Project description:It was found that Vibrio splendidus could survive under high concentration of tetracycline, and the coelomic fluid of sea cucumber increased the tolerance of Vibrio splendidus to tetracycline. Therefore, the transcriptome was determined to find the cause of drug resistance in Vibrio splendidus.
Project description:Mussels (Mytilus galloprovincialis) were exposed during 24 hours to a waterborne infection with 10E8 CFU/ml Vibrio splendidus (reference strain LGP32) in the tank water. Five biological replicates were used for each infected and control conditions.
Project description:In marine Vibrio species, chitin-induced natural transformation enables bacteria to take up DNA from the external environment and integrate it into their genome via homologous recombination. Expression of the master competence regulator TfoX bypasses the need for chitin induction and drives expression of the genes required for competence in several Vibrio species. Here, we show that TfoX expression in two Vibrio campbellii strains, DS40M4 and NBRC 15631, enables high frequencies of natural transformation. Conversely, transformation was not achieved in the model quorum-sensing strain V. campbellii BB120 (previously classified as Vibrio harveyi). Surprisingly, we find that quorum sensing is not required for transformation in V. campbellii DS40M4. This result is in contrast to Vibrio cholerae that requires the quorum-sensing regulator HapR to activate the competence regulator QstR. However, similar to V. cholerae, QstR is necessary for transformation in DS40M4. To investigate the difference in transformation frequencies between BB120 and DS40M4, we used previously studied V. cholerae competence genes to inform a comparative genomics analysis coupled with transcriptomics. BB120 encodes homologs of all known competence genes, but most of these genes were not induced by ectopic expression of TfoX, which likely accounts for the non-functional natural transformation in this strain. Comparison of transformation frequencies among Vibrio species indicates a wide disparity among even closely related strains, with Vibrio vulnificus having the lowest functional transformation frequency. We show that ectopic expression of both TfoX and QstR is sufficient to produce a significant increase in transformation frequency in Vibrio vulnificus.
Project description:The quorum regulatory cascade is poorly characterized in Vibrio parahaemolyticus, in part because swarming and pathogenicity - the hallmark traits of the organism - are repressed by this scheme of gene control. As a consequence, many isolates appear silenced for quorum sensing via phase variation. In these studies, we examine a swarm proficient, virulent strain and find an altered function allele of the central quorum regulator luxO. We use this allele, which produces a constitutively active LuxO, to probe the upstream elements of the pathway and demonstrate their functionality for the first time. We find that the state of luxO affects expression of three small regulatory RNAS (Qrrs) and the activity of a translational fusion in opaR, the central output regulator. We use microarray profiling to determine the OpaR regulon, which was found to encompass ~5.2% of the genome. The quorum sensing proficient strain seems adapted for a sessile, community lifestyle; it is competent to uptake DNA, produces much capsular polysaccharide, has a high level of c-di-GMP, and strongly expresses one type six secretion system. Expressing the entire surface sensing regulon and numerous methyl accepting chemotaxis proteins, the quorum-disrupted cell type seems prepared for a mobile lifestyle. It is also cytotoxic to host cells in co-culture and expresses distinct type six as well as type three secretion systems. Thus, the scope and nature of the genes in the OpaR regulon provide many clues to the distinguishing traits of this Vibrio species as well as to the quite divergent survival strategies of the quorum ON/OFF phase variants The gene expression profiles of different strains of Vibrio parahaemolyticus cells grown on rich medium and compared using Affymetrix custom microarrays.