Microbial Communities in the Chemocline of a Hypersaline Deep-Sea Basin (Urania Basin, Mediterranean Sea)

Sass, Andrea, Sass, Henrik ORCID: https://orcid.org/0000-0001-8740-4224, Coolen, Marco J. L., Cypionka, Heribert and Overmann, Jörg 2001. Microbial Communities in the Chemocline of a Hypersaline Deep-Sea Basin (Urania Basin, Mediterranean Sea). Applied and Environmental Microbiology 67 (12) , pp. 5392-5402. 10.1128/AEM.67.12.5392-5402.2001

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Abstract

The Urania basin is a hypersaline sulfidic brine lake at the bottom of the eastern Mediterranean Sea. Since this basin is located at a depth of ~3,500 m below the sea surface, it receives only a small amount of phytoplankton organic carbon. In the present study, the bacterial assemblages at the interface between the hypersaline brine and the overlaying seawater were investigated. The sulfide concentration increased from 0 to 10 mM within a vertical interval of 5 m across the interface. Within this chemocline, the total bacterial cell counts and the exoenzyme activities were elevated. Employing 11 cultivation methods, we isolated a total of 70 bacterial strains. The 16S ribosomal DNA sequences of 32 of the strains were identical to environmental sequences detected in the chemocline by culture-independent molecular methods. These strains were identified as flavobacteria, Alteromonas macleodii, and Halomonas aquamarina. All 70 strains could grow chemoorganoheterotrophically under oxic conditions. Sixty-six strains grew on peptone, casein hydrolysate, and yeast extract, whereas only 15 strains did not utilize polymeric carbohydrates. Twenty-one of the isolates could grow both chemoorganotrophically and chemolithotrophically. While the most probable numbers in most cases ranged between 0.006 and 4.3% of the total cell counts, an unsually high value of 54% was determined above the chemocline with media containing amino acids as the carbon and energy source. Our results indicate that culturable bacteria thriving at the oxic-anoxic interface of the Urania basin differ considerably from the chemolithoautotrophic bacteria typical of other chemocline habitats.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences Earth and Environmental Sciences
Subjects:	Q Science > QR Microbiology
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0099-2240/ (accessed 24/02/2014)
Publisher:	American Society for Microbiology
ISSN:	0099-2240
Date of First Compliant Deposit:	30 March 2016
Last Modified:	08 May 2023 00:08
URI:	https://orca.cardiff.ac.uk/id/eprint/9316

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