Produção de biossurfactante por Mucor sp. e Rhizopus sp. e aplicação na biorremediação de amostras de água e solo contaminados por petróleo.

Abstract

During the process of extraction until commercialization of petroleum, several activities are potentially dangerous to the environment due to the high leak risk of petroderivatives in aquatic and terrestrial environments. In this context, a solution for removing of petroleum and derivatives is the application of biosurfactants defined as natural and biodegradable compounds produced by microorganisms. Thus, the objective of this work was produce, extract and characterize the biosurfactant produced by species of Mucor circinelloides and Rhizopus arrhizus and apply in bioremediation of soil and water impacted with petroleum and derivatives, developing a viable and eco-sustainable bioprocess. The studies started with the application of a 23 factorial design using agro-industrial residues such as corn steep liquor, post-frying oil and instant noodle residue as nutrients in production medium for four isolates of the order Mucorales (Mucor circinelloides UCP 0005, Mucor circinelloides UCP 0006, Mucor circinelloides UCP 0006, Mucor circinelloides UCP 0042 and Rhizopus arrhizus UCP 1609). Cultivation conditions were pH 5.5 in submerged fermentation, orbital agitation at 150 rpm for 96 h. The four isolates of the order Mucorales were able of use substrates as nutritional sources to produce biosurfactants. However, the strain that showed the greatest reduction in surface tension (72 to 27 mN/m) was M. circinelloides UCP 0006 in condition 3 of the design (1% residue of instant noodles, 4% cornstarch, in the absence of soybean oil post-frying). Statistical analysis carried out using the Pareto diagram confirms the important influence of corn steep liquor and post-frying oil in reducing surface tension. The emulsification index presented by M. circinelloides UCP 0005 was significant (70%) when compared to the values obtained by the species of Rhizopus arrhizus UCP 1609 (60% in condition 8) and M. circinelloides UCP 0006 (55.2% in condition 3 ). On the other hand, M. circinelloides UCP 0042 was cultivated in a new production medium (containing different concentrations of corn steep liquor, post-frying oil and instant noodle residue) according to factorial design. According to the results obtained, in condition 7 of the planning (1% instant noodle waste, 4% corn steep liquor and 1% post-frying oil) the maximum reduction in surface tension occurred (72 to 24 mN/m). In addition, the potential of the biosurfactant produced by Mucor circinelloides UCP 0042 in the removal of diesel oil in sandy soil was evaluated. The biosurfactant produced was able of remove 78% of diesel oil from beach sand, beyond of having the potential of disperse petroderivatives in water (33.2 cm2 ODA) and degrade 93% of petroderivatives, confirming the ability of Mucor circinelloides UCP 0042 to produce biosurfactant of high industrial and environmental interest.