Phenotypic and genotypic analyzes of the autoagglutinating strains of Bacillus thuringiensis
Twenty eight ?autoagglutinating? strains of Bacillus thuringiensis were studied by using through phenotypic and genotypic methods, aiming to evaluated the intra-specific similarity and homogeneity between them. Strains were isolated from different ecologic niches and distinct sites and could not be serologically typed. Biological activity was evaluated through bioassays against two species of mosquitoes: Aedes aegypti (vector of Dengue and Yellow Fever) and Culex quinquefasciatus (vector of Bancroftian Filariasis). The results of the larvicidal activity demonstrated that 26 ?autoagglutinanting? strains were toxic to mosquitoes-vectors (mortality gt; 50%) and two strains presented low toxicity (mortality among 0% to 20%). The phenotypic characters of these bacterial strains demonstrated in their majority the same peculiar properties for the species under study. The resistance profiles of strains revealed multiple resistance to antimicrobials, being all these 28 ?autoagglutinanting? strains 100% resistant to six antimicrobials Bacitracin, Lincomycin, Polymyxin B, Penicillin G, Rifampicin, Vancomycin and only two Netilmicin and Sulphamethoxazole/Trimethoprim, showed 100% of inhibition. The protein profiles of crystals components revealed four classes with distinctive protein patterns. The main class includes 23 mosquitocidal strains, which demonstrated the same protein profile of the serovar israelensis. Using isoenzyme analysis (MLEE), it was observed the presence of three electrophoretic types (ETs). The mosquitocidal strains grouped into one ET. The random amplified polymorphic DNA analysis (RAPD) was evaluated using six primers, which demonstrated three different patterns for the 28 ?autoagglutinanting? strains, allowing to correlate the profiles obtained with the toxicity observed in the bioassays. The RAPD patterns established by mosquitocidal strains, demonstrated to be identical to the one of serovar israelensis. However, to strains of low toxicity, each primer established distinctive RAPD patterns, which demonstrated that these strains belongs to different serovars. Although the flagellar serotyping has not been identified the 26 ?autoagglutinanting? strains of Bacillus thuringiensis, MLEE and RAPD profiles were compatible to that of Bacillus thuringiensis serovar israelensis.
Advisor:Leon Rabinovitch; Clara de Fátima Gomes Cavados
School:Faculdades Oswaldo Cruz
Source Type:Master's Thesis
Keywords:Bacillus thuringiensis Phenotype Genotype BIOFISICA MOLECULAR
Date of Publication:08/24/2006