Abstract
ABSTRACTIn this work a Bacillus strain with capacity to produce biosurfactants was isolated from commercial corn steep water (CSW). The identification of this bacterium was based on phenotypic characteristics. This is a Gram-positive Bacillus, macroscopically catalase-negative, that possesses high mobility and forms terminal endospore. The colonies formed by the isolated Bacillus strain are characterized by a creaming, dull and glistening phenotype with a small point-like elevation in the center. Regarding its antimicrobial activity, the isolated Bacillus strain was effective against Candida albicans and Staphylococcus aureus observing, in the presence of pathogenic strains, a phenotype dissociation, switching the colonies from a whitish to yellowish pigmentation. The isolated microorganism, contrarily to other Bacillus strains, has the ability to produce extracellular and cell-bound biosurfactants. The analyses revealed that both biosurfactant extracts are similar to the lipopeptide biosurfactant produced by Bacillus subtilis.
Highlights
Biosurfactants are biocompatible and biodegradable surfaceactive compounds produced by microorganisms
This industrial stream is characterized by a high viscosity, low concentration of sugars and high concentration of lactic acid, which has been employed by many researchers as nutritional supplement in the production of microbial metabolites (Guerra-Rodríguez & Vázquez, 2013)
The Bacillus isolated from corn steep water (CSW) showed to have ability to produce terminal endospores as well as to exhibit a pigmentation trait that switches from whitish to yellowish in the presence of pathogenic microorganisms
Summary
Biosurfactants are biocompatible and biodegradable surfaceactive compounds produced by microorganisms. In contrast to most surfactants, which are obtained by chemical synthesis, biosurfactants present features such as good efficiency and low levels of toxicity and irritation in addition to the fact that they are environmentally friendly They can be used to help in solubilisation and stabilization of emulsions and to enhance the sensory and rheological characteristics of mixtures including food formulations (Santos, Rufino, Luna, Santos, & Sarubbo, 2016). Vecino et al (2014) have proven that corn steep water (CSW), a fermented residual stream of corn-milling industry, is a direct source of biosurfactants due to the spontaneous growth of microorganisms producing biosurfactants. These microorganisms have not been isolated at the moment
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