RESUMO
A strain of Bacillus amyloliquefaciens (VCRC B483) exhibiting mosquito pupicidal, keratinase and antimicrobial activities was isolated from mangrove forest ecosystem of Andaman and Nicobar Islands. Molecular characterization of the strain showed the presence of lipopeptide encoding bmyC gene. Phylogenetic tree based on protein sequence of this gene exhibited homology with mycosubtilin synthetase of Bacilus atropheus and Iturin synthetase of Bacillus subtilis and B. amyloliquefaciens. This is the first report on the evolutionary conservation of amino acids concerned with the function and structure of bmyC protein of B. amyloliquefaciens. The presence of valine at the 1197th position in our strain was found to be unique and different from the existing strains of B. subtilis and B. amyloliquefaciens. Molecular modelling studies revealed significant changes in the structure of epimerization domain of the bmyC protein with A1197V variation. Crude metabolite of this strain exhibited antifungal activity against Fusarium sp. and Carvularia sp.
Assuntos
Antifúngicos/farmacologia , Bacillus amyloliquefaciens/genética , Bacillus amyloliquefaciens/metabolismo , Culicidae/microbiologia , Genes Bacterianos/genética , Peptídeos/genética , Sequência de Aminoácidos , Animais , Antifúngicos/metabolismo , Peptídeos Catiônicos Antimicrobianos , Bacillus/enzimologia , Bacillus/genética , Bacillus amyloliquefaciens/enzimologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/farmacologia , Fusarium/efeitos dos fármacos , Lipopeptídeos/genética , Lipopeptídeos/metabolismo , Modelos Moleculares , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/farmacologia , Peptídeos/farmacologia , Filogenia , Alinhamento de Sequência , Homologia de SequênciaRESUMO
BACKGROUND & OBJECTIVES: Bacillus thuringiensis var. israelensis (Bti) formulations are presently being used for insect control. In this study, a water dispersible powder (WDP) formulation using fly ash (FA) as a carrier material was developed and studied for its activity against the larval stages of major mosquito vector species. METHODS: An indigenous isolate Bti (Vector Control Research Centre B17) was mass produced using a 100 l fermentor in soya-based medium. The bacterial biomass was mixed with lignite FA and made into WDP formulations. The most effective formulation was used for determining 50 per cent lethal concentration (LC50) against the larval stages of major mosquito vector species, effect on non-target organisms and mammalian systems using standard protocols. RESULTS: Sixteen types of WDP formulations were prepared, of which the formulation containing bacterial biomass, FA and carboxymethyl cellulose was found to be the most effective. The LC50values of the formulation against Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi larvae were 0.0417, 0.0462 and 0.1091 mg/l, respectively. The formulation was found to be safe to non-target organisms found associated with the mosquito larval stages and also to mammalian systems. INTERPRETATION & CONCLUSIONS: The study shows that FA can be effectively used to replace commercially available carrier materials used in biopesticidal formulations.
Assuntos
Bacillus thuringiensis/química , Controle de Insetos , Controle Biológico de Vetores , Animais , Carboximetilcelulose Sódica/química , Carboximetilcelulose Sódica/farmacologia , Cinza de Carvão/química , Larva/efeitos dos fármacos , Larva/patogenicidade , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/patogenicidade , Pós/química , Pós/farmacologia , Glycine max/parasitologia , Água/químicaRESUMO
BACKGROUND: Anopheles culicifacies, a major malarial vector has been recognized as a complex of five sibling species, A, B, C, D and E. These sibling species exhibit varied vectorial capacity, host specificity and susceptibility to malarial parasites/ insecticides. In this study, a PCR assay developed earlier for distinguishing the five individual species was validated on samples of An. culicifacies collected from various parts of India. METHODS: The samples were initially screened using the rDNA-ITS2 region based primers which categorised the samples into either A/D group or B/C/E group. A proportion of samples belonging to each group were subjected to the mtDNA-COII PCR assay for identifying individual species. RESULTS: Among the 615 samples analysed by rDNA-ITS2 PCR assay, 303 were found to belong to A/D group and 299 to B/C/E group while 13 turned negative. Among 163 samples belonging to A/D group, only one sample displayed the profile characteristic of species A and among the 176 samples falling in the B/C/E group, 51 were identified as species B, 14 as species C and 41 as species E respectively by the mtDNA-COII PCR assay. Samples exhibiting products diagnostic of B/C/E, when subjected to PCR-RFLP assay identified 15 samples as species E. CONCLUSION: Validation of the mtDNA-COII PCR assay on large number of samples showed that this technique cannot be used universally to distinguish the 5 members of this species complex, as it has been designed based on minor/single base differences observed in the COII region.
