The Atlantis II Deep is the most studied and largest brine pool in the Red Sea. It is an active hydrothermal habitat with unique physical conditions. Its unique characteristics (70°C temperature, 26% salinity, pH 5.2) caused it to be a very attractive marine ecosystem for microbiological and metagenomics studies. Sediments of the Atlantis II Deep brine were investigated for the presence of extremophilic bacteria using a cultivation approach combined with phylogenetic analysis. Two different cultivation methods were utilized: substrate gradient cultures and minimal salts medium supplemented with various combinations of electron donors and acceptors. A bacterial culture enriched from the deepest layer of the sediment core was able to anaerobically reduce arsenate to arsenite. The most abundant member in this culture was identified and found to belong to the genus Pseudomonas. The 16S rDNA sequences obtained from this culture were phylogenetically clustered with sequences belonging to Pseudomonas fluorescens, which plays an important role in arsenate accumalation and detoxification in soils. One heterotrophic bacterium predominated the microbial community in two anoxic enrichment cultures amended with sulfide and sulfate independently. This bacterium was phylogenetically assigned to uncultured Cytophaga-Flavobacterium group, whose members are well-known for their sulfur-oxidation capability. The most abundant bacterium in an aerobic enrichment culture was identified and assigned to the genus Brevibacillus. Several members of Brevibacillus have been reported to produce cellulase. In conclusion, our preliminary cultivation-based analysis presents potential thermophilic, halophilic bacteria that are able to thrive under several abiotic stresses. These bacteria might contribute to the anaerobic degradation of organic substrates, in addition to reducing the arsenate enriched at the seafloor sediments.


School of Sciences and Engineering

Degree Name

MS in Biotechnology

First Advisor

Siam, Rania

Committee Member 1

Mostafa, Ahmed

Committee Member 2

Elkheshin, Dina

Committee Member 3

Abdel Latif, Ahmed

Document Type



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