Production of N-acyl Homoserine Lactones and Virulence Factors of Waterborne Aeromonas hydrophila

Abstract

Aeromonads are inhabitants of aquatic ecosystems and are described as being involved in intestinal disturbances and other infections. The purpose of this study was to investigate the production of N-acyl-homoserine lactone (AHL) signal molecules and some virulence factors, including hemolysins, proteases, extracellular nucleases production and cytotoxicity by waterborne Aeromonas hydrophila. A total of 24 strains isolated from fresh-water or diseased fish were used in the study. The majority A.hydrophila strains produce two AHL molecules (21/24), one is N-butanoyl homoserine lactone (BHL), and the other is N-hexanoyl homoserine lactone (HHL) according to thin-layer chromatography analysis. Among the virulence factors tested, more than 83 % of the isolates produced β haemolysin when inoculated on sheep blood agar, only 50 % of the isolates displayed DNase activity, 75 % of the isolates shown proteolytic activity on skimmed milk plate, and cytotoxic activity was detected in 20 of 24 of the isolates. The strains producing AHLs possessed one or more virulence factors. In conclusion, the production of quorum sensing signal molecules is common among the strains that we examined, and there seems to some relationships between quorum sensing signal production and virulence factors in A. hydrophila.

The Social Life of Aeromonas through Biofilm and Quorum Sensing Systems

“…In another study, all clinical tested strains of A. hydrophila ( n = 20) and Aeromonas sobria ( n = 2) produced either C4-HSL and C6-HSL or both, including 10 strains that produced an additional AHL, a putative N-pentanoyl homoserine lactone (C5-HSL; Chan et al, 2011). Other studies showed similar results, e.g., A. caviae YL12 (Table 3), although additional AHLs were not systematically characterized (Bruhn et al, 2005; Morgan-Sagastume et al, 2005; Medina-Martínez et al, 2006; Schwenteit et al, 2011; Chong et al, 2012; Huang et al, 2012; Chu et al, 2013; Ochiai et al, 2013; Lim et al, 2014; Zeng et al, 2014). The HPLC data confirmed results obtained with bioassays (Table 3).…”

Evolution of Resistance to Quorum-Sensing Inhibitors

“…A set of criteria has been laid down for identifying QSI molecules: (i) a low molecular mass, (ii) highly specific, (iii) stable and resistant to hydrolytic enzymes of the host (iv) no adverse effect on the host, (v) longer side chain than the native AHLs [32–34]. QSIs have been shown to be produced by plants, animals, bacteria, and other microbes [25, 26, 28, 35, 36]. The apprehension is that constant and indiscriminate usage of QSIs may put bacteria under pressure to develop means to evade this treatment procedure.…”

Antibiofilm Activity of Biosurfactant Producing Coral Associated Bacteria Isolated from Gulf of Mannar

“…Continuous and indiscriminate usage of antibiotics have paved way for the development of antibiotic resistant bacteria and few which were resistant to multiple antibiotics. Antibiotics have become ineffective in controlling the virulence of bacterial pathogens [11][12][13][14][15]. Hence, novel antimicrobial agents which selectively reduce the virulence of pathogens rather than inducing antimicrobial resistance are the need of the hour [16].…”