title: Molecular characterization of mosquitocidal Bacillus sphaericus isolated from Tamil Nadu, India.
abstract: Forty-two Bacillus sphaericus strains were isolated from soil around Tamil Nadu, India. The phylogenetic relationship among the B. sphaericus isolates was analysed by REP-PCR and multiplex PCR was performed for the detection of mosquito larvicidal genes binA, binB, mtx1, mtx2 and mtx3 in B. sphaericus isolates. According to the REP-PCR band pattern, B. sphaericus isolates were divided into group A comprising I-XI clusters and group B comprising cluster XII. Three of the isolates BSTN01, 23 and 24 were gathered under cluster XII showed a high level of larvicidal activity against Culex quinquefasciatus and Anopheles stephensi, the other 39 isolates grouped under I-XI clusters were non-toxic or weak or moderately toxic to mosquito larvae. Even though BSTN23 and 24 were isolated from the same location and both contained all the five mosquito larvicidal genes, their intraspecies difference was clearly elucidated by REP-PCR analysis. Among high toxic isolates, BSTN23 and 24 were observed to contain all the five toxin genes and BSTN01 showed the presence of binary toxin and Mtx1 toxin genes. The isolates BSTN02, 03, 07, 14, 16, 19, 20, 21, 25, 31, 36 and 39 were found to contain mtx1 gene with combination of mtx2 and/or mtx3 showed moderate or low toxicity against mosquito larvae. binA, binB and mtx1 genes were not present in non-toxic isolates. The present study revealed the genetic heterogeneity between both toxic and non-toxic isolates and indicates that there is a good correlation between the presence of toxin genes and toxicity of the strains. These techniques could be developed in screening of novel highly toxic B. sphaericus strains from environment without bioassay on mosquito larvae.
authors: Department of Biotechnology, Anna University - BIT Campus, Tiruchirappalli 620024, India.
authors: D Immanual Gilwax
authors: DI
authors: Prabhu
authors: S Gowri
authors: SG
authors: Sankar
authors: P Thirumalai
authors: PT
authors: Vasan
authors: P Sobana
authors: PS
authors: Piriya
authors: B Karpanai
authors: BK
authors: Selvan
authors: S John
authors: SJ
authors: Vennison
mesh_terms: D000818:Animals; D001407:Bacillus / Q000145:classification* / Q000302:isolation & purification* / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D003465:Culex / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D007194:India; D007814:Larva / Q000382:microbiology; D009032:Mosquito Control / Q000379:methods*; D010572:Pest Control, Biological / Q000379:methods*; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods
chemical_list: D001427:Bacterial Toxins
keywords: Bacillus sphaericus; Binary toxin; Dendrogram; Mosquitocidal toxin; Multiplex PCR; REP-PCR