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Diversity of Bacillus-like organisms isolated from deep-sea hypersaline anoxic sediments.

Sass AM, McKew BA, Sass H, Fichtel J, Timmis KN, McGenity TJ - Saline Syst. (2008)

Bottom Line: Two third of the isolates did not grow at in-situ salinities and were presumably present as endospores.Some of the novel isolates affiliating with the genus Pontibacillus grew well under anoxic conditions in sulfidic medium by fermentation or anaerobic respiration using dimethylsulfoxide or trimethylamine N-oxide as electron acceptor.Some of the halophilic, facultatively anaerobic relatives of Bacillus appear well adapted to life in this hostile environment and suggest the presence of actively growing microbial communities in the NaCl-rich, deep-sea brine-lake sediments.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK. sassam@Cardiff.ac.uk

ABSTRACT

Background: The deep-sea, hypersaline anoxic brine lakes in the Mediterranean are among the most extreme environments on earth, and in one of them, the MgCl2-rich Discovery basin, the presence of active microbes is equivocal. However, thriving microbial communities have been detected especially in the chemocline between deep seawater and three NaCl-rich brine lakes, l'Atalante, Bannock and Urania. By contrast, the microbiota of these brine-lake sediments remains largely unexplored.

Results: Eighty nine isolates were obtained from the sediments of four deep-sea, hypersaline anoxic brine lakes in the Eastern Mediterranean Sea: l'Atalante, Bannock, Discovery and Urania basins. This culture collection was dominated by representatives of the genus Bacillus and close relatives (90% of all isolates) that were investigated further. Physiological characterization of representative strains revealed large versatility with respect to enzyme activities or substrate utilization. Two third of the isolates did not grow at in-situ salinities and were presumably present as endospores. This is supported by high numbers of endospores in Bannock, Discovery and Urania basins ranging from 3.8 x 10(5) to 1.2 x 10(6) g(-1) dw sediment. However, the remaining isolates were highly halotolerant growing at salinities of up to 30% NaCl. Some of the novel isolates affiliating with the genus Pontibacillus grew well under anoxic conditions in sulfidic medium by fermentation or anaerobic respiration using dimethylsulfoxide or trimethylamine N-oxide as electron acceptor.

Conclusion: Some of the halophilic, facultatively anaerobic relatives of Bacillus appear well adapted to life in this hostile environment and suggest the presence of actively growing microbial communities in the NaCl-rich, deep-sea brine-lake sediments.

No MeSH data available.


Location of the four deep-sea hypersaline anoxic basins within the Eastern Mediterranean Sea (coordinates for the basins: L'Atalante 35.18 N 21.41 E, Discovery 35.17 N 21.41 E, Urania 35.14 N 21.31 E, Bannock 34.17 N 20.00 E).
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Figure 1: Location of the four deep-sea hypersaline anoxic basins within the Eastern Mediterranean Sea (coordinates for the basins: L'Atalante 35.18 N 21.41 E, Discovery 35.17 N 21.41 E, Urania 35.14 N 21.31 E, Bannock 34.17 N 20.00 E).

Mentions: Four of the basins in the Eastern Mediterranean Sea, l'Atalante, Bannock, Discovery and Urania basins (Fig. 1) have been sampled and studied to better understand their biogeochemistry, ecology and biotechnological potential. The physico-chemical properties of the hypersaline brine lakes have been described by van der Wielen et al. [5], but in brief l'Atalante and Bannock brines contain ions roughly in proportion to those found in seawater but almost at the point of sodium chloride saturation (~8 times seawater concentration). The Urania brine has a slightly lower salinity, but exhibits one of the highest sulfide concentrations measured in marine environments [5,6]; it also has a very high methane concentration and in parts an elevated temperature, possibly caused by a deep source of the brine [7]. The Discovery basin is unique in that it derives from bischofite (MgCl2·6H2O), resulting in a ~5 Molar magnesium chloride brine [8], representing the marine environment with the lowest reported water activity [9].


