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

TY - JOUR

T1 - Uncovering behavioural diversity amongst high-strength Pseudomonas spp. surfactants at the limit of liquid surface tension reduction

AU - Kabir, Kamaluddeen

AU - Deeni, Yusuf Y.

AU - Hapca, Simona

AU - Moore, Luke

AU - Spiers, Andrew J.

N1 - We acknowledge the funding Kamaluddeen Kabir received from Umaru Musa Yar’adua University and TETFUND Nigeria. Andrew Spiers is also member of the Scottish Alliance for Geoscience, Environment and Society (SAGES).

PY - 2018/2

Y1 - 2018/2

N2 - 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.

AB - 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.

KW - Cyclic lipopeptide

KW - Limit to liquid surface activity

KW - Non-ribosomal protein synthase

KW - Pseudomonas

KW - Surfactant

UR - https://www.scopus.com/pages/publications/85045648771

U2 - 10.1093/femsle/fny008

DO - 10.1093/femsle/fny008

M3 - Article

C2 - 29346641

SN - 0378-1097

VL - 365

SP - 1

EP - 7

JO - FEMS Microbiology Letters

JF - FEMS Microbiology Letters

IS - 4

M1 - fny008

ER -