Identification and characterisation of short chain rhamnolipid production in a previously uninvestigated, non-pathogenic marine pseudomonad

Matthew S. Twigg, L. Tripathi, A. Zompra, Karina Salek, V. U. Irorere, T. Gutierrez, G. A. Spyroulias, R. Marchant, Ibrahim M. Banat

Research output: Contribution to journalArticle

7 Citations (Scopus)
42 Downloads (Pure)

Abstract

This study aimed to identify and characterise biosurfactant compounds produced by bacteria associated with a marine eukaryotic phytoplankton bloom. One strain, designated MCTG214(3b1), was isolated by enrichment with polycyclic aromatic hydrocarbons and based on 16S rDNA, and gyrB sequencing was found to belong to the genus Pseudomonas, however not related to P. aeruginosa. Cell-free supernatant samples of strain MCTG214(3b1) at stationary phase showed significant reductions in surface tension. HPLC-MS and NMR analysis of these samples indicated the presence of five different rhamnolipid (RL) congeners. Di-rhamnolipids accounted for 87% relative abundance and all congeners possessed fatty acid moieties consisting of 8–12 carbons. PCR screening of strain MCTG214(3b1) DNA revealed homologues to the P. aeruginosa RL synthesis genes rhlA and rhlB; however, no rhlC homologue was identified. Using the Galleria mellonella larvae model, strain MCTG214(3b1) was demonstrated to be far less pathogenic than P. aeruginosa. This study identifies for the first time a significantly high level of synthesis of short chain di-rhamnolipids by a non-pathogenic marine Pseudomonas species. We postulate that RL synthesis in Pseudomonas sp. MCTG214(3b1) is carried out by enzymes expressed from rhlA/B homologues similar to those of P. aeruginosa; however, a lack of rhlC potentially indicates the presence of a second novel rhamnosyltransferase responsible for the di-rhamnolipid congeners identified by HPLC-MS.

Original languageEnglish
Pages (from-to)1-13
Number of pages13
JournalApplied Microbiology and Biotechnology
Early online date10 Jul 2018
DOIs
Publication statusE-pub ahead of print - 10 Jul 2018

Keywords

  • Biosurfactant
  • Marine bacteria
  • Non-pathogenic
  • Pseudomonas
  • Rhamnolipid

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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