Lipases and biosurfactants production by the newly isolated Burkholderia sp.

Abstract

Lipases and biosurfactants are biocompounds produced by microorganisms involved in the metabolism of oily substrates. In this way, our study aimed to evaluate these molecules production by bacteria isolated from contaminated soil with waste vegetable oil and evaluate the optimal culture conditions for lipase production using the response surface methodology. The lipolytic activity was tested on tributyrin agar and rhodamine B agar with olive or soybean oil. All 66 isolates of bacteria were positive on tributyrin medium, while the percentage of lipolytic bacteria on rhodamine B medium varied from 31 (soybean oil, pH 6.0) to 38 (olive oil, pH 7.0 and 8.0; soybean oil, pH 8.0). The oil-spreading technique revealed that all isolates produced biosurfactants and oil emulsification and hemolytic activity tests detected biosurfactants in 60% and 88% of isolates, respectively. Lipolytic activity and biomass value varied de 8.7 to 12.4 U/mL and 2.5 to 4.04 mg/mL, respectively, in nutrient broth with olive oil medium. Six isolates with higher lipase activity were identified as Burkholderia sp., according to phylogenetic analysis based 16S rRNA sequences. Only Burkholderia sp. O19 strain produced rhamnolipids among bacteria studied. The surface response methodology revealed that the production of lipases by Burkholderia sp. O19 occurs in a wide range of pH and temperature with maximum response achieved at pH 8.5 and 65 °C (18.7 U/mL). The results obtained in this study are relevant as they show the simultaneous production of two biocompounds with broad industrial applications.