RESUMO
A bacterium was isolated from the soil of dumping ground for cattle yard waste by enrichment culture containing aflatoxin B1. This bacterium was closely related to Bacillus firmus that was found to be a non-pathogenic bacterium. The minimum inhibitory concentration of aflatoxin B1 to the bacterium was found to be 80 microg ml(-1) as measured by total viable count and soluble protein content methods. The bacterium was sensitive to all the tested antibiotics. Plasmid curing by chemical agents did not show the resistance character residing in the plasmid. Protein profiles of cell extracts of aflatoxin B1 resistant bacterium grown in the presence and absence of the toxin showed 46 and 44 protein bands respectively in SDS-PAGE. It was observed that 39 bands were common in both the extracts and the remaining bands were showing differences near the high molecular weight range.
Assuntos
Aflatoxina B1/toxicidade , Animais , Bacillus/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Bovinos , Farmacorresistência Bacteriana , Contaminação de Alimentos , Plasmídeos/genética , Microbiologia do SoloRESUMO
A bacterium resistant to aflatoxin B1 isolated from the soil was shown to remove a maximum 26% of toxin at 3 microg ml(-1). A comparison of spectrophotometric and radioisotope methods showed that a maximum of 48 hr was sufficient to remove the toxin. Radioisotope analysis showed that the radioactivity decreased in the chloroform phase while it increased in the aqueous phase during the time course of the experiment. An analysis of the supernatant of culture medium showed that the bacterium had converted aflatoxin B1 to water soluble compounds with lambda(max) of 338 and 374.