The motility behaviour of PUGSK8 was evaluated using twitching, swimming and swarming plate assays

The motility behaviour of PUGSK8 was evaluated using twitching, swimming and swarming plate assays. there is very limited information on the potential anti-infective and anti-virulence mechanisms involving PHB. In this LTBP1 study, we aim to examine the effect of PHB on inhibition of the virulence cascade of such as biofilm formation, luminescence, motility behaviour, haemolysin and quorum sensing. A luminescent PUGSK8, tentatively identified as PUGSK8 was tested for production of extracellular virulence factors and then established as a potential shrimp pathogen based on challenge experiments. The ability of PUGSK8 to form biofilms and the effect of PHB on biofilm formation was tested in a 96-well microtitre-plate assay system. The motility behaviour of PUGSK8 was evaluated using twitching, swimming and swarming plate assays. Reporter strains such as CV026 and were used to detect quorum-sensing molecules. Gas chromatographyCmass spectrometry spectral analysis was performed to elucidate the fragmentation pattern and structure of PUGSK8 was quantified as the amount of the enzyme solution to hydrolyse 1?g of PHB per min. An challenge experiment was performed using a gnotobiotic Artemia assay. Of the 27 isolates tested, the PUGSK8 strain was selected for target-specific assays based on SU10944 the high intensity of luminescence and production of virulence factors. The virulence cascade detected in PUGSK8 include luminescence, motility behaviour, biofilm formation, quorum sensing and haemolysin production. Thus inhibition/degradation of the virulence cascade would be an effective approach to contain infections in aquatic animals. In this report, we demonstrate that the degradation intermediate of PHB effectively inhibits biofilm formation, luminescence, motility behaviour, haemolysin production and the PUGSK8 remains unaffected in the presence of PHB, with PHB degradation being detected in the media. PHB depolymerase activity in PUGSK8 results in the release of degradation intermediates include a short-chain -hydroxy butyric acid, which inhibits the virulence cascade in PUGSK8. Thus, a molecule that targets quorum sensing and the virulence cascade and which is species/strain-specific could prove to be an effective alternative to antimicrobial agents to control the pathogenesis of outbreaks in aquatic systems. Introduction Member of the genus are common inhabitants of various aquatic environments. They typically exist either as free-living organisms or associated with hosts such as zooplankton, which are known to protect the from a variety of different environmental stresses. have also been reported to be associated with many higher organisms in marine environments including corals, crabs, molluscs and fish among others. Although the majority of these SU10944 associations are not harmful to the host, there are examples where spp. are pathogenic with and being the causative agents of disease in commercially important organisms such as oysters and corals, respectively. Others include the luminescent strain and which are the most common pathogens of giant black tiger shrimp in Asia and pose the principal threat faced by shrimp hatcheries all over the world. is believed to be the primary causative agent of the recent mass mortality in shrimp due to early-mortality syndrome.2 The biofilm-forming capacity of is well documented, both in natural habitats and under laboratory conditions.3C5 Among the SU10944 shrimp pathogens, the biofilm-forming capacity of has been established on cement slab, plastic and steel coupon surfaces. 6 Adhesion and proliferation within the biofilm is an established mechanism of pathogenesis and infection of in spp.,4,8C12 with biofilm formation being commonly associated with colonisation and subsequent pathogenesis in hosts by vibrios in marine environments.13 To date, only a few studies have been carried out on biofilm inhibition in spp.14C16 Bacteria in biofilms are surrounded by an extracellular matrix that can restrict diffusion of antimicrobial agents.17 In addition changes in the membrane sterol composition in bacteria during biofilm development can also increase the microbial cells resistant to antibiotics.18,19 Quorum sensing is a cell-to-cell communication process in bacteria that involves the production, release, detection and collective response to extracellular signal molecules called autoinducers, which control the phenotypic expression of bioluminescence, biomass development, ecological succession, competence, biofilm formation, motility and the production of virulence factors.20,21 Gram-negative quorum-sensing circuits rely on dependent acyl homoserine lactones.