Produção, extração, purificação e potencial atividade antimicrobiana do biossurfactante produzido por Bacillus safensis MF326565 isolado de solo canavieiro

Abstract

Surfactants are amphipathic molecules capable of interacting with surfaces of different polarities and because they are derived from petroleum, they have limitations and problems associated with their use, among which environmental ones stand out. Biosurfactants are an alternative because they demonstrate environmentally desirable characteristics that depend on the metabolism of organisms, associated with technologies that favor their production. In this context, we highlight the use of sugarcane molasses as an alternative source of substrate. Therefore, the objective of this work was to produce biosurfactant in bench top bioreactor using Bacillus safensis, MF326565, isolated from sugarcane soil and sugarcane molasses as an alternative substrate. The experiments were carried out preliminarily in shaker (1% of sugarcane molasses and 1% of yeast extract - w / v). The diagnosis of biosurfactant production was made by growth analysis, surface tension and emulsification index. In bioreactor, they followed the same analyzes, besides the characterization by FTIR and evaluation of antimicrobial activity. The results of shaker cultivation were quite satisfactory regarding growth and biosurfactant production, since the microorganism was able to use the substrate and produce biosurfactant, which presented emulsification index higher than 50% in motor oil, besides presenting reduction. surface tension by 32%. In bioreactor a growth of approximately 3.0 g / l of biomass and 1.5 g / l of biosurfactant was observed and with much higher emulsification in motor oil, vegetable oil and kerosene. The biosurfactant showed stability at temperature (15 ~ 60 ° C), pH (2.0 ~ 8.0), salinity (6 ~ 10% NaCl), and emulsification remained stable for more than 15 days. Infrared spectrograms (FTIR) of the purified product from the bioreactor experiments showed similarity with the surfactin standard, showing its lipopeptide nature. The biosurfactant showed antimicrobial activity against S. aureus, B. cereus, B. safensis, B. subtilis, C. albicans and Acinetobacter sp., bactericidal activity at concentrations of 12.5 mg / mL for Acinetobacter sp. and S. aureus and concentrations below 3.0 mg / mL for Bacillus used in this study. Thus, it is concluded that Bacillus safensis, MF326565, was able to produce biosurfactant from an alternative substrate (molasses from sugarcane) and that it was effective in emulsifying hydrophobic compounds, besides presenting biological activity