacrylamide gel electrophoresis. Differences were detected between strains but this did not correlate with exopolysaccharide yield or form. The major outer membrane proteins were identified as 34K and 38K polypeptides by SDS-polyacrylamide gel electrophoresis. These proteins exhibited the normal properties associated with the major non-porin and porin proteins of E coli. The former protein was cleaved by 'Pronase' in situ and was heat-modifiable in SDS-containing gel sample buffer. The latter was peptidoglycan associated. Several polypeptides were induced by iron limitation and the citrate-ferric ion receptor protein of the Enterobacter aerogenes strains tested appeared to correspond to an 86K polypeptide. Growth in the presence of chaotropic agents resulted in a significant decrease in the 38K protein and an increase in a polypeptide in the 29K-32K range. Other changes in minor proteins may also have occurred. Two polypeptides, 50K and 58K were apparently associated with encapsulation and slime-formation respectively. A role in exopolysaccharide production was postulated.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649005 |
| Date | January 1982 |
| Creators | Cumming, Gordon Daniel |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13517 |
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