Diversity of Bacillus-like organisms isolated from deep-sea hypersaline anoxic sediments.

Sass AM, McKew BA, Sass H, Fichtel J, Timmis KN, McGenity TJ - Saline Syst. (2008)

Location of the four deep-sea hypersaline anoxic basins within the Eastern Mediterranean Sea (coordinates for the basins: L'Atalante 35.18 N 21.41 E, Discovery 35.17 N 21.41 E, Urania 35.14 N 21.31 E, Bannock 34.17 N 20.00 E).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2464584&req=5

Figure 1: Location of the four deep-sea hypersaline anoxic basins within the Eastern Mediterranean Sea (coordinates for the basins: L'Atalante 35.18 N 21.41 E, Discovery 35.17 N 21.41 E, Urania 35.14 N 21.31 E, Bannock 34.17 N 20.00 E).
Mentions: Four of the basins in the Eastern Mediterranean Sea, l'Atalante, Bannock, Discovery and Urania basins (Fig. 1) have been sampled and studied to better understand their biogeochemistry, ecology and biotechnological potential. The physico-chemical properties of the hypersaline brine lakes have been described by van der Wielen et al. [5], but in brief l'Atalante and Bannock brines contain ions roughly in proportion to those found in seawater but almost at the point of sodium chloride saturation (~8 times seawater concentration). The Urania brine has a slightly lower salinity, but exhibits one of the highest sulfide concentrations measured in marine environments [5,6]; it also has a very high methane concentration and in parts an elevated temperature, possibly caused by a deep source of the brine [7]. The Discovery basin is unique in that it derives from bischofite (MgCl2·6H2O), resulting in a ~5 Molar magnesium chloride brine [8], representing the marine environment with the lowest reported water activity [9].

Bottom Line: Two third of the isolates did not grow at in-situ salinities and were presumably present as endospores.Some of the novel isolates affiliating with the genus Pontibacillus grew well under anoxic conditions in sulfidic medium by fermentation or anaerobic respiration using dimethylsulfoxide or trimethylamine N-oxide as electron acceptor.Some of the halophilic, facultatively anaerobic relatives of Bacillus appear well adapted to life in this hostile environment and suggest the presence of actively growing microbial communities in the NaCl-rich, deep-sea brine-lake sediments.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK. sassam@Cardiff.ac.uk

ABSTRACT

Background: The deep-sea, hypersaline anoxic brine lakes in the Mediterranean are among the most extreme environments on earth, and in one of them, the MgCl2-rich Discovery basin, the presence of active microbes is equivocal. However, thriving microbial communities have been detected especially in the chemocline between deep seawater and three NaCl-rich brine lakes, l'Atalante, Bannock and Urania. By contrast, the microbiota of these brine-lake sediments remains largely unexplored.

Results: Eighty nine isolates were obtained from the sediments of four deep-sea, hypersaline anoxic brine lakes in the Eastern Mediterranean Sea: l'Atalante, Bannock, Discovery and Urania basins. This culture collection was dominated by representatives of the genus Bacillus and close relatives (90% of all isolates) that were investigated further. Physiological characterization of representative strains revealed large versatility with respect to enzyme activities or substrate utilization. Two third of the isolates did not grow at in-situ salinities and were presumably present as endospores. This is supported by high numbers of endospores in Bannock, Discovery and Urania basins ranging from 3.8 x 10(5) to 1.2 x 10(6) g(-1) dw sediment. However, the remaining isolates were highly halotolerant growing at salinities of up to 30% NaCl. Some of the novel isolates affiliating with the genus Pontibacillus grew well under anoxic conditions in sulfidic medium by fermentation or anaerobic respiration using dimethylsulfoxide or trimethylamine N-oxide as electron acceptor.

Conclusion: Some of the halophilic, facultatively anaerobic relatives of Bacillus appear well adapted to life in this hostile environment and suggest the presence of actively growing microbial communities in the NaCl-rich, deep-sea brine-lake sediments.

No MeSH data available.