Morphological diversity and toxicity of delta-endotoxin produced by various strains of Bacillus thuringiensis

Abstract

Local isolates of Bacillus thuringiensis were isolated from infected rice stemborers, soils, rice bran and rice mill dust. Of 83 isolates serotyped by B. thuringiensis H-antisera, 13 serotypes were identified. Those serotypes were assigned to B. thuringiensis of subspecies canadensis, galleriae, kenyae, kurstaki, neoleonensis, aizawai, alesti, entomocidus, tochigiensis and tolworthi. Three serotypes, 3a:3c:3d, 5a:5b/21 and 17/27, were unnamed and portend to be new subspecies. Morphological studies of delta-endotoxin or crystal protein of each subspecies showed significant differences in size and shape. Bipyramidal crystals, spherical and cuboidal crystals and the combinations of these structures were observed. Toxicity of sporulated cultures and isolated crystal proteins of B. thuringiensis strains to five species of economically important insects were determined using diet incorporation bioassays. Extracted crystal proteins from certain B. thuringiensis subspecies were highly toxic to some insect species. These have the potential of providing alternative strategies for utilizing B. thuringiensis for controlling insects.

New Bacillus thuringiensis strain isolated from the gut of Malabari goat is effective against Tetranychus macfarlanei

“…kurstaki on 10% potato flour ) and 30% soya bean flour (Jisha et al 2014) supplemented LB medium (solid-state fermentation), respectively, against unsupplemented LB liquid medium. Polymorphic d-endotoxin crystals were produced by the Bt strain reported in this study; similarly bipyramidal, cuboidal and spherical crystals or the combinations of these structures were produced by various strains of Bt (Attathom et al 1995). Interestingly, spindle-shaped crystals (as reported herein) were also produced by a non-toxic strain of Bt subsp.…”

“…Polymorphic δ ‐endotoxin crystals were produced by the Bt strain reported in this study; similarly bipyramidal, cuboidal and spherical crystals or the combinations of these structures were produced by various strains of Bt (Attathom et al. ). Interestingly, spindle‐shaped crystals (as reported herein) were also produced by a non‐toxic strain of Bt subsp.…”

Molecular characterization of indigenous Bacillus thuringiensis strains isolated from Kashmir valley

“…B. thuringiensis strains were isolated from different agro-climatic regions of India (Prabagaran et al 2002). In the present study, Because of the diversity in climatic conditions, the sporulation stage of B. thuringiensis strains and the presence of cry genes may vary (Attathoma et al 1995). Variations observed in the morphology of crystalline inclusions in our Bt strains suggested the presence of diversity in these strains from Kashmir.…”

<htm> <i> Bacillus thuringiensis</i> var. <i>kurstaki</i> (Bacillaceae): potencial no controle, no desenvolvimento e reprodução de <i>Oxydia vesulia </i>(Geometridae), em laboratório</htm>

“…Estudos demonstram que o B. thuringiensis var. kurstaki pode ser considerado um bioinseticida eficaz para lepidópteros (HABIB & ANDRADE, 1986;ATTANTHON et al, 1995;BEHLE et al, 1997). SIMS (1995) afirma que a proteína CryIA (c) do B. thuringiensis, presente em algodão transgênico, tem atividade biológica específica para lepidópteros, não afetando outros insetos.…”