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Keywords:

  • coastal environment;
  • culturable Vibrio spp.;
  • diversity;
  • pyrH and toxR genes partial sequencing

Abstract

Aims

To describe the diversity of the culturable mesophilic and potentially pathogenic vibrios isolated at 22 and 37°C on TCBS medium, in September 2009 from seawater and surface sediments.

Methods and Results

q-PCR assays previously selected for the identification of bacterial strains isolated at 37°C were used in combination with the partial sequencing of two housekeeping genes, pyrH and toxR, to identify 315 strains isolated at 22°C. The great majority of the 37°C strains was identified by q-PCR assays, (five of the six species) with the predominance of Vibrio alginolyticus (85·9%) and V. harveyi (10·7%). The human pathogens V. parahaemolyticus and V. cholerae were rarely detected (two strains each). The 22°C strains were successfully identified by the phylogeny analysis of pyrH and toxR genes, revealing 20 Vibrio species, with the predominance of the clam pathogen V. celticus (36·8%). The Splendidus and the Harveyi groups represented the main Vibrio group at 22°C (80%) and 37°C (99·5%), respectively.

Conclusions

The combination of q-PCR assays and the sequencing of pyrH and toxR genes highlighted two different Vibrio communities at 22 and 37°C both dominated by pathogenic species for marine organisms.

Significance and Impact of the Study

The sequencing of the pyrH gene revealed to be a valuable tool to identify environmental Vibrio spp. strains isolated at 22°C, as 92·3% of them were identified in this study.