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Characterisation of Heterotrophic Microorganisms Isolated form the "Grotta Azzura" of Cape Palinuro (Salerno, Italy) |
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| Authors: | Francesco Canganella Giovanna Bianconi Agata Gambacorta Chiaki Kato Katsuyuki Uematsu |
| Institution: | Department of Agrobiology &Agrochemistry –CoNISMa –University of Tusia, of Tuscia, Viterbo, Italy;Marine Microbiology Lab –CoNISMa –University of Tusia, of Tuscia, Viterbo, Italy;I.C.M.B. –C.M.I.B.–C.N.R., Arco Felice, Naples, Italy;JAMSTEC, Yokosuka, Japan |
| Abstract: | Abstract. Hydrothermal vent ecosystems have been extensively investigated during the last 20 years; shallow water hot springs (typically found below 50 m depth) have also been studied, and from these ecosystems many thermophilic and hyperthermophilic organisms were isolated and described. The submarine caves of Cape Palinuro were discovered long ago, but only during the last decades were geological and biological investigations carried out, yielding a large number of reports on this fascinating environment. During the last two years, several samples of water, mud, and/or bacterial mat were collected within the "Grotta Azzurra", and enrichment experiments were performed using peptone, starch, glucose or pullulan as main organic nutrients. Many heterotrophic strains were isolated and most of them grew optimally between 37 and 43 ° C with the addition of 0-2 % NaCl. Growth was usually observed between 10 and 50 ° C the range of growth pH was 4 to 9, and NaCl concentrations up to 10–12 % were tolerated in most cases. The analysis of 16S rDNA performed with the most representative isolates showed a close phylogenetic relationship with the genera Bacillus, Vibrio, Citrobacter and Escherichia. Moreover, an isolate showing morphological and physiological similarities with the genus Enterococcus was characterised and taxonomically described based on the 16S rDNA sequence. |
| Keywords: | Submarine caves bacteria heterotrophs marine ecosystems taxonomy |