Abstract
Quorum quenching (QQ) is a promising alternative infection-control strategy to antibiotics that controls quorum-regulated virulence without killing the pathogens. Aeromonas hydrophila is an opportunistic gram-negative pathogen living in freshwater and marine environments. A. hydrophila possesses an N-acyl homoserine lactone (AHL)-based quorum-sensing (QS) system that regulates virulence, so quorum signal-inactivation (i.e., QQ) may represent a new way to combat A. hydrophila infection. In this study, an AHL lactonase gene, aiiA was cloned from Bacillus sp. strain QSI-1 and expressed in Escherichia coli strain BL21(DE3). The A. hydrophila hexanoyl homoserine lactone (C6-HSL) QS signal molecule was degraded by AiiAQSI-1, which resulted in a decrease of bacterial swimming motility, reduction of extracellular protease and hemolysin virulence factors, and inhibited the biofilm formation of A. hydrophila YJ-1 in a microtiter assay. In cell culture studies, AiiAQSI-1 decreased the ability of A. hydrophila adherence to and internalization by Epithelioma papulosum cyprini (EPC) cells. During in vivo studies, oral administration of AiiAQSI-1 via feed supplementation attenuated A. hydrophila infection in Crucian Carp. Results from this work indicate that feed supplementation with AiiAQSI-1 protein has potential to control A. hydrophila aquaculture disease via QQ.
Highlights
Quorum sensing (QS) is a cell-to-cell communication pathway in microorganisms, in which the expression of a number of genes, often associated with virulence factors and biofilm formation, is controlled via the production and detection of signal molecules in a population density-dependent manner [1,2]
In a search using the BLAST program, we found that aiiAQSI-1 gene has 100% similarity in nucleotide sequence with the aiiA
Our results show that the quorum quenching (QQ) enzyme AiiAQSI-1 obtained by heterologous expression in E. coli could exhibit a similar bioprotective effect as the parent Bacillus sp. strain QSI-1
Summary
Quorum sensing (QS) is a cell-to-cell communication pathway in microorganisms, in which the expression of a number of genes, often associated with virulence factors and biofilm formation, is controlled via the production and detection of signal molecules in a population density-dependent manner [1,2]. In many Gram negative bacteria, including several aquaculture pathogens, the quorum signal molecules are N-acyl homoserine lactones (AHLs), which are produced by LuxI homologs and detected by LuxR homologs [3,4,5,6]. Disruption of QS is one competition strategy used by microorganisms and higher organisms. QS disruption can occur via interference with quorum signal production or detection (LuxI and LuxR interference), or alternatively disruption of related regulatory networks [7]. Direct inactivation of quorum signal molecules by enzymatic degradation or modification is another strategy used in microbial competition [8,9]. Signal disruption referred to as quorum quenching (QQ) has been described in several biological systems and is being explored as a novel approach to
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
