Promising active bioinsecticides produced by Bacillus thuringiensis strain BLB427
1 Laboratory of Biopesticides, Centre of Biotechnology of Sfax, 3018 Sfax, Tunisia
2 Department of Biology, Faculty of Sciences and Arts-Khulais, University of Jeddah, Saudi Arabia
3 Higher Institute of Biotechnology of Sfax, University of Sfax, Tunisia.
# These authors contributed equally to this work.
Research Article
World Journal of Advanced Research and Reviews, 2020, 08(01), 026-035
Article DOI: 10.30574/wjarr.2020.8.1.0358
Publication history:
Received on 20 September 2020; revised on 27 September 2020; accepted on 29 September 2020
Abstract:
Bacillus thuringiensis is gaining worldwide importance in the control of pests in agriculture and public health. Characterization of new isolated strains with original, higher and broader spectrum of activity is an ever developing field. Parasporal inclusions from BLB427, a new B. thuringiensis strain isolated from Tunisian soil, contained 2 major Cry proteins having molecular weights of about 130-135 kDa and 65-70 kDa corresponding to cry1-type and cry2-type genes, respectively. These toxins exhibited high toxicities to Ephestia kuehniella and Spodoptera littoralis larvae, with LC50 values of about 81.91 µg/cm2 (+/- 15.30) and 79.70 µg/cm2 (+/- 36.73), respectively. BLB427 supernatant showed a promising activity against Lepidopteran pests due to the presence of vip3-type gene in this strain. The high toxicity of BLB427 supernatant compared to that of BUPM95, used as control, was due in part to the high copy number of vip3 gene of BLB427 compared to that of vip3Aa16 of BUPM95, as demonstrated by Real-time PCR. This gene was cloned, sequenced and the comparison with the most known vip3 genes in databases, demonstrated that vip3(427) gene and the corresponding protein showed differences that can influence the efficiency of the Vip3(427) toxin against Lepidoptera. After overexpression of Vip3(427) protein in Esherichia coli and its purification using His-Trap column, the toxin showed a promising toxicity against the lepidopteran pest S. littoralis with extremely damages in the larvae midgut traduced by the vacuolization of the apical cells, the damage of microvilli and the disruption of epithelial cells. The results described in the present study proved that B. thuringiensis BLB427 strain could be of a great interest for lepidopteran biocontrol by using its d-endotoxins and/or Vip3 toxins in bioinsecticides formulations.
Keywords:
Bacillus thuringiensis; biocontrol; Delta-endotoxins; Vip3; Ephestia kuehniella; Spodoptera littoralis.
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