Overproduction of Delta-Endotoxins by Sporeless Bacillus thuringiensis Mutants Obtained by Nitrous Acid Mutagenesis
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Asporogenic and oligosporogenic Bacillus thuringiensis mutants having the ability to overproduce insecticidal crystal protein were generated by using nitrous acid (50 mg/ml), as chemical mutagenic agent. Insecticidal crystal proteins produced by asporogenic mutants remained encapsulated within the cells. Delta-endotoxin production by most of mutants was improved compared to the corresponding wild strains BNS3 and a mutant M26. The overproduction by asporogenic and oligosporogenic mutants was attributed to defect in genes involved in sporulation and to random mutations affecting cell metabolism at different pathways and delta-endotoxin synthesis. Sporeless bioinsecticides could be developed based on stable and environmentally safe Bacillus thuringiensis mutants.
KeywordsShake Flask Complex Medium Glucose Medium Random Mutagenesis Duncan Test
This work was supported by grants from the “Tunisian Ministry of Higher Education, Scientific Research and Technology” and the AUF “Agence Universitaire de la Francophonie”. We wish to thank Pr. Mohamed Ben Khedher and Dr. Moez Feki, for having proofread this paper.
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