title: Isolation and characterization of a new Bacillus thuringiensis strain with a promising toxicity against Lepidopteran pests.
abstract: Insecticides derived from Bacillus thuringiensis are gaining worldwide importance as environmentally desirable alternatives to chemicals for the control of pests in public health and agriculture. Isolation and characterization of new strains with higher and broader spectrum of activity is an ever growing field. In the present work, a novel Tunisian B. thuringiensis isolate named BLB459 was characterized and electrophoresis assay showed that among a collection of 200 B. thuringiensis strains, the plasmid profile of BLB459 was distinctive. SmaI-PFGE typing confirmed the uniqueness of the DNA pattern of this strain, compared with BUPM95 and HD1 reference strains. PCR and sequencing assays revealed that BLB459 harbored three cry genes (cry30, cry40 and cry54) corresponding to the obtained molecular sizes in the protein pattern. Interestingly, PCR-RFLP assay demonstrated the originality of the BLB459 cry30-type gene compared to the other published cry30 genes. Insecticidal bioassays showed that BLB459 spore-crystal suspension was highly toxic to both Ephestia kuehniella and Spodoptera littoralis with LC50 values of about 64 (53-75) and 80 (69-91) μg of toxin cm(-2), respectively, comparing with that of the commercial strain HD1 used as reference. Important histopathological effects of BLB459 δ-endotoxins on the two tested larvae midguts were detected, traduced by the vacuolization of the apical cells, the damage of microvilli, and the disruption of epithelial cells. These results proved that BLB459 strain could be of a great interest for lepidopteran biocontrol.
authors.affiliation: Laboratory of Biopesticides, Centre of Biotechnology of Sfax, P.O. Box "1177", 3018 Sfax, Tunisia.
authors.forename: Hanen
authors.initials: H
authors.lastname: Boukedi
authors.affiliation: Laboratory of Biopesticides, Centre of Biotechnology of Sfax, P.O. Box "1177", 3018 Sfax, Tunisia.
authors.forename: Sameh
authors.initials: S
authors.lastname: Sellami
authors.affiliation: Laboratory of Microbiology, Medical School of Sfax, CHU Habib-Bourguiba, Sfax, Tunisia.
authors.forename: Sonia
authors.initials: S
authors.lastname: Ktari
authors.affiliation: Laboratory of Biopesticides, Centre of Biotechnology of Sfax, P.O. Box "1177", 3018 Sfax, Tunisia.
authors.forename: Najeh
authors.initials: N
authors.lastname: Belguith-Ben Hassan
authors.affiliation: Laboratory of Anatomy and Pathological Cytology, CHU Habib-Bourguiba, Sfax, Tunisia.
authors.forename: Tahya
authors.initials: T
authors.lastname: Sellami-Boudawara
authors.affiliation: Laboratory of Biopesticides, Centre of Biotechnology of Sfax, P.O. Box "1177", 3018 Sfax, Tunisia.
authors.forename: Slim
authors.initials: S
authors.lastname: Tounsi
authors.affiliation: Department of Biology, Faculty of Sciences and Arts-Khulais, University of Jeddah, Saudi Arabia. Electronic address: mesratilobna@yahoo.com.
authors.forename: Lobna
authors.initials: L
authors.lastname: Abdelkefi-Mesrati
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity*; D001681:Biological Assay; D016172:DNA Fingerprinting; D016521:Electrophoresis, Gel, Pulsed-Field; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity*; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity*; D007915:Lepidoptera / Q000187:drug effects* / Q000502:physiology*; D010957:Plasmids / Q000032:analysis; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D016019:Survival Analysis; D014416:Tunisia
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bacillus thuringiensis; Ephestia kuehniella; PCR-RFLP; PFGE; Spodoptera littoralis; cry-type gene