title: The biosurfactant viscosin transiently stimulates n-hexadecane mineralization by a bacterial consortium.
abstract: Pseudomonas produces powerful lipopeptide biosurfactants including viscosin, massetolide A, putisolvin, and amphisin, but their ability to stimulate alkane mineralization and their utility for bioremediation have received limited attention. The four Pseudomonas lipopeptides yielded emulsification indices on hexadecane of 20-31% at 90 mg/l, which is comparable to values for the synthetic surfactant Tween 80. Viscosin was the optimal emulsifier and significantly stimulated n-hexadecane mineralization by diesel-degrading bacterial consortia but exclusively during the first 2 days of batch culture experiments. Growth of the consortia, as determined by OD₆₀₀ measurements and quantification of the alkB marker gene for alkane degradation, was arrested after the first day of the experiment. In contrast, the control consortia continued to grow and reached higher OD₆₀₀ values and higher alkB copy numbers during the next days. Due to the short-lived stimulation of n-hexadecane mineralization, the stability of viscosin was analyzed, and it was observed that added viscosin was degraded by the bacterial consortium during the first 2 days. Hence, viscosin has a potential as stimulator of alkane degradation, but its utility in bioremediation may be limited by its rapid degradation and growth-inhibiting properties.
authors.affiliation: Section of Genetics and Microbiology, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg, Copenhagen, Denmark.
authors.forename: Frederik
authors.initials: F
authors.lastname: Bak
authors.forename: Lise
authors.initials: L
authors.lastname: Bonnichsen
authors.forename: Niels O G
authors.initials: NO
authors.lastname: Jørgensen
authors.forename: Mette H
authors.initials: MH
authors.lastname: Nicolaisen
authors.forename: Ole
authors.initials: O
authors.lastname: Nybroe
mesh_terms: D000473:Alkanes / Q000378:metabolism*; D001419:Bacteria / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental / Q000187:drug effects; D059013:Microbial Consortia; D010456:Peptides, Cyclic / Q000378:metabolism / Q000494:pharmacology*; D011549:Pseudomonas / Q000737:chemistry* / Q000378:metabolism; D012988:Soil Microbiology; D013501:Surface-Active Agents / Q000378:metabolism*
chemical_list: D000473:Alkanes; D010456:Peptides, Cyclic; D013501:Surface-Active Agents; C062796:viscosin; C007932:n-hexadecane