Estudo da produção e aplicabilidade de biossurfactante bacteriano produzido por Cepa isolada de manguezal cearense

Abstract

The high demand for chemical surfactants in the worldwide market has increased the interest on biosurfactants, which are biodegradable substances produced by bacteria, yeasts and fungi. In this context, this work aims to study the biosurfactant production by a strain isolated from a Brazilian mangrove, as well evaluate its functional properties and applicability. The results has presented that the biosurfactant produced by strain ICA56, in mineral medium, was capable to reduce the surface tension of water from 72 to 30 mN.m-1 and interfacial tension on a water/gasoline system from 15 to 3 mN.m-1, showing its efficiency as a tensoative. The biosurfactant was capable to produce stable emulsion on some hydrophobic sources, as motor oil, soybean oil, hexane and kerosene. The emulsifying and tensoative properties of the bioproduct formed on ICA56’s cultivation have showed some stability through the environmental variations of pH, temperature and saline concentration, presenting some evidences of its wide applicability. Another result which proves the efficiency for the biosurfactant produced is the critical micelle concentration around 25 mg.L-1. The biosurfactant produced was able to remove hydrocarbons and heavy metals in contaminated environments simulating systems, presenting efficiency when it’s compared to chemical surfactants. Despite the efficiency of the functional properties and applicability of the biosurfactant, the production in mineral medium was around 200 mg.L-1, which is a reasonable concentration. So, it was evaluated 2 alternatives in order to increase the biosurfactant production: the influence of oxygen transfer and the use of unconventional substrates. The variation of agitation and aeration in bioreactor didn’t seemed to present such a significant result, showing that the operational condition of 200 rpm for agitation and 1 L.min-1 for aeration was the best among the tested conditions for biosurfactant production. However, the use of unconventional substrates proved to be a better alternative in order to increase the biosurfactant production, as well as reducing costs in the process, as higher yields were observed in comparison to mineral medium. Substrates such as sunflower oil and glycerol are presented as potential carbon sources for biosurfactant production by strain ICA56, obtaining concentrations of 870 mg.L-1 and 1420 mg.L-1 of the product of interest, in its raw form, respectively.