Deep-sea anoxic brine pools are one of the most extreme ecosystems on Earth, which are
characterized by drastic changes in salinity, temperature, and oxygen concentration. The
interface between the brine and overlaying seawater represents a boundary of oxic-anoxic
layer and a steep gradient of redox potential that would initiate favorable conditions for
divergent metabolic activities, mainly methanogenesis and sulfate reduction. This study
aimed to investigate the diversity of Bacteria, particularly sulfate-reducing communities,
and their ecological roles in the interfaces of five geochemically distinct brine pools in
the Red Sea. Performing a comprehensive study would enable us to understand the
significant role of the microbial groups in local geochemical cycles. Therefore, we
combined culture-dependent approach and molecular methods, such as 454
pyrosequencing of 16S rRNA gene, phylogenetic analysis of functional marker gene
encoding for the alpha subunits of dissimilatory sulfite reductase (dsrA), and single-cell
genomic analysis to address these issues. Community analysis based on 16S rRNA gene
sequences demonstrated high bacterial diversity and domination of Bacteria over Archaea
in most locations. In the hot and multilayered Atlantis II Deep, the bacterial communities
were stratified and hardly overlapped. Meanwhile in the colder brine pools, sulfatereducing
Deltaproteobacteria were the most prominent bacterial groups inhabiting the interfaces. Corresponding to the bacterial community profile, the analysis of dsrA gene
sequences revealed collectively high diversity of sulfate-reducing communities.
Desulfatiglans-like dsrA was the prevalent group and conserved across the Red Sea brine
pools. In addition to the molecular studies, more than thirty bacterial strains were
successfully isolated and remarkably were found to be cytotoxic against the cancer cell
lines. However, none of them were sulfate reducers. Thus, a single-cell genomic analysis
was used to study the metabolism of uncultured phyla without having them in culture.
We analysed ten single-cell amplified genomes (SAGs) of the uncultivated euryarchaeal
Marine Benthic Group E (MBGE), which contain a key enzyme for sulfate reduction.
The results showed the possibility of MBGE to grow autotrophically only with carbon
dioxide and hydrogen. In the absence of adenosine 5’-phosphosulfate reductase, we
hypothesized that MBGE perform sulfite reduction rather than sulfate reduction to
conserve energy.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/552806 |
| Date | 05 1900 |
| Creators | Hikmawan, Tyas I. |
| Contributors | Stingl, Ulrich, Biological and Environmental Sciences and Engineering (BESE) Division, Moran, Xose Anxelu G., Pain, Arnab, Jebbar, Mohamed |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2016-05-21, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2016-05-21. |
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