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The autolytic phenotype of Bacillus thuringiensis
1Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi, Milano, Italy.
Journal of Applied Microbiology
|June 10, 2004
Summary
The autolytic phenotype of Bacillus thuringiensis varies by strain and is influenced by pH. This research reveals key peptidoglycan hydrolases active at alkaline pH, with potential for biocontrol applications.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Bacillus thuringiensis is a bacterium with significant potential in biocontrol.
- Understanding its autolytic properties is crucial for optimizing its applications.
Purpose of the Study:
- To characterize the autolytic phenotype of various Bacillus thuringiensis strains.
- To identify the peptidoglycan hydrolases responsible for autolysis and their activity patterns.
Main Methods:
- Assessed autolytic rates of 87 B. thuringiensis strains across different pH levels (6, 6.5, 8.5) under starvation.
- Evaluated peptidoglycan hydrolase activity using renaturing SDS-PAGE with indicator bacteria.
- Tested the effect of various salts and pH on enzyme activity.
Main Results:
- Autolysis was strain-dependent at pH 6 but more uniform at pH 6.5 and 8.5.
- Identified seven major peptidoglycan hydrolase bands (90-25 kDa), with a prominent 25 kDa band at 72h.
- Lytic activity was retained against Micrococcus lysodeicticus and Listeria monocytogenes, increasing at alkaline pH and inhibited by NaCl.
Conclusions:
- Bacillus thuringiensis exhibits a strain-dependent autolytic phenotype with diverse peptidoglycan hydrolases.
- These hydrolases show enhanced activity at alkaline pH and can lyse other bacterial species.
- Characterizing autolysis may enhance the use of B. thuringiensis in biocontrol and field applications.