Antibiofilm activity substances derived from coral symbiotic bacterial extract inhibit biofouling by the model strainPseudomonas aeruginosaPAO1

Abstract

SummaryThe mitigation of biofouling has received significant research attention, with particular focus on non‐toxic and sustainable strategies. Here, we investigated quorum sensing inhibitor (QSI) bacteria as a means of controlling biofouling in a laboratory‐scale system. Approximately, 200 strains were isolated from coral (Pocillopora damicornis) and screened for their ability to inhibit quorum sensing (QS). Approximately, 15% of the isolates exhibited QSI activity, and a typical coral symbiotic bacterium, H12‐Vibrio alginolyticus, was selected in order for us to investigate quorum sensing inhibitory activity further. Confocal microscopy revealed that V. alginolyticus extract inhibited biofilm formation from Pseudomonas aeruginosa PAO1. In addition, the secondary metabolites of V. alginolyticus inhibited PAO1 virulence phenotypes by downregulating motility ability, elastase activity and rhamnolipid production. NMR and MS spectrometry suggested that the potential bioactive compound involved was rhodamine isothiocyanate. Quantitative real‐time PCR indicated that the bacterial extract induced a significant downregulation of QS regulatory genes (lasB, lasI, lasR, rhlI, rhlR) and virulence‐related genes (pqsA, pqsR). The possible mechanism underlying the action of rhodamine isothiocyanate analogue involves the disruption of the las and/or rhl system of PAO1. Our results highlight coral microbes as a bioresource pool for developing QS inhibitors and identifying novel antifouling agents.

<p>Quorum Quenching: A Potential Target for Antipseudomonal Therapy</p>

“…In addition, the Vibrio alginolyticus extract inhibits the production of biofilm in P. aeruginosa PAO1. 43 Moreover, some species of bacteria are capable of producing QQ enzymes that are as follows: (I) Firmicutes: Arthrobacter, Bacillus, and Oceanobacillus; (II) Actinobacteria: Rhodococcus and Streptomyces; (III) Proteobacteria: Acinetobacter, Agrobacterium tumefaciens, Alteromonas, Comomonas, Halomonas, Hyphomonas, Klebsiella pneumoniae, P. aeruginosa, Ralstonia, Stappia, and Variovorax paradoxus; (IV) Bacteroidetes: Tenacibaculum; and (V) Cyanobacteria: Anabaena. 14,[44][45][46][47][48][49] Prokaryotes have three types of enzymes that target the AHLs and play an essential role in QQ including AHL lactonases, AHL acylases, and AHL oxidoreductases.…”

The Rhodamine Isothiocyanate Analogue as a Quorum Sensing Inhibitor Has the Potential to Control Microbially-Induced Biofouling

“…The crude extracts and purified active compounds (rhodamine isothiocyanate analogue) from QSI strain Vibrio alginolyticus H12 were prepared as previously described [20]. To evaluate the anti-biofilm and antifouling properties of rhodamine isothiocyanate analogue, the bacterial cultures and purified active extracts (rhodamine isothiocyanate analogue) of strain H12 were mixed with sterilized agar, respectively, and encapsulated in a semipermeable membrane bag.…”

“…The biomass of the biofilm was quantified using crystal violet staining at each sampling time-point, as previously described [20]. Briefly, the membrane was incubated in 0.1% crystal violet (CV) solution for 30 min, washed, and then the CV was solubilized from the stained cells with 95% ethanol.…”

“…A 2-sufonylpyrimidine was demonstrated to effectively inhibit Pseudomonas aeruginosa biofilm formation [ 19 ]. We have also developed a new QSI (rhodamine isothiocyanate analogue), which demonstrates significant anti-biofilm ability on P. aeruginosa strain PAO1 under laboratory conditions [ 20 ]. However, most studies exploring the role of QSI have focused on the formation of single-species biofilm using a model bacterium (e.g., Staphylococcus aureus or Pseudomonas aeruginosa ) [ 16 , 21 ], and thus far there has been no study on natural biofilm formation involving complex communities.…”

“…In this study, following our previous work [ 20 ], we further investigated the anti-biofouling potential of rhodamine isothiocyanate analogue in the natural marine environment. We designed a series of semipermeable dialysis bags and hung them under the surface-water.…”