Properties of Bacillus cereus temperature-sensitive mutants altered in spore coat formation

Abstract

Three conditional Bacillus cereus mutants altered in the assembly or formation of spore coat layers were analyzed. They all grew as well as the wild type in an enriched or minimal medium but produced lysozyme and octanol-sensitive spores at the nonpermissive temperature (35 to 38°C). The spores also germinated slowly when produced at 350C. Temperature-shift experiments indicated that the defective protein or regulatory signal is expressed at the time of formation of the outer spore coat layers. Revertants regained all wild-type spore properties at frequencies consistent with initial point mutations. Spore coat defects were evident in thin sections and freeze-etch micrographs of mutant spores produced at 350C. In addition, one mutant contained an extra surface deposit, perhaps unprocessed spore coat precursor protein. A prevalent band of about 65,000 daltons (the same size as the presumptive precursor) was present in spore coat extracts of this mutant and may be incorrectly processed to mature spore coat polypeptides. Another class of mutants was defective in the late uptake of half-cystine residues into spore coats. Such a defect could lead to improper formation of the outer spore coat layers.

Toxicity of local Malaysian Bacillus thuringiensis subspecies Kurstaki against Plutella xylostella

“…Wilson and Benoit (1993) and Benoit et al (1995) reported similar observation on the effect of LAA on Btk germination. While many findings reported that coatless spores have decreased rate of germination (Nakatani et al, 1985a;1985b -Bacillus megaterium) or at a rate that comparable to coated spores (Stelma et al, 1978;Kutima and Foegeding, 1987 -Bacillus cereus), the current study showed opposite trend, where rate of germination was increased by removal of spore coat. These results made the influence of coat on germination remain unclear however it may be related to species.…”

Involvement of the spore coat in germination of Bacillus cereus T spores

“…Such spores can be germinated artificially by addition of cortex-lytic enzymes, such as lysozyme, or spore-specific enzymes (1,4,27). Coatless spores have been observed to germinate at a decreased rate (13,17,18,28), and in somne cases mutants lacking spore coats germinate at a rate comparable to normal spores (26). The exact involvement of the coat and outer membrane in germination is unclear.…”

Precursor processing during the maturation of a spore-coat protein in Bacillus megaterium KM.

“…A number of previous reports have suggested that spore-coat proteins may be synthesized as highmolecular-weight precursors, which are proteolytically cleaved to produce smaller mature proteins (Cheng & Aronson, 1977;Aronson & Pandey, 1978;Munoz et al, 1978a,b;Stelma et al, 1978;Pandey & Aronson, 1979;Aronson, 1981;Goldman & Tipper, 1981). These precursors can be identified immunologically in both Bacillus cereus and Bacillus subtilis as proteins ranging from mol.wt.…”