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Background <p>To develop a new generation of eco-friendly biopesticides, this study used an optimized random mutagenesis approach to generates oligosporogenic mutants from <i>B. thuringiensis</i> var. <i>kurstaki</i> BLB1. Although random mutagenesis is not a novel approach, it remains a practical and efficient strategy providing a simple and accessible alternative.</p> Results <p>Screening of over than 600 mutants showed that only 14 clones harbour less rate of spores ranging from 1 ± 0.5 10<sup>–6</sup> to 126 ± 1 10<sup>–6</sup> spores ml<sup>−1</sup>. Among them, a number of 6 mutants showed an improvement of delta-endotoxins until 222.92%. Protease production showed that S6 mutant exhibited the most increased rate of about 4136.36 U ml<sup>−1</sup> ± 89.65 in addition to its enhancement of 34,96% in delta-endotoxins production. Captively, S3 and S4 mutants were largely active against <i>A. tumefaciens</i> and three fungi revealing values of MIC and MFC ranging from 0.07 to 0.31&#xa0;µg&#xa0;ml<sup>−1</sup> and from 0.05 to 0.225&#xa0;µg&#xa0;ml<sup>−1</sup> against <i>A. niger</i>, <i>F. culmorum</i> and <i>B. cinerea</i>, respectively. Oligosporogenic S6 mutant was considered as a polyvalent and eco-friendly biopesticide since it is the most toxic against semolina larvae <i>E. kuehniella</i> (LC<sub>50</sub> of 39.52&#xa0;µg&#xa0;g<sup>−1</sup>). To reduce its production cost, we explored the use of date waste as a cost-effective culture medium. An improvement of 43.15% of delta-endotoxins production of S6 mutant was obtained via Taguchi design while valorising agricultural by-products.</p> Conclusion <p>The study successfully generated oligosporogenic mutants of <i>B. thuringiensis</i> BLB1 with enhanced delta-endotoxin and enzyme production while reducing spore formation. The S6 mutant showed the highest bioactivity, and its production was further increased in a cost-effective way using date waste as a culture medium, highlighting its potential as a useful and eco-friendly biopesticide.</p>

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Isolation and production of newly oligosporogenic polyvalent Bacillus thuringiensis mutants for agricultural pest control

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月20日

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  • Sameh Sellami,
  • Fatma El Abed,
  • Zayneb Gouader,
  • Mouna Kriaa,
  • Wafa Jallouli,
  • Souad Rouis

摘要

Background

To develop a new generation of eco-friendly biopesticides, this study used an optimized random mutagenesis approach to generates oligosporogenic mutants from B. thuringiensis var. kurstaki BLB1. Although random mutagenesis is not a novel approach, it remains a practical and efficient strategy providing a simple and accessible alternative.

Results

Screening of over than 600 mutants showed that only 14 clones harbour less rate of spores ranging from 1 ± 0.5 10–6 to 126 ± 1 10–6 spores ml−1. Among them, a number of 6 mutants showed an improvement of delta-endotoxins until 222.92%. Protease production showed that S6 mutant exhibited the most increased rate of about 4136.36 U ml−1 ± 89.65 in addition to its enhancement of 34,96% in delta-endotoxins production. Captively, S3 and S4 mutants were largely active against A. tumefaciens and three fungi revealing values of MIC and MFC ranging from 0.07 to 0.31 µg ml−1 and from 0.05 to 0.225 µg ml−1 against A. niger, F. culmorum and B. cinerea, respectively. Oligosporogenic S6 mutant was considered as a polyvalent and eco-friendly biopesticide since it is the most toxic against semolina larvae E. kuehniella (LC50 of 39.52 µg g−1). To reduce its production cost, we explored the use of date waste as a cost-effective culture medium. An improvement of 43.15% of delta-endotoxins production of S6 mutant was obtained via Taguchi design while valorising agricultural by-products.

Conclusion

The study successfully generated oligosporogenic mutants of B. thuringiensis BLB1 with enhanced delta-endotoxin and enzyme production while reducing spore formation. The S6 mutant showed the highest bioactivity, and its production was further increased in a cost-effective way using date waste as a culture medium, highlighting its potential as a useful and eco-friendly biopesticide.