Lipids of Dietzia sp. A14101. Part II: A study of the dynamics of the release of surface active compounds by Dietzia sp. A14101 into the medium. (November 2017)

• Record Type: Journal Article
• Authors: Hvidsten, Ina; Mjøs, Svein Are.; Bødtker, Gunhild; Barth, Tanja
• Is Part Of: Chemistry and physics of lipids. Volume 208(2017)
• Page Start: 31
• Page End: 42
• Publication Date: 2017-11
• Subjects: BS biosurfactant -- BE bioemulsifier -- CFA cyclopropane FA -- ECL equivalent chain length index -- EOR enhanced oil recovery -- Fame fatty acid methyl ester -- FA fatty acid -- Gly glycolipid -- G.R.A.S. generally regarded as safe -- HC hydrocarbon -- I incubation -- LLE liquid–liquid extraction -- LCFA long-chain FA -- MUFA mono-unsaturated FA -- L lyophilised -- PL lhospholipid -- SAT-FA saturated -- SCMA short-chain mycolic acid -- S sampling; Genus Dietzia -- Bacterial lipids -- Bio-surfactants -- Hydrocarbon-degradation -- Cell-bound -- Bio-surfactant-producing bacterial strain -- Gram-positive bacteria; Lipids -- Periodicals; Lipids -- Periodicals; Lipides -- Périodiques; Lipids; Periodicals; Electronic journals; 547.77
• DOI: 10.1016/j.chemphyslip.2017.08.007
• Languages: English
• ISSNs: 0009-3084

Abstract

Highlights: Dietzia sp. A 14101 secretes small amounts of glycolipids into the medium. Surface activity of the secreted metabolite mixture is low. Both acidic and neutral glycolipids are secreted; secretion of latter is growth- associated. Intact bacterial cells should be used for EOR and bioremediation applications. Abstract: Dietzia sp. A14101 isolated from an oil reservoir model column was found to induce a strong decrease of the interfacial tension (IFT) in hydrocarbon-water mixtures in the presence of the intact bacterial cells (Kowalewski et al., 2005). The strain was shown to be able to degrade a wide range of hydrocarbon substrates (Bødtker et al., 2009). Further studies showed that the surface-active compounds tentatively identified as glycolipids were produced by Dietzia sp. A14101 on non- and water-immiscibl e –hydrocarbon substrates, Part I (Hvidsten et al., 2017). The results suggested that biosurfactant (BS) was a mixture of several isomers. The study presented here is aimed to investigate whether BS are secreted into the aqueous medium, and if so, then at which phase of the culture growth and in which amounts – the dynamics of the BS release in incubations on water-immiscible hydrocarbons. Two methods of BS extraction from the medium were attempted and compared: a liquid–liquid extraction (LLE) and precipitation by acid. For qualitative and semi-quantitative assessment, gas chromatography-mass spectrometry (GC/MS), thin-layer chromatography (TLC), liquid chromatography-mass spectrometry (LC–MS), surface tension measurements (SFT), emulsification (E24 ) and oil-spreading tests were employed. The results indicated that BS only partially were secreted into the medium. Detectable amounts of glycolipids in media were first identified during the exponential growth phase. However, only a slight decrease of SFT was observed in the cell-free medium. The emulsification index values of the sampled material were lower than those reported for related strains. The results suggested that most of the BS produced by Dietzia sp. A14101 remains cell-bound during the culture development in a batch mode and only a narrow range of the BS isomers can be detected in small amounts in media.