Otimização da produção de biossurfactante

Abstract

Surfactants are chemical species, and their molecules have hydrophilic parts and hydrophobic parts. The vast majority of commercially available surfactants are synthesized from petroleum derivatives. Although, surfactants are widely used in the industries, they cause damage to the environment, so it is necessary to replace them with products with the same properties and that are not so harmful to the environment. The microbial compounds which exhibit surfactant properties, this is, reduce the surface tension and have high emulsifying capacity, are termed biosurfactants and consist of metabolic byproducts of bacteria, fungi and yeast. In order to study the production of biosurfactant, the present work evaluated two microorganisms, a strain of Aureobasidum pullulans and one of Bacillus subtilis using two different types of bioreactor, a mechanical agitation reactor (STR) and an airlift bioreactor. The biomass and the emulsification and surface tension index of the biosurfactant are determined in order to qualify the bioproduct. The results show that the studied strain of Aureobasidum pullulans produces a bioemulsifier (does not reduce the surface tension) and the Bacillus subtilis strain produces the biosurfactant (surfactin), product of interest, being able to reduce from 72 mN.m-1 to 30 mN.m-1, approximately, the surface tension of the water. The biosurfactant was also stable, as it did not vary its properties in face of variations of pH, ionic strength and temperature. Thus, it is possible to apply industrially.