Preliminary Investigation on the Production of Surface Active Compounds With Antimicrobial and Emulsifying Properties by Bacillus Clausii and Lactobacillus Rhamnosus Probiotic Strains

Abstract

Surface active compounds (SACs) of bacterial origin are amphiphilic heteropolymers that may alter the interaction of gas-liquid, solid-liquid, and immiscible liquids surfaces, decrease the surface and interfacial tensions of liquids, and form stable emulsions. SACs are divided in two main groups: low molecular weight, the biosurfactants, and high molecular weight, the bioemulsifiers. Probiotics are live microorganisms that, when administered in determined levels, provide benefits to the host. They can produce SACs with several properties, such as the emulsification and solubilization of substrates and antimicrobial activity. Here we show that the cell-free supernatant of commercial probiotic strains of Bacillus clausii (formerly Bacillus subtilis), a spore-forming species that can tolerate biliary salts and survive at acid gastric conditions, and Lactobacillus rhamnosus, a lactic acid facultative heterofermentative bacterial species, are able to emulsify apolar fluids including gasoline fuel, suggesting the presence of biomolecules that could be explored for bioremediation. L. rhamnosus also presented antimicrobial activity, whereas Bacillus clausii did not.