Quorum quenching in cultivable bacteria from dense marine coastal microbial communities

Abstract

Acylhomoserine lactone (AHLs)-mediated quorum-sensing (QS) processes seem to be common in the marine environment and among marine pathogenic bacteria, but no data are available on the prevalence of bacteria capable of interfering with QS in the sea, a process that has been generally termed 'quorum quenching' (QQ). One hundred and sixty-six strains isolated from different marine dense microbial communities were screened for their ability to interfere with AHL activity. Twenty-four strains (14.4%) were able to eliminate or significantly reduce N-hexanoyl-l-homoserine lactone activity as detected by the biosensor strain Chromobacterium violaceum CV026, a much higher percentage than that reported for soil isolates, which reinforces the ecological role of QS and QQ in the marine environment. Among these, 15 strains were also able to inhibit N-decanoyl-l-homoserine lactone activity and all of them were confirmed to enzymatically inactivate the AHL signals by HPLC-MS. Active isolates belonged to nine different genera of prevalently or exclusively marine origin, including members of the Alpha- and Gammaproteobacteria (8), Actinobacteria (2), Firmicutes (4) and Bacteroidetes (1). Whether the high frequency and diversity of cultivable bacteria with QQ activity found in near-shore marine isolates reflects their prevalence among pelagic marine bacterial communities deserves further investigation in order to understand the ecological importance of AHL-mediated QS and QQ processes in the marine environment.

Inhibition ofSteptococcus mutansbiofilm formation by extracts ofTenacibaculumsp. 20J, a bacterium with wide-spectrum quorum quenching activity

“…Biofilm formation by S. mutans was also assessed in BHI supplemented with both sucrose and glucose at 0.1% and 0.2%. The strain Tenacibaculum sp.20J CECT7426, isolated in our laboratory from a marine sample [29], and T. maritimum NCIMB2154 T were routinely cultured at 22°C on Marine Agar/Broth pH 7.0 (MA/MB, Difco).…”

Antibiofilm activity substances derived from coral symbiotic bacterial extract inhibit biofouling by the model strain Pseudomonas aeruginosa PAO1

“…In our present study, we found that 15% of coral‐associated bacteria exhibited inhibition activity against C. violaceum 12472. Previous studies reported that approximately 11–24% of the coral‐associated bacteria sampled were capable of QS inhibition activity against E. coli pSB1075, C. violaceum CV026 and A. tumefaciens KYC55 indicator strains (Romero et al ., 2011; Karina et al ., 2013). Our results are in line with these proportions and further suggest that coral ecosystems represent an ideal reservoir from which to develop QSI products.…”

Identification of a Pseudomonas sp. that Inhibits RHL System of Quorum Sensing

“…The pyocyanin assay [12] is based on its absorbance at 520 nm. Protease activity was measured using the azocasein method [10]. Elastase activity was assessed using elastin-congo red as described [13].…”

“…In contrast, a few studies, to our knowledge, have devoted to the isolation anti-QS compounds from soil bacteria [10]. The goal of the present study was to attempt to isolate new and perhaps more powerful QS inhibitors from soil bacteria using a new QSI screening system.…”