LuxS/AI-2 Quorum Sensing System in Edwardsiella piscicida Promotes Biofilm Formation and Pathogenicity

Abstract

LuxS/AI-2 is an important quorum sensing system which affects the growth, biofilm formation, virulence, and metabolism of bacteria. LuxS is encoded by the luxS gene, but how this gene is associated with a diverse array of physiological activities in Edwardsiella piscicida (E. piscicida) is not known. Here, we constructed an luxS gene mutant strain, the △luxS strain, to identify how LuxS/AI-2 affects pathogenicity. The results showed that LuxS was not found in the luxS gene mutant strain, and this gene deletion decreased E. piscicida growth compared to that of the wild-type strain. Meanwhile, the wild-type strain significantly increased penetration and motility in mucin compared to levels with the △luxS strain. The 50% lethal dose (LD50) of the E. piscicida △luxS strain for zebrafish was significantly higher than that of the wild-type strain, which suggested that the luxS gene deletion could attenuate the strain’s virulence. The AI-2 activities of EIB202 were 56-fold higher than those in the △luxS strain, suggesting that the luxS gene promotes AI-2 production. Transcriptome results demonstrated that between cells infected with the △luxS strain and those infected with the wild-type strain 46 genes were significantly differentially regulated, which included 34 upregulated genes and 12 downregulated genes. Among these genes, the largest number were closely related to cell immunity and signaling systems. In addition, the biofilm formation ability of EIB202 was significantly higher than that of the △luxS strain. The supernatant of EIB202 increased the biofilm formation ability of the △luxS strain, which suggested that the luxS gene and its product LuxS enhanced biofilm formation in E. piscicida. All results indicate that the LuxS/AI-2 quorum sensing system in E. piscicida promotes its pathogenicity through increasing a diverse array of physiological activities.

Correlation Between Antimicrobial Resistance and Biofilm Formation Capability Among Klebsiella Pneumoniae Strains Isolated From Hospitalized Patients in Iran

“…Notably, in our study the luxS gene was detected in about 98% of the tested isolates. Using a rat model of middle ear challenge, Yadav et al (2018) demonstrated that the functional defect in LuxS, leading to the reduced colonization capability of pneumococci in vivo [29]. However, in contrast to our results, Pakhshan et al [30] concluded that the susceptible isolates to antibiotics tend to form stronger bio lms compared with the resistant strains.…”

Correlation between antimicrobial resistance and biofilm formation capability among Klebsiella pneumoniae strains isolated from hospitalized patients in Iran

“…Notably, in our study the luxS gene was detected in about 98 % of the tested isolates. Using a rat model of middle ear challenge, Yadav et al demonstrated that a functional defect in LuxS, leading to the reduced colonization capability of pneumococci in vivo [28]. Our results exhibited that resistance to antimicrobial agents was higher in K. pneumoniae which is biofilm producer than non-biofilm producer.…”

Monitoring the Starvation–Survival Response of Edwardsiella piscicida and E. tarda in Freshwater Microcosms, at Various Temperatures

“…A recent paper introduced that Edwardsiella exist in aquatic environments either as individual planktonic cells or in communal biofilms [ 31 ]. However, biofilm production by Edwardsiella has been only related to its life as a pathogen for vertebrate animals [ 32 , 33 ]. Moreover, E. piscicida and E. tarda have hardly been isolated from surface water in natural environments, and work on this subject is limited.…”