title: Selection of biosurfactan/bioemulsifier-producing bacteria from hydrocarbon-contaminated soil.
abstract: Petroleum-derived hydrocarbons are among the most persistent soil contaminants, and some hydrocarbon-degrading microorganisms can produce biosurfactants to increase bioavailability and degradation. The aim of this work was to identify biosurfactant-producing bacterial strains isolated from hydrocarbon-contaminated sites, and to evaluate their biosurfactant properties. The drop-collapse method and minimal agar added with a layer of combustoleo were used for screening, and positive strains were grown in liquid medium, and surface tension and emulsification index were determined in cell-free supernantant and cell suspension. A total of 324 bacterial strains were tested, and 17 were positive for the drop-collapse and hydrocarbon-layer agar methods. Most of the strains were Pseudomonas, except for three strains (Acinetobacter, Bacillus, Rhodococcus). Surface tension was similar in cell-free and cell suspension measurements, with values in the range of 58 to 26 (mN/m), and all formed stable emulsions with motor oil (76-93% E24). Considering the variety of molecular structures among microbial biosurfactants, they have different chemical properties that can be exploited commercially, for applications as diverse as bioremediation or degradable detergents.
authors.affiliation: Facultad de Ciencias Químicas, Universidad Autónoma de Chihuahua , P.O. Box 1542- C Chihuahua, Chih. , Mexico.
authors.forename: Sabina
authors.initials: S
authors.lastname: Viramontes-Ramos
authors.forename: Martha
authors.initials: M
authors.lastname: Cristina Portillo-Ruiz
authors.forename: María de Lourdes
authors.initials: Mde L
authors.lastname: Ballinas-Casarrubias
authors.forename: José Vinicio
authors.initials: JV
authors.lastname: Torres-Muñoz
authors.forename: Blanca Estela
authors.initials: BE
authors.lastname: Rivera-Chavira
authors.forename: Guadalupe Virginia
authors.initials: GV
authors.lastname: Nevárez-Moorillón
keywords: bioemulsifiers; biosurfactants; hydrocarbon contamination; soil microbiota
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