Presence of quorum-sensing inhibitor-like compounds from bacteria isolated from the brown algaColpomenia sinuosa

Abstract

Aims: Several Gram‐negative bacterial species use N‐acyl homoserine lactone (AHL) molecules as quorum‐sensing (QS) signals to regulate various biological functions. Similarly, various bacteria can stimulate, inhibit or inactivate QS signals in other bacteria by producing molecules called as quorum‐sensing inhibitors (QSI). Our aim was to screen and identify the epibiotic bacteria associated with brown algae for their ability of producing QS‐inhibiting activity. Methods and Results: QSI screenings were conducted on several epibiotic bacteria isolated from a marine brown alga Colpomenia sinuosa, using Serratia rubidaea JCM 14263 as an indicator organism. Strain JCM 14263 controls the production of red pigment, prodigiosin by AHL QS. Out of 96 bacteria, which were isolated from the surface of the brown alga, 12% of strains showed the ability to produce QSI, which was observed from the pigmentation inhibition on Ser. rubidaea JCM 14263 without affecting its growth. Phylogenetic analysis using 16S rRNA gene sequencing method demonstrated bacterial isolates showing QS inhibition‐producing bacteria belonging to the Bacillaceae (Firmicutes), Pseudomonadaceae (Proteobacteria), Pseudoalteromonadaceae (Proteobacteria) and Vibrionaceae (Proteobacteria). Conclusion: An appreciable percentage of bacteria isolated from the brown alga produced QSI‐like compounds. Significance and Impact of the Study: The screening method using Ser. rubidaea described in this report will facilitate the rapid identification of QSI‐producing bacteria from marine environment. This study reveals new avenue for future environmental applications. This study also suggests that these algal epibiotic bacteria may play a role in the defensive mechanism for their host by producing QSI or QSI‐like compounds to suppress the settlement of other competitive bacteria.

Serratia Infections: from Military Experiments to Current Practice

“…Also, S. liquefaciens, S. plymuthica, and S. rubidaea were associated with the rhizosphere of oilseed rape, and all three demonstrated antifungal properties (208). In addition, S. rubidaea was found associated with marine alga in one study (209).…”

Intimate Associations Between Epiphytes, Endophytes, and Parasites of Seaweeds

“…In addition to the furanones of D. pulchra, a variety of bacteria and eukaryotes have been shown to produce cyclic dipeptides that can act as AHL mimics and affect QS-regulated behavior in other bacteria (Dobretsov et al 2009;Dickschat 2010). Recently, Kanagasabhapathy et al (2009) suggested that certain epibiotic bacteria from the brown macroalga Colpomenia sinuosa may play a role in defense mechanisms and suppress the settlement of other competitive bacteria by producing quorum sensing inhibitors (QSI) or QSI-like compounds.…”

“…During the past decade it has been shown that various macroalgae are able to stimulate, inhibit, or inactivate QS signals in bacteria by producing QS inhibitors or analogs thereof (Maximilien et al 1998;Joint et al 2007;Kanagasabhapathy et al 2009). The Australian red macroalga Delisea pulchra produces halogenated furanones, structural analogs to N-acyl homoserine lactones.…”

Exploiting Quorum Sensing To Confuse Bacterial Pathogens

“…Aquatic ecosystems continue to reveal diverse microorganism taxonomies and to yield enormous diversity in secondary metabolite products. Numerous reports are emerging that provide empirical data demonstrating QSI activity from various marine sources that include sponges (290), microalgae (291), bryozoa (292), and alga-and coral-associated bacteria (293,294). Low-micromolar concentrations of phenethylamide compounds from the marine bacterium Halobacillus salinus were found to inhibit V. harveyi luminescence and C. violaceum pigment production without inhibiting growth (295).…”