The hydrocarbon‐degrading marine bacteriumCobetiasp. strainMM1IDA2H‐1 produces a biosurfactant that interferes with quorum sensing of fish pathogens by signal hijacking

Abstract

SummaryBiosurfactants are produced by hydrocarbon-degrading marine bacteria in response to the presence of water-insoluble hydrocarbons. This is believed to facilitate the uptake of hydrocarbons by bacteria. However, these diffusible amphiphilic surface-active molecules are involved in several other biological functions such as microbial competition and intra-or inter-species communication. We report the isolation and characterization of a marine bacterial strain identified as Cobetia sp. MM1IDA2H-1, which can grow using the sulfur-containing heterocyclic aromatic hydrocarbon dibenzothiophene (DBT). As with DBT, when the isolated strain is grown in the presence of a microbial competitor, it produces a biosurfactant. Because the obtained biosurfactant was formed by hydroxy fatty acids and extracellular lipidic structures were observed during bacterial growth, we investigated whether the biosurfactant at its critical micelle concentration can interfere with bacterial communication systems such as quorum sensing. We focused on Aeromonas salmonicida subsp. salmonicida, a fish pathogen whose virulence relies on quorum sensing signals. Using biosensors for quorum sensing based on Chromobacterium violaceum and Vibrio anguillarum, we showed that when the purified biosurfactant was mixed with N-acyl homoserine lactones produced by A. salmonicida, quorum sensing was inhibited, although bacterial growth was not affected. In addition, the transcriptional activities of A. salmonicida virulence genes that are controlled by quorum sensing were repressed by both the purified biosurfactant and the growth in the presence of Cobetia sp. MM1IDA2H-1. We propose that the biosurfactant, or the lipid structures interact with the N-acyl homoserine lactones, inhibiting their function. This could be used as a strategy to interfere with the quorum sensing systems of bacterial fish pathogens, which represents an attractive alternative to classical antimicrobial therapies in fish aquaculture.

Biosurfactant production from marine hydrocarbon-degrading consortia and pure bacterial strains using crude oil as carbon source

“…That specific strain is very well described in the literature ( Yakimov et al, 1998 ; Golyshin et al, 2003 ; Schneiker et al, 2006 ) and it is one of the major players in hydrocarbon degradation in the water column; being commonly found in enrichment cultures and contaminated areas ( Yakimov et al, 1998 ; Golyshin et al, 2003 ; Schneiker et al, 2006 ). Members of the Rhodobacteraceae, Rhodospirillaceae, Halomonadaceae, Oceanospirillaceae, Pseudomonadaceae, and Shewanellaceae families have also been reported to encompass oil-degraders and BS producers ( Cui et al, 2008 ; Fredrickson et al, 2008 ; Mnif et al, 2009 ; Raaijmakers et al, 2010 ; Jiménez et al, 2011 ; Kostka et al, 2011 ; Ibacache-Quiroga et al, 2013 ). However, the single strains isolated from these families in this study did not show significant BS production (drop collapse test).…”

Going Green and Cold: Biosurfactants from Low-Temperature Environments to Biotechnology Applications

“…The type strain SK-2, isolated from North Sea sediment, can grow exclusively on hydrocarbons in a temperature range of [ 3 0 6 _ T D $ D I F F ] 4-35 C while producing a well-characterized glucose-lipid biosurfactant [26,27]. Since then various other marine bacteria, typically Pseudomonas, Pseudoalteromonas, Marinomonas, Halomonas, Rhodococcus, and Cobetia have been described as biosurfactant producers from the polar oceans, deep sea, and marine sediments [28][29][30][31][32]. Kurata and colleagues [33] developed a novel approach, based on satellite remote sensing, to identify slicks of biosurfactants through their effect of surface tension reduction on the appearance of the sea surface, and demonstrated the involvement of microbial biosurfactants in the uptake of hydrophobic substances in the marine environment.…”

Sharply Reduced Biofilm Formation from Cobetia marina and in Black Sea Water on Modified Siloxane Coatings

“…It is known, for example, that C. marina strain KMM MC-296 produces an alkaline phosphatase with a very high specific activity (15,000 DE U/1 mg of protein) [43], the Cobetia sp. strain MM1IDA2H-1 produces a bio-surfactant that interferes with the quorum sensing of fish pathogens by signal hijacking [44], and the C. marina DSMZ 4741 strain synthesizes an unexpected K-antigen-like exopolysaccharide [45]. Therefore, the explanation of the mechanism of C. marina attachment and biofilm formation on modified siloxane coatings with different composition and surface characteristics is difficult.…”