title: Effect of biosurfactants on Pseudomonas aeruginosa and Staphylococcus aureus biofilms in a BioFlux channel.
abstract: Recent studies have indicated that biosurfactants play a role both in maintaining channels between multicellular structures in biofilms and in dispersal of cells from biofilms. A combination of caprylic acid (0.01 % v/v) together with rhamnolipids (0.04 % v/v) was applied to biofilms of Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 9144 and a mixed culture under BioFlux flowthrough conditions and caused disruption of the biofilms. The biofilms were also treated with a combination of rhamnolipids (0.04 % v/v) and sophorolipids (0.01 %). Control treatments with PBS 1× had no apparent effect on biofilm disruption. The Gram-positive bacterium (S. aureus ATCC 9144) was more sensitive than P. aeruginosa ATCC 15442 in terms of disruption and viability as shown by Live/Dead staining. Disruption of biofilms of P. aeruginosa ATCC 15442 was minimal. Oxygen consumption by biofilms, after different treatments with biosurfactants, confirms that sophorolipid on its own is unable to kill/inhibit cells of P. aeruginosa ATCC 15442, and even when used in combination with rhamnolipids, under static conditions, no decrease in the cell viability was observed. Cells in biofilms exposed to mono-rhamnolipids (0.04 % v/v) showed behaviour typical of exposure to bacteriostatic compounds, but when exposed to di-rhamnolipids (0.04 % v/v), they displayed a pattern characteristic of bactericidal compounds.
authors.affiliation: School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, M13 9PL, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Diaz De Rienzo
authors.affiliation: Unilever Research and Development Laboratory, Port Sunlight, Wirral, CH62 4ZD, UK.
authors.forename: P S
authors.initials: PS
authors.lastname: Stevenson
authors.affiliation: School of Biomedical Sciences, Faculty of Life and Health Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: R
authors.initials: R
authors.lastname: Marchant
authors.affiliation: School of Biomedical Sciences, Faculty of Life and Health Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK. IM.Banat@ulster.ac.uk.
authors.forename: I M
authors.initials: IM
authors.lastname: Banat
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002210:Caprylates / Q000032:analysis / Q000494:pharmacology; D006017:Glycolipids / Q000032:analysis / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D013501:Surface-Active Agents / Q000032:analysis / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D002210:Caprylates; D006017:Glycolipids; D013501:Surface-Active Agents; C418382:rhamnolipid; C031492:octanoic acid
keywords: BioFlux; Biofilms; Biosurfactants; Rhamnolipids
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