The purpose of this investigation was to compare some of the
properties of a spore-forming mutant of Bacillus cereus 569R with
the wild type. The strains were grown under identical conditions in
liquid medium. The mutant, strain 45, was characterized with
respect to growth rate, pH changes in the medium, morphological
development, cell density during the growth cycle, the effect of
oxygen deprivation on the time of spore formation, and the production
of an extracellular protease.
Strain 45 was found to maintain a higher growth rate than 569R.
The pH curves indicated that, in time, strain 45 was about 30 minutes
ahead of wild type. Morphologically, strain 45 exhibited no long chain
stage characteristic of early logarithmic growth B. cereus 569R.
Poly β hydroxybutyrate was accumulated before the sharp rise in pH
in 45. This comparatively early synthesis suggested that acetate
utilization and polymer synthesis may not be coordinately controlled
in this mutant. Spore formation occurred two and one-half hours
earlier in strain 45, and the spores were twice as large as spores of
wild type. The production of protease in the mutant occurred earlier,
and in higher concentration when compared with 569R.
The results of these experiments fell into two classes. The
first class included growth rate, pH, and cell density shifts. These
events occurred approximately one-half hour earlier in cultures of
strain 45, and appeared to be correlated with the cell mass. The
second class of results--the time of polymer synthesis, the period
when the time of sporulation was sensitive to oxygen, the time of
protease production, and the time of sporulation- - appeared to be
independent of cell mass, and occurred markedly earlier in strain
45. The very early appearance of these sporulation- related events
in the culture cycle suggested that the mutant strain 45 may be
catabolically derepressed for sporulation. Characterization of two
asporogenous mutants of B. cereus 569R was also undertaken. / Graduation date: 1970
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29629 |
| Date | 18 December 1969 |
| Creators | Brantner, Carol Jeanne |
| Contributors | Fraser, Dorothy K. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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