Abstract
The buoyant density of whole cells of Streptococcus faecium varies with growth rate and during the cell cycle. Two possible explanations for this were explored: (i) the density of cell walls may vary, and (ii) the proportions of wall and cytoplasm may vary. We tested the first possibility by isolating walls from chilled, unfixed populations of S. faecium cells and fractionating them on Percoll density gradients. Mean cell wall density averaged 4% less than whole-cell density and did not vary significantly with growth rate. In addition, walls isolated from heavy and light fractions of a population of cells did not differ significantly in density. Thus, variation in the density of isolated cell walls could not account for the observed variation in whole-cell density within or between populations. Using previously published measurements of the physical dimensions of S. faecium cells, we also found that the relative proportions of wall and cytoplasm (see the second possibility above) could not account for the observed changes in whole-cell buoyant density.
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Selected References
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- Daneo-Moore L., Dicker D., Higgins M. L. Structure of the nucleoid in cells of Streptococcus faecalis. J Bacteriol. 1980 Feb;141(2):928–937. doi: 10.1128/jb.141.2.928-937.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dicker D. T., Higgins M. L. Cell cycle changes in the buoyant density of exponential-phase cells of Streptococcus faecium. J Bacteriol. 1987 Mar;169(3):1200–1204. doi: 10.1128/jb.169.3.1200-1204.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Edelstein E. M., Rosenzweig M. S., Daneo-Moore L., Higgins M. L. Unit cell hypothesis for Streptococcus faecalis. J Bacteriol. 1980 Jul;143(1):499–505. doi: 10.1128/jb.143.1.499-505.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Glaser D., Higgins M. Buoyant density, growth rate, and the cell cycle in Streptococcus faecium. J Bacteriol. 1989 Feb;171(2):669–673. doi: 10.1128/jb.171.2.669-673.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Higgins M. L., Shockman G. D. Study of cycle of cell wall assembly in Streptococcus faecalis by three-dimensional reconstructions of thin sections of cells. J Bacteriol. 1976 Sep;127(3):1346–1358. doi: 10.1128/jb.127.3.1346-1358.1976. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Koch A. L., Higgins M. L. Control of wall band splitting in Streptococcus faecalis. J Gen Microbiol. 1984 Apr;130(4):735–745. doi: 10.1099/00221287-130-4-735. [DOI] [PubMed] [Google Scholar]
- Marquis R. E. Immersion refractometry of isolated bacterial cell walls. J Bacteriol. 1973 Dec;116(3):1273–1279. doi: 10.1128/jb.116.3.1273-1279.1973. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ou L. T., Marquis R. E. Coccal cell-wall compactness and the swelling action of denaturants. Can J Microbiol. 1972 May;18(5):623–629. doi: 10.1139/m72-099. [DOI] [PubMed] [Google Scholar]
- Shockman G. D., Thompson J. S., Conover M. J. The autolytic enzyme system of Streptococcus faecalis. II. Partial characterization of the autolysin and its substrate. Biochemistry. 1967 Apr;6(4):1054–1065. doi: 10.1021/bi00856a014. [DOI] [PubMed] [Google Scholar]
- TOENNIES G., ISZARD L., ROGERS N. B., SHOCKMAN G. D. Cell multiplication studied with an electronic particle counter. J Bacteriol. 1961 Dec;82:857–866. doi: 10.1128/jb.82.6.857-866.1961. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tsien H. C., Shockman G. D., Higgins M. L. Structural arrangement of polymers within the wall of Streptococcus faecalis. J Bacteriol. 1978 Jan;133(1):372–386. doi: 10.1128/jb.133.1.372-386.1978. [DOI] [PMC free article] [PubMed] [Google Scholar]