Detecção de antagonismo em bactérias halotelerantes do lago Itaipu – Santa Helena, PR

Abstract

The phylum Actinobacteria is composed of Gram-positive bacteria well known for its capacity to synthesize a wide variety of bioactive compounds such as enzymes and antimicrobials employed in many human activities. Based on this theorical assumptions, the purpose of this research was to isolate the halotolerant actinobacteria from Itaipu Lake to verify their antagonism capacity against some pathogens of clinical and economic interest. Nine halotolerant isolates could be established at 7% NaCl concentration whose antagonistic activity could be detected by two distinct antimicrobial tests: agar diffusion, against yeast and statistics; and radial growth, against filamentous fungi. The antagonism was observed in six out of nine microbial isolates, in other words, more than half of the samples expressed inhibitory activity. The antimicrobial agar diffusion test showed inhibition of Bacillus cereus growth by four out of nine halotolerant isolates. Regarding the antifungal activity test, four out nine halotolerant isolates showed antimicrobial activity that inhibited Fusarium graminearum growth, and at least one of the microbial isolates expressed antagonism against Trichophyton rubrum. This study showed that Itaipu Lake, which receives water from rivers that drain part of the West of the country, may have a significant number of promising isolates for the production of molecules of interest.