title: Biosurfactant production by the crude oil degrading Stenotrophomonas sp. B-2: chemical characterization, biological activities and environmental applications.
abstract: In this work, biosurfactant-producing microorganisms were isolated from hydrocarbon-contaminated water collected from Tunisian oilfield. After enrichment and isolation, different bacterial strains were preliminary studied for their biosurfactant/bioemulsifier properties when using crude oil as the unique carbon source. In particular, the isolate strain B-2, a Gram-negative, rod-shaped bacterium, efficiently emulsified crude oil. The extracellular biosurfactant product from this strain presented an emulsification activity above 70% and a hydrophobicity of 71%. In addition, a diameter of 6 cm was observed in the oil displacement test. The characterization of B-2 strain using 16S rDNA sequencing enables us to find a high degree of similarity with various members of the genus Stenotrophomonas (with a percentage of similarity of 99%). The emulsification activity of Stenotrophomonas biosurfactant B-2 was maintained in a wide range of pH (2 to 6), temperature (4 to 55 °C), and salinity (0 to 50 g L-1) conditions. It also enhanced the solubility of phenanthrene in water and could be used in the re-mobilization of hydrocarbon-contaminated environment. In addition, this biosurfactant exhibited antimicrobial and antioxidant properties. Infrared spectroscopy suggested potential lipidic and peptidic moieties, and mass spectrometry-based analyses showed that the biosurfactant contains mainly cyclic peptidic structures belonging to the class of diketopiperazines. Therefore, the B-2 strain is a promising biosurfactant-producing microorganism and its derived biosurfactant presents a wide range of industrial applications.
authors.affiliation: Laboratoire d'Electrochimie et Environnement, Ecole Nationale d'Ingénieurs de Sfax, Université de Sfax, BP 1173, 3038, Sfax, Tunisia.|Institut Supérieur de Biotechnologie de Sfax, Université de Sfax, BP 1175, 3038, Sfax, Tunisia.
authors.forename: Boutheina
authors.initials: B
authors.lastname: Gargouri
authors.affiliation: Research and Development Functional Food Centre (CIDAF), Bioregión Building, Health Science Technological Park, Avda. del Conocimiento s/n, 18016, Granada, Spain. mmcontreras@ugr.es.|Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Avda. Fuentenueva s/n, 18071, Granada, Spain. mmcontreras@ugr.es.|Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba, 14071, Córdoba, Spain. mmcontreras@ugr.es.
authors.forename: María Del Mar
authors.initials: MD
authors.lastname: Contreras
authors.affiliation: Laboratoire d'Electrochimie et Environnement, Ecole Nationale d'Ingénieurs de Sfax, Université de Sfax, BP 1173, 3038, Sfax, Tunisia.
authors.forename: Sonda
authors.initials: S
authors.lastname: Ammar
authors.affiliation: Research and Development Functional Food Centre (CIDAF), Bioregión Building, Health Science Technological Park, Avda. del Conocimiento s/n, 18016, Granada, Spain.|Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Avda. Fuentenueva s/n, 18071, Granada, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Segura-Carretero
authors.affiliation: Laboratoire d'Electrochimie et Environnement, Ecole Nationale d'Ingénieurs de Sfax, Université de Sfax, BP 1173, 3038, Sfax, Tunisia.|Institut Supérieur de Biotechnologie de Sfax, Université de Sfax, BP 1175, 3038, Sfax, Tunisia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bouaziz
mesh_terms: D001673:Biodegradation, Environmental; D006838:Hydrocarbons / Q000378:metabolism; D010084:Oxidation-Reduction; D010578:Petroleum / Q000378:metabolism*; D020588:Stenotrophomonas / Q000378:metabolism*; D013501:Surface-Active Agents / Q000378:metabolism*; D013696:Temperature
chemical_list: D006838:Hydrocarbons; D010578:Petroleum; D013501:Surface-Active Agents
keywords: Bioremediation; Biosurfactant; Diketopiperazine; Emulsification; Stenotrophomonas sp.