title: Production and characterization of a trehalolipid biosurfactant produced by the novel marine bacterium Rhodococcus sp., strain PML026.
abstract: OBJECTIVE
  The aim of this study was to evaluate biosurfactant production by a novel marine Rhodococcus sp., strain PML026 and characterize the chemical nature and properties of the biosurfactant.
  
  
  RESULTS
  A novel marine bacterium (Rhodococcus species; strain PML026) was shown to produce biosurfactant in the presence of hydrophobic substrate (sunflower oil). Biosurfactant production (identified as a trehalolipid) was monitored in whole-batch cultures (oil layer and aqueous phase), aqueous phase (no oil layer) and filtered (0·2 μm) aqueous phase (no oil or cells; extracellular) and was shown to be closely associated with growth/biomass production. Extracellular trehalolipid levels increased postonset of stationary growth phase. Purified trehalolipid was able to reduce the surface tension of water to 29 mN m(-1) at Critical Micellar Concentration (CMC) of c. 250 mg l(-1) and produced emulsions that were stable to a wide range of conditions (pH 2-10, temperatures of 20-100°C and NaCl concentrations of 5-25% w/v). Separate chemical analyses of the intact trehalolipid and its constituents demonstrated the compound was in fact a mixture of homologues (>1180 MW) consisting of a trehalose moiety esterified to a series of straight chain and hydroxylated fatty acids.
  
  
  CONCLUSIONS
  The trehalolipid biosurfactant produced by the novel marine strain Rhodococcus sp. PML026 was characterized and exhibited high surfactant activity under a wide range of conditions.
  
  
  CONCLUSIONS
  Strain PML026 of Rhodococcus sp. is a potential candidate for bioremediation or biosurfactant production for various applications.
authors.affiliation: Plymouth Marine Laboratory, Plymouth, Devon, UK. dani@pml.ac.uk
authors.forename: D A
authors.initials: DA
authors.lastname: White
authors.forename: L C
authors.initials: LC
authors.lastname: Hird
authors.forename: S T
authors.initials: ST
authors.lastname: Ali
mesh_terms: D001673:Biodegradation, Environmental; D004655:Emulsions; D006017:Glycolipids / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008823:Micelles; D012240:Rhodococcus / Q000254:growth & development / Q000378:metabolism*; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013696:Temperature; D014199:Trehalose / Q000032:analysis
chemical_list: D004655:Emulsions; D006017:Glycolipids; D008823:Micelles; D013501:Surface-Active Agents; D014199:Trehalose
keywords: Rhodococcus; biosurfactant; glycolipid; marine; trehalolipid