A temperature sensitive mutant of bacillus subtilis: Analysis of physiological spore defects

A temperature sensitive sporulation mutant of Bacillus subtilis was isolated and its chemical and physical characteristics were investigated. This mutant is able to grow equally well at 30° and 42°C, but is unable to produce a normal healthy spore at the restrictive temperature of 42°C. Properties of the spore such as heat resistance, refractility, and resistance to osmotic shock were normal in the parent strain but were altered in the mutant at the restrictive temperature. Calcium levels were found to be lower in the mutant than in the normal strain. One plausible hypothesis which would explain all of these observations is that the spore cortex , which is the site of the murein–Ca: DPA complex, ma be improperly crosslinked and thus exhibit the altered phenotypic characteristics of the mutant spore.