Influence of Glucose Concentrations on Biofilm Formation, Motility, Exoprotease Production, and Quorum Sensing in Aeromonas hydrophila

Abstract

Aeromonas hydrophila recently has received increased attention because it is opportunistic and a primary human pathogen. A. hydrophila biofilm formation and its control are a major concern for food safety because biofilms are related to virulence. Therefore, we investigated biofilm formation, motility inhibition, quorum sensing, and exoprotease production of this opportunistic pathogen in response to various glucose concentrations from 0.05 to 2.5% (wt/vol). More than 0.05% glucose significantly impaired (P < 0.05) quorum sensing, biofilm formation, protease production, and swarming and swimming motility, whereas bacteria treated with 0.05% glucose had activity similar to that of the control (0% glucose). A stage shift biofilm assay revealed that the addition of glucose (2.5%) inhibited initial biofilm formation but not later stages. However, addition of quorum sensing molecules N-3-butanoyl-DL-homoserine lactone and N-3-hexanoyl homoserine lactone partially restored protease production, indicating that quorum sensing is controlled by glucose concentrations. Thus, glucose present in food or added as a preservative could regulate acyl-homoserine lactone quorum sensing molecules, which mediate biofilm formation and virulence in A. hydrophila.

N-Acetylglucosamine Inhibits LuxR, LasR and CviR Based Quorum Sensing Regulated Gene Expression Levels

“…Other mechanisms that regulate transcription of genes influenced by LuxR type regulatory proteins include CRP, GroESL and Hnr (Shrout et al, 2006; Jahid et al, 2013). Results presented here suggest that NAG inhibits transcription of genes upregulated by AHL binding to LuxR, LasR and CviR based QS systems.…”

“…The role of CRP in regulating carbon metabolism through carbon catabolite repression of E. coli and B. subtilis has been well characterized (Gorke and Stulke, 2008) but as mentioned above CRP also influences transcription of AHL dependent genes by binding to the same promoters of LuxR type proteins (Dunlap and Greenberg, 1988; Albus et al, 1997; Liang et al, 2007). Certainly, nutritional conditions have been shown to affect expression of QS regulated phenotypes (Shrout et al, 2006; Jahid et al, 2013). Assay inhibition by glucose and glucosamine presented here shows that the influence of catabolite repression is strain specific.…”

“…It has been reported that specific carbon sources mediate QS activity and swarming motility in P. aeruginosa biofilm formation (Shrout et al, 2006). Similarly, glucose treated Aeromonas hydrophila cultures downregulate QS regulated phenomena such as biofilm formation and virulence (Jahid et al, 2013). On the other hand, starvation regulates QS signaling and represses cell growth in P. aeruginosa and Bacillus subtilis which triggers entry into the stationary phase (You et al, 1998; Lazazzera et al, 1999).…”

Inhibitory effects of single-walled carbon nanotubes on biofilm formation fromBacillus anthracisspores

“…Other bacterial species, such as Aeromonas hydrophila KCTC 11533, also showed a similar resistance trend to antimicrobial agents. When A. hydrophila biofilm was treated with 2.5% glucose at different stages, biofilm formation was decreased by 89.9, 83.3, 67.4, 50.1, and 18.4% at glucose adding times of 0 h, 6 h, 12 h, one day, and two days, respectively, during the six-day incubation at 30°C (Jahid et al 2013).…”

The Social Life of Aeromonas through Biofilm and Quorum Sensing Systems

“…The substratum properties, chemical components, and nutrient availability are critical conditions influencing bacterial attachment. For instance, Jahid et al (2013, 2015) have shown that low salinity (0.25% wt./vol.) enhances biofilm formation by Aeromonas hydrophila , whereas glucose concentration above 0.05% (wt./vol.)…”