Presumptive relationship between the production of bioemulsifier and the lipase activity in a hydrocarbon-degrading actinobacterium

GOMEZ JOHANA; BOURGUIGNON NATALIA; FERRERO MARCELA; GIANNI KATIA; FUENTES MARIA SOLEDAD; COLIN VERÓNICA LETICIA

Workshop; V International Workshop. Advances in Science and Technology of Bioresources.; 2015

Bioemulsifiers are amphiphilic compounds produced by diverse microorganisms that improve the solubility of water immiscible substrates. Many microorganisms have been identified as bioemulsifier producers. However, there are few studies related to their joint production with lipases, enzymes related to degradation of oily substance. The actinobacterium Streptomyces sp. CC10 isolated from marine environments have been previously identified as a hydrocarbon-degrading microorganism. In the present work, strain?s ability to produce emulsifiers together with lipase has been evaluated for the first time. A spore suspension of the strain was inoculated in defined liquid cultures media, where two carbon sources (glycerol or vinasse, 1.0% v/v) were combined with two nitrogen sources (urea or peptone, 0.1% w/v), and incubated on orbital shaker at 30 ºC during 96 h. Microbial growth was determined by drying washed biomass at 105 °C until constant weight. Bioemulsifier production was estimated by determination of emulsification index (EI) of culture supernatants using motor oil as substrate hydrophobic; while the lipase activity was measured spectrophotometrically at 405 nm using p-nitrophenyl palmitate (p-NPP) as substrate. The main effects of carbon and nitrogen sources on biomass concentration were significant, with a maximum bacterial growth in presence of glycerol and peptone (0.9 ± 0.01 g/L). Significant IE values and lipase activities were also detected in all cultures. However, both parameters were strongly affected by carbon and nitrogen substrates as well as by the interaction between them. Interestingly, a high correlation between the IE and enzymatic activity was detected (r=0.762). These results suggests that both metabolites, bioemulsifier and lipase, could be synthetized as part of a microbial complex related to the degradation?s mechanisms of hydrophobic compounds.