Vibrio anguillarum colonization of rainbow trout integument requires a DNA locus involved in exopolysaccharide transport and biosynthesis

Abstract

Vibrio anguillarum, part of the normal flora of the aquatic milieu, causes a fatal haemorrhagic septicaemia in marine fish. In this study, a rainbow trout model was used to characterize the colonization of fish skin by V. anguillarum. Within 5 h after infection, the bacterium penetrated the skin mucosal layer, attached to the scales within 12 h, and formed a biofilm by 24-48 h. Two divergently transcribed putative operons, orf1-wbfD-wbfC-wbfB and wza-wzb-wzc, were shown to play a role in skin colonization and virulence. The first operon encodes proteins of unknown function. The wza-wzb-wzc genes encode a secretin, tyrosine kinase and tyrosine phosphatase, respectively, which are similar to proteins in polysaccharide transport complexes. Compared with the wild type, polar mutations in wza, orf1 and wbfD caused a decrease in exopolysaccharide biosynthesis but not lipopolysaccharide biosynthesis. The wza and orf1 mutants did not attach to fish scales; whereas, the wbfD mutant had a wild-type phenotype. Moreover, the wza and orf1 mutants had decreased exoprotease activity, in particular the extracellular metalloprotease EmpA, as well as mucinase activity suggesting that these mutations also affect exoenzyme secretion. Thus, the exopolysaccharide transport system in V. anguillarum is required for attachment to fish skin, possibly preventing mechanical removal of bacteria via natural sloughing of mucus.

Effect of TDA‐producing Phaeobacter inhibens on the fish pathogen Vibrio anguillarum in non‐axenic algae and copepod systems

“…Strain NB10, used for the adhesion/invasion experiment, was isolated from the Gulf of Bothnia and is pathogenic towards turbot and halibut larvae (Rønneseth et al ., 2017). The strain has been tagged by insertion of plasmid pNQFlaC4‐gfp27 ( cat , gfp ) into the chromosome (Croxatto et al ., 2007) and was provided by Prof. Debra L. Milton (Department of Molecular Biology, Umeå University). The highly virulent V. anguillarum strain 90‐11‐286 (Rønneseth et al ., 2017) was used in the co‐culture experiments and was isolated from diseased rainbow trout ( Oncorhynchus mykiss ) from a Danish aquaculture (Pedersen and Larsen, 1993; Skov et al ., 1995).…”

Complete Genome Sequence of the Marine Fish Pathogen Vibrio anguillarum Harboring the pJM1 Virulence Plasmid and Genomic Comparison with Other Virulent Strains of V. anguillarum and V. ordalii

“…on May 11, 2018 by guest http://iai.asm.org/ wbfB-wbfD, and orf1, shown to be important in exopolysaccharide biosynthesis (15). These genes are also located within this cluster.…”

Regulation of type III secretion system 1 gene expression inVibrio parahaemolyticusis dependent on interactions between ExsA, ExsC, and ExsD

“…The DNA fragment of exsC gene was digested with SmaI and SpeI. Digested fragments of exsC and Ptac were ligated into pDM31, 54 that was pre-digested with SacI and SpeI, resulting in the plasmid pDM31_Ptac_exsC_ His. This plasmid was electroporated into E. coli S17 resulting Figure 11.…”