Serotyping & molecular characterization for study of genetic diversity among seafood associated nontyphoidal Salmonella serovars.

Background & Objectives: Infections due to seafood associated Salmonella serovars are great risk to public health. Different phenotypic characteristics have been used previously for epidemiological investigation of Salmonella. Beyond the phenotypic characterization, a reliable genetic level discriminatory method is required.

Quorum sensing regulation of virulence gene expression in Vibrio harveyi in vitro and in vivo during infection of gnotobiotic brine shrimp larvae.

In this study, we investigated quorum sensing regulation of virulence genes in Vibrio harveyi by determining their expression levels, both in vitro and in vivo during infection of gnotobiotic brine shrimp. The quorum sensing master regulator luxR and the vhp metalloprotease showed around threefold and fivefold higher expression levels in a luxO mutant with maximum quorum sensing activity than in a luxO mutant with minimum quorum sensing activity. There was no difference in expression of the vhh haemolysin gene between the two mutants.

gcpA (stm1987) is critical for cellulose production and biofilm formation on polystyrene surface by Salmonella enterica serovar Weltevreden in both high and low nutrient medium.

Biofilm formation by Salmonella is a serious concern in the food-processing industry and the persistence of the organism in biofilms becomes a constant source of contamination. Since there is zero tolerance for Salmonella in foods, it is important to understand the mechanism of biofilm formation and to prevent the formation. Therefore, this study aimed at investigating the biofilm-forming ability of seafood isolates of Salmonella enterica serovar Weltevreden (S.

In vitro and in vivo expression of virulence genes in Vibrio isolates belonging to the Harveyi clade in relation to their virulence towards gnotobiotic brine shrimp (Artemia franciscana).

Vibrios belonging to the Harveyi clade are pathogenic marine bacteria affecting both vertebrates and invertebrates, thereby causing a severe threat to the aquaculture industry. In this study, the expression of haemolysin, metalloprotease, serine protease, the quorum sensing master regulator LuxR and the virulence regulator ToxR in different Harveyi clade isolates was measured with reverse transcriptase real-time PCR with specific primers. There was relatively low variation in the in vitro expression levels of the quorum sensing master regulator luxR (sevenfold), whereas for the other genes, the difference in expression between the isolates showing lowest and highest expression levels was over 25-fold.