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Isolation and characterization of outermost layer deficient mutant spores of Bacillus megaterium
Y Takubo1, M Atarashi, T Nishihara
1Department of Environmental Chemistry and Microbiology, Faculty of Pharmaceutical Sciences, Osaka University.
Abstract:
Outermost layer deficient mutant spores of Bacillus megaterium ATCC 12872 were isolated by Urografin density gradient centrifugation after mutagenesis with ethyl methanesulfonate. Although the composition of the cortex peptidoglycan was the same as that of the parent spores, three major proteins (48, 36, and 22 K daltons) were missing, suggesting that these proteins are components of the outermost layer. All mutant spores were also found to have very hydrophobic surface by 'salt aggregation test,' which would facilitate selection of such mutants.
Insights
Mutant Bacillus megaterium spores lacking an outermost layer were identified. Missing proteins suggest their role in spore surface hydrophobicity and layer formation.
Area of Science:
- Microbiology
- Bacterial spore research
- Protein biochemistry
Background:
- Bacillus megaterium spores possess a complex multilayered structure crucial for survival.
- The outermost layer's composition and function remain incompletely understood.
- Identifying specific protein components is key to elucidating spore coat assembly and properties.
Purpose of the Study:
- To isolate and characterize Bacillus megaterium mutants deficient in the outermost spore layer.
- To identify the specific proteins absent in these mutant spores.
- To investigate the relationship between the outermost layer and spore surface hydrophobicity.
Main Methods:
- Bacterial mutagenesis using ethyl methanesulfonate.
- Isolation of mutant spores via Urografin density gradient centrifugation.
- Analysis of cortex peptidoglycan composition.
- Protein identification using molecular weight (K daltons).
- Assessment of surface hydrophobicity using the salt aggregation test.
Main Results:
- Successfully isolated Bacillus megaterium mutants lacking the outermost spore layer.
- Mutant spores showed the same cortex peptidoglycan composition as wild-type.
- Three major proteins (48, 36, and 22 K daltons) were absent in the mutant spores.
- Mutant spores exhibited significantly increased surface hydrophobicity compared to parent spores.
Conclusions:
- The identified 48, 36, and 22 K dalton proteins are likely essential components of the Bacillus megaterium spore outermost layer.
- The outermost layer significantly contributes to the spore's surface hydrophobicity.
- The salt aggregation test is a viable method for selecting mutants with altered surface properties.