Abstract

Methane represents one of the most abundant hydrocarbons on earth and a powerful greenhouse gas. Methane oxidation by microbial consortia contributes positively to the environment by decreasing methane emission to the atmosphere from different ecosystems. Aerobic methanotrophic bacteria are considered one of the main groups involved in methane oxidation. Brine pools are dynamic habitats for microbial cycling of carbon. Atlantis II Deep is the largest brine pool in the Red Sea. The pool is well known for its elevated temperature, salinity and methane concentration. Methane seeps from the deep brine to the overlying brine seawater interface layer, providing a suitable environment for aerobic methanotrophs. This study examines bacterial methane oxidation in an unexplored deep-sea environment; the Red Sea Atlantis II Deep brine pool area. Water samples were collected and subjected to serial filtration during the WHOI/KAUST/AUC OCEANUS expedition in 2008 and AEGAEO expedition in 2010 to the Red Sea. To address microbial vertical zonation in the Atlantis II Deep brine pool area, large volumes of water were sampled from 50 m, 200 m, 700 m and 1500 m below sea surface and from the brine seawater interface layer. Then 454 metagenomic libraries and pyrotags were performed for each depth to understand the diversity of aerobic methanotrophs. The data generated from the metagenomic libraries were analyzed using BLAST sequence similarity search against GenBank and the KEGG database. Additionally, we utilized the conserved functional gene particulate methane monooxygenase (pmoA) to study the diversity of aerobic methanotrophs in the interface layer. The protein based phylogeny indicated that aerobic methanotrophs reads represented between 0.2 and 0.45% of the Atlantis II Deep brine seawater interface layer and water column libraries classified reads. Few numbers of 16S rDNA methanotrophs pyrotags were detected in the interface and 1500 m sample. Based on the pmoA phylogenetic analysis, novel marine aerobic methanotrophs belonging to the Gammaproteobacteria class (type I) and potential ethane degrading methanotrophs were identified in the Atlantis II Deep brine seawater interface layer. We also identified a highly divergent pmoA that did not belong to neither type I nor type II methanotrophs.

School

School of Sciences and Engineering

Degree Name

MS in Biotechnology

First Advisor

Siam, Rania

Document Type

Thesis

Rights

The American University in Cairo grants authors of theses and dissertations a maximum embargo period of two years from the date of submission, upon request. After the embargo elapses, these documents are made available publicly. If you are the author of this thesis or dissertation, and would like to request an exceptional extension of the embargo period, please write to thesisadmin@aucegypt.edu

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