Aerobic and facultative anaerobic heterotrophic bacteria associated to Mediterranean oysters and seawater

Authors

  • María Jesús Pujalte Department of Microbiology and Ecology; and Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain
  • Margarita Ortigosa Department of Microbiology and Ecology, Spain
  • María Carmen Macián Department of Microbiology and Ecology, Spain
  • Esperanza Garay Department of Microbiology and Ecology; and Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain

Keywords:

heterotrophic bacteria, phenotypic characterization, phylogenetic probes, oysters, seawater

Abstract

A comparative study on the composition and seasonal fluctuations of the main heterotrophic bacterial groups and species isolated from Mediterranean oysters and their growing-seawater was carried out. For the study we used 574 strains isolated from Marine Agar (MA) and submitted to numerical analysis of phenotypic traits in previous studies, plus 323 isolates recovered on Thiosulphate Citrate Bile Sucrose (TCBS) agar from the same samples and identified in this study. Oyster samples were dominated by halophilic fermentative bacteria during most of the year with predominance of two Vibrio species, V. splendidus (at temperatures lower than 20°C), and V. harveyi (at higher temperatures). On the contrary, Vibrio spp. was not the predominant microbiota of seawater, where most isolates had remained unidentified but corresponded to α-Proteobacteria, as shown by rDNA hybridization with phylogenetic probes in this study. Among the strict aerobes that could be identified, none of them showed a clear dominance, and many different groups were represented in very low percentages, in contrast with the major species from oyster samples. Shannon-Weaver diversity index revealed significant differences between both types of samples. No apparent seasonality was found in the distribution of seawater species, in sharp contrast with oyster-associated bacteria.

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Published

2010-03-16

Issue

Section

Research Articles