Diversity of Bacteria and Archaea associated with a carbonate-rich metalliferous sediment sample from the Rainbow vent field on the Mid-Atlantic Ridge

• Published in: Environmental microbiology Vol. 7; no. 5; pp. 698 - 714
• Main Authors: Nercessian, Olivier, Fouquet, Yves, Pierre, Catherine, Prieur, Daniel, Jeanthon, Christian
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.05.2005; Society for Applied Microbiology and Wiley-Blackwell
• Subjects: Actinobacteria; Archaea; Archaea - genetics; Archaea - isolation & purification; Atlantic Ocean; Bacteria - genetics; Bacteria - isolation & purification; Base Sequence; Carbon Isotopes - analysis; Carbonates - analysis; Cloning, Molecular; DNA, Archaeal - chemistry; DNA, Archaeal - genetics; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Earth Sciences; Genetic Variation; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Geophysics; Hot Temperature; Minerals - analysis; Molecular Sequence Data; Oxygen Isotopes - analysis; Phylogeny; Physics; Planctomycetes; Polymerase Chain Reaction; RNA, Ribosomal, 16S - chemistry; RNA, Ribosomal, 16S - genetics; Sciences of the Universe; Sequence Alignment; Atlantic Ocean
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/j.1462-2920.2005.00744.x

Summary Two sediment cores were collected in an inactive area of the deep‐sea hydrothermal vent field Rainbow (36°N on the Mid‐Atlantic Ridge). Metals and carbonates were abundant throughout the cores; calcite (CaCO3) was found throughout the cores while dolomite [CaMg(CO3)2] and siderite (FeCO3) were only found in deeper layers. Using polymerase chain reaction (PCR)‐amplified 16S rRNA gene sequence analysis, we examined the bacterial and archaeal diversity in a sediment layer that contained the three carbonates. The retrieved bacterial and archaeal sequences were new and less than 4% of the sequences exhibited 94% or more identity with that of cultured organisms. The analysis of the composition of the bacterial library  revealed  a  high  diversity  of  sequences.  Half of the bacterial clones was affiliated to the γ‐Proteobacteria. Most of them had environmental sequences retrieved from deep‐sea sediments as closest relatives, some of which being distantly related to free‐living and symbiotic sulfur‐oxidizers. Other sequences clustered in the α‐, δ‐ and ɛ‐Proteobacteria, the ‘Bacteroidetes’, the ‘Planctomycetes’, the ‘Nitrospirae’, the ‘Actinobacteria’, the ‘Chlorobi ’ and the ‘Verrumicrobia’. Based on clonal abundance and sequence comparisons, phylotype groups putatively involved in the oxydation of sulfur compounds appeared to dominate in the studied sample. The majority of the archaeal sequences clustered in an euryarchaeotic lineage recently identified in the walls of black smokers suggesting a possible thermophilic way of life of these uncultured microorganisms. Oxygen isotopic composition of siderite and dolomite indicated that they were formed at 67°C and 94°C respectively. Together with chemical and microbiological data, this suggested that hydrothermal fluids may have circulated through this sediment.