Genetic Diversity and Evolution of Marine Animals Isolated in Marine Lakes

ABSTRACTPhotobacterium damselaesubsp.damselaecauses vibriosis in a variety of marine animals, including fish species of importance in aquaculture. It also may cause wound infections in humans that can progress to a fatal outcome. Two major virulence factors are encoded within the large conjugative plasmid pPHDD1, the phospholipase D damselysin (Dly) and the pore-forming toxin phobalysin P (PhlyP). The two toxins exert hemolytic and cytolytic activities in a synergistic manner. Even though PhlyP has close homologues in manyVibriospecies, it has unique features that differentiate it from related toxins. Dly phospholipase constitutes a singular trait ofP. damselaesubsp.damselaeamong theVibrionaceae, although related toxins are found in members of theAeromonadaceae. Fish farm outbreaks can also be caused by plasmidless strains. Such observations led to the characterization of two ubiquitous chromosome-encoded toxins with lesser cytolytic activity, the pore forming-toxin phobalysin C (PhlyC) and the phospholipase-hemolysin PlpV. The high genetic diversity of this pathogen deserves special attention, as it has a number of strain-specific features, including the cell envelope polysaccharide synthesis clusters. Fish outbreaks are likely caused by multiclonal populations which contain both plasmidless and pPHDD1-harboring isolates and not by well-adapted clonal complexes. Still, among such genetic heterogeneity, it is feasible to identify conserved weak points in the biology of this bacterium: the two-component regulatory system RstAB (CarSR) was found to be necessary for the maximal production of virulence factors, and its inactivation severely impaired virulence.

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Genetic heterogeneity amongVibrio alginolyticusstrains, and design of a PCR-based identification method usinggyrBgene sequence

Canadian Journal of Microbiology ◽

10.1139/cjm-2017-0269 ◽

2018 ◽

Vol 64 (1) ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Supansa Bunpa ◽

Mitsuaki Nishibuchi ◽

Jumroensri Thawonsuwan ◽

Natthawan Sermwittayawong

Keyword(s):

Genetic Diversity ◽

Chain Reaction ◽

Marine Animals ◽

Gyrb Sequence ◽

Highly Sensitive ◽

Southern Thailand ◽

Polymerase Chain ◽

Species Specific ◽

Dna Template ◽

Vibrio Spp

Vibrio alginolyticus, a pathogen among humans and marine animals, is ubiquitous in marine environments. The aims of this study were to analyze the relationships between genetic diversity and origins, and to develop new primers based on the gyrB sequence to identify V. alginolyticus isolated from various sources. To determine the genetic diversity of this bacterium, an arbitrarily primed polymerase chain reaction (AP-PCR) technique was performed on 36 strains of V. alginolyticus isolated from diarrhea patients and from diseased marine animals and environments in southern Thailand. The results showed distinct DNA fingerprints of all strains, indicating that they are genetically heterogeneous. For species-specific identification of V. alginolyticus, primers targeting the gyrB gene of V. alginolyticus were developed. Thirty reference Vibrio spp., 13 non-Vibrio spp., and 160 strains of V. alginolyticus isolated from various sources in southern Thailand were used to evaluate the specificity of these primers. Our results showed that the gyrB primers could specifically identify V. alginolyticus from all sample types. In addition, the detection limit of the PCR was at least 95 pg of DNA template. Therefore, we concluded that the newly designed gyrB primers are rapid, highly sensitive, and specific to identify V. alginolyticus isolated from various sources.

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