MOLECULAR CHARACTERIZATION AND BIOPROSPECTION OF BREVIBACILLUS SP ON CTENOCEPHALIDES FELIS FELIS

Milene Barbosa Gomes (FIOCRUZ/IOC); Fabio Barbour Scott (UFRRJ); Vania Bittencourt (UFRRJ); Viviane Zahner (FIOCRUZ/IOC)

Brevibacillus laterosporus is a microorganism that has show great biotechnologic potential against major disease vectors, but its toxicity levels has not been homogeneous among the isolates. Considered a public health problem, flea Ctenocephalides felis felis, affect mainly dogs and cats by plundered them and took the blood meal being a vector of pathogens. This study aims to identify molecular markers for the major pathogenic strains of the Brevibacillus sp, correlate plasmid profile with pathogenicity and to evaluate the toxicity these bacterium against Ctenocephalides felis felis. In this way, we evaluated 35 strains of  Brevibacillus sp. The technique of RAPD (Random Amplified Polymorphic DNA) using primer OPA11 generated distinct profile for all strains, but one band of approximated 800pb common to all strains of Br laterosporus was also found into Br agri and Br parabrevis. Analysis for the presence of plasmids by pulsed-field gel electrophoresis (PFGE) for the assessment of segments of size up to 5000 Kb indicated the presence of these elements in some strains. In complementation, analysis by extraction of plasmid DNA were performed by KITs and presence of small size plasmids confirmed. In addition bioassay was made with bacterial growth of strains LSB 112 and LSB 136, during vegetative, spore and sporangium free live forms. Bacterial growth were added to the diet offered to fleas, which were divided into 6 groups of 10 individuals each. After 20 days, time needed for the development of eggs until adults in laboratory conditions, the number of adults was counted among the different groups and effectiveness measured in percentage of adults presence. Up to now the sample LSB 112 proved to be the most promising, showing average mortality of 96.7% in vegetative stage.