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Characterization of the surface protein layers of the mosquito-pathogenic strains of Bacillus sphaericus
Abstract:
The protein surface layers on the cell walls of mosquito-pathogenic and nonpathogenic Bacillus sphaericus strains were studied by structural, biochemical, and serological methods. The surface structure of two representative insect-pathogenic strains had the form of a delicate linear array with a repeat interval of 5 nm. This was distinctly different from the tetragonal array of the P-1 strain in spacing and arrangement. The surface layers were composed of acidic glycoproteins with molecular weights ranging from approximately 133,000 to 155,000. Peptide mapping and serological analysis of the surface proteins revealed eight distinct groups among the pathogens. These groups were very similar to the groupings determined by flagellar-antigen serotyping and bacteriophage typing.
Insights
Bacillus sphaericus surface protein layers differ between pathogenic and nonpathogenic strains. These findings aid in classifying Bacillus sphaericus strains using their cell wall protein structures.
Area of Science:
- Microbiology
- Biochemistry
- Structural Biology
Background:
- Bacillus sphaericus is a bacterium with strains that can be pathogenic to mosquitoes.
- The cell wall surface layers of Bacillus sphaericus are proteinaceous and their structure is key to bacterial identification.
Purpose of the Study:
- To characterize the protein surface layers of mosquito-pathogenic and nonpathogenic Bacillus sphaericus strains.
- To compare the structural, biochemical, and serological properties of these surface layers.
Main Methods:
- Structural analysis using electron microscopy to determine array spacing and arrangement.
- Biochemical analysis including molecular weight determination and peptide mapping of surface glycoproteins.
- Serological analysis to compare surface protein groups with existing typing methods (flagellar-antigen and bacteriophage typing).
Main Results:
- Insect-pathogenic Bacillus sphaericus strains exhibited a delicate linear array (5 nm repeat interval) on their cell walls.
- This array structure was distinct from the tetragonal array found in nonpathogenic strains.
- Surface layers were identified as acidic glycoproteins (133,000–155,000 MW).
- Peptide mapping and serological analysis revealed eight distinct pathogenic groups, correlating with flagellar-antigen and bacteriophage typing.
Conclusions:
- The distinct surface protein layer structures in Bacillus sphaericus correlate with pathogenicity.
- Surface protein analysis provides a valuable method for classifying and differentiating Bacillus sphaericus strains.
- These findings contribute to understanding bacterial surface structures and their role in pathogenicity and identification.