Type 2 Quorum Sensing Monitoring, Inhibition and Biofilm Formation in Marine Microrganisms

Abstract

The quorum sensing (QS) dependent behaviour of micro-organisms, in particular expression of virulence genes, biofilm formation and dispersal, have provided impetus for investigating practical approaches to interfere with microbial QS. This study tests Halomonas pacifica and Marinobacter hydrocarbonoclasticus, two halophilic marine micro-organism, for their AI-2 dependent QS signalling and the effect of two well-known quorum-sensing inhibitors (QSIs), patulin and penicillic acid, on biofilm formation. We report, for the first time, the successful amplification of a putative luxS gene in H. pacifica using degenerated primers and AI-2 dependent QS as well as inhibition using QSIs. Penicillic acid had a strong inhibitory effect on AI-2 induction of H. pacifica at non-growth inhibitory concentrations, while patulin has an adverse effect only at the highest concentration (25 μM). QSIs effect on biofilm forming capability was isolate specific, with maximum inhibition at 25 μM of patulin in H. pacifica. In M. hydrocarbonoclasticus, no adverse effects were noted at any tested concentration of either QSIs. Detection of bioluminescence and the presence of a putative luxS gene provide biochemical and genetic evidence for the production of a signalling molecule(s) which is the essential first step in characterizing H. pacifica QS. This study highlights the importance of AI-2 dependent QS in a marine setting, not previously reported. It further suggests that QSI compounds must be selected in the specific system in which they are to function, and they cannot easily be transferred from one QS system to another.

Mining of luxS genes from rumen microbial consortia by metagenomic and metatranscriptomic approaches

“…Because previous studies indicated that AI-2-mediated QS is associated with biofilm formation in gut, oral, marine and brewery microbial communities (Kolenbrander et al 2010;Christiaen et al 2014;Liaqat et al 2014;Priha et al 2014), it is likely that many of the luxS genes collected in the present study, not only from R. albus but also from other bacteria, are probably involved in biofilm formation on feed particles for fiber degradation.…”

“…Ecological studies of rumen microbial communities showed that biofilm formation commences with the adhesion of initial colonizers, mainly cellulose-and starch-degrading bacteria, to the feed particles, and their end-products are used as substrates of other colonizers for developing biofilm (Minato & Suto 1976, 1978Cheng et al 1984;McAllister et al 1994). Because previous studies indicated that AI-2mediated QS is associated with biofilm formation in gut, oral, marine and brewery microbial communities (Kolenbrander et al 2010;Christiaen et al 2014;Liaqat et al 2014;Priha et al 2014), it is likely that many of the luxS genes collected in the present study, not only from R. albus but also from other bacteria, are probably involved in biofilm formation on feed particles for fiber degradation.…”

Antimicrobial Peptides in 2014

“…Importantly, a combined use of antimicrobial peptides with traditional antibiotics can be a more effective strategy to treat bacterial biofilms [ 180 , 181 , 182 ]. Finally, molecules that interfere with or even weaken the process of biofilm formation [ 183 , 184 , 185 , 186 , 187 , 188 , 189 ] can also be combined with antimicrobial peptides to achieve an optimal treatment of bacterial biofilms.…”

Evaluation of two autoinducer-2 quantification methods for application in marine environments

“…For example, Jahid et al (2015) found correlation between AI-2 secretion and biofilm formation by Aeromonas hydrophila in saline media. In a separate study, the application of an AI-2 inhibitor was found to reduce biofilm formation in marine strain Halomonas pacifica (Liaqat et al 2014) and mitigate membrane biofouling in seawater desalination RO system (Katebian et al 2016). Collectively, these studies imply the possibility of AI-2 related biofilm formation in marine environment.…”

“…In a separate study, the application of an AI‐2 inhibitor was found to reduce biofilm formation in marine strain Halomonas pacifica (Liaqat et al . ) and mitigate membrane biofouling in seawater desalination RO system (Katebian et al . ).…”