Microbial Diversity at a Hot, Shallow-Sea Hydrothermal Vent in the Southern Tyrrhenian Sea (Italy)

Abstract

Microbial community thriving at shallow hydrothermal vent named Black Point, close to the Island of Panarea in the Southern Tyrrhenian Sea (Italy), was studied by microscopic, cultural and molecular methods. New strains of Bacillus and Geobacillus were isolated. Members of sulphur-oxidizing bacteria, belonging to the genera Halothiobacillus and Thiomicrospira were demonstrated by both culture-dependent and -independent methods. Genetic diversity of Bacteria was higher than that of Archaea. Bacterial 16S rRNA gene sequences from Black Point showed low levels of similarity with other yet deposited sequences, suggesting that new bacterial phylotypes are present in this site. Dominant populations of Bacteria belonged to uncultured members of Proteobacteria (mainly of the class Gammaproteobacteria), Firmicutes and Acidobacteriaceae. Primary production appeared to be supported by chemosynthetic and photosynthetic bacteria affiliated with members of Gammaproteobacteria. Most of the archaeal sequences matched those of yet-uncultivated Archaea, thus their role at this vent is not well understood.

Keywords:

• archaea
• bacteria
• prokaryotic community
• PCR-DGGE
• shallow hydrothermal vents

We wish thank Dr. Franco Italiano from Istituto Nazionale di Geofisica e Vulcanologia (CNR), Palermo (Italy) for the field technical support in sampling operations and for providing us the geochemical data.