Isolation and characterization of two new lipopeptide biosurfactants produced
by Pseudomonas fluorescens BD5 isolated from water from the Arctic Archipelago
of Svalbard
The arctic freshwater bacterium Pseudomonas fluorescens BD5 produces biosurfactants when grown on 2%
glucose. Crude biosurfactants were extracted from a cell-free culture supernatant with ethyl acetate and
purified by preparative reversed phase high performance liquid chromatography (RP-HPLC). The chemical
structure of the purified biosurfactants, pseudofactin I and II, was analyzed by matrix assisted laser
desorption/ionization time of flight (MALDI TOF) mass spectrometry and tandem mass spectrometry
(MS/MS). Both compounds are novel cyclic lipopeptides with a palmitic acid connected to the terminal
amino group of eighth amino acid in peptide moiety. The C-terminal carboxylic group of the last amino
acid (Val or Leu) forms a lactone with the hydroxyl of Thr3. Pseudofactin II reduced the surface tension of
water from 72 mN/m to 31.5 mN/m at a concentration of 72 mg/l. Its emulsification activity and stability
was greater than that of the synthetic surfactants Tween 20 and Triton X-100; pseudofactins thus have a
great potential for application in industrial fields such as bioremediation or biomedicine.
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