Uncovering behavioural diversity amongst high-strength Pseudomonas spp. surfactants at the limit of liquid surface tension reduction

Kamaluddeen Kabir, Yusuf Y. Deeni, Simona Hapca, Luke Moore, Andrew J. Spiers

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2 Citations (Scopus)
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Bacterial biosurfactants have a wide range of biological functions and biotechnological applications. Previous analyses had suggested a limit to their reduction of aqueous liquid surface tensions (γ Min), and here we confirm this in an analysis of 25 Pseudomonas spp. strains isolated from soil which produce high-strength surfactants that reduce surface tensions to 25.2 ± 0.1-26.5 ± 0.2 mN m -1 (the surface tension of sterile growth medium and pure water was 52.9 ± 0.4 mN m-1 and 72.1 ± 1.2 mN m -1, respectively). Comparisons of culture supernatants produced using different growth media and semi-purified samples indicate that the limit of 24.2-24.7 mN m -1 is not greatly influenced by culture conditions, pH or NaCl concentrations. We have used foam, emulsion and oil-displacement behavioural assays as a simple and cost-effective proxy for in-depth biochemical characterisation, and these suggest that there is significant structural diversity amongst these surfactants that may reflect different biological functions and offer new biotechnological opportunities. Finally, we obtained a draft genome for the strain producing the highest strength surfactant, and identified a cluster of non-ribosomal protein synthase genes that may produce a cyclic lipopeptide (CLP)-like surfactant. Further investigation of this group of related bacteria recovered from the same site will allow a better understanding of the significance of the great variety of surfactants produced by bacterial communities found in soil and elsewhere.

Original languageEnglish
Article numberfny008
Pages (from-to)1-7
Number of pages7
JournalFEMS Microbiology Letters
Issue number4
Early online date16 Jan 2018
Publication statusPublished - Feb 2018


  • Cyclic lipopeptide
  • Limit to liquid surface activity
  • Non-ribosomal protein synthase
  • Pseudomonas
  • Surfactant


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