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Optimization of mosquitocidal toxin synthesis from Bacillus sphaericus using gene fusions
H K Ahmed1, W J Mitchell, F G Priest
1Department of Biological Sciences, Heriot Watt University, EH 14 4AS, Edinburgh, UK.
World Journal of Microbiology & Biotechnology
|January 14, 2014
Summary
Reporter gene fusions in Bacillus sphaericus track mosquito-larvicidal toxin expression. Optimal fermentation conditions enhance gene expression and toxicity, but bioassays are needed for confirmation.
Area of Science:
- Microbiology
- Molecular Biology
- Biotechnology
Background:
- Bacillus sphaericus produces toxins lethal to mosquito larvae.
- Monitoring toxin gene expression is crucial for optimizing production.
Purpose of the Study:
- To evaluate beta-galactosidase gene fusions as reporters for mosquito-larvicidal toxin gene expression in Bacillus sphaericus.
- To correlate reporter gene expression with larvicidal toxicity under various fermentation conditions.
Main Methods:
- Utilized beta-galactosidase gene fusions to monitor toxin gene expression in Bacillus sphaericus strain 2362.
- Compared beta-galactosidase activity with larvicidal toxicity in late-growth-phase batch cultures.
- Investigated the impact of fermentation conditions (trace elements, protein sources, acetate) on gene expression and toxicity.
Main Results:
- Conditions promoting sporulation, like trace elements and crude protein, enhanced reporter gene expression and larvicidal toxicity.
- Acetate repressed sporulation, leading to reduced binary toxin yield.
- A poor correlation between reporter gene expression and toxicity was observed at high toxicity levels.
Conclusions:
- Beta-galactosidase gene fusions can aid in rapidly screening fermentation conditions for Bacillus sphaericus larvicidal toxin production.
- Bioassays are essential to confirm results from reporter gene experiments, especially at high toxicity levels.
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