Metagenomic Analysis of Microorganisms in Hyper Saline Aquatic and Acidic Habitats of Danakil Depression of the Afar Region of Ethiopia and their Biotechnological Potential
No Thumbnail Available
Date
2021-12-04
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The Danakil Depression is one of the hottest place on Earth and is considered as an
exceptional place where different extreme environments are found. Five locations in the
Danakil Depression were studied for the presence of extremophiles and their
biotechnological potentials. The sample sites for this study are the Hyper-saline Acid
Ponds [HsAP] (Dallol [DAL], Black Water [BLA], Gaet’ale [GAL]) as well as the
Hyper-saline Aquatic Systems [HsAqS] (coastal parts of Lake Asale [LA, LADP5,
LADP6], Mud’ara pond [MUP]). All the sites were located South to Mount Dallol at less
than -100 m below sea level. In our investigation, we tested for the presence of DNAbased
life in the studied sites using Whole Metagenome Shotgun (WMS) DNA
sequencing approaches. Bioinformatic tools that adopt techniques of assembly free
(Bowtie, MetaPhlAn2) and assembly (MetaSpades, DIAMOND and MEGAN 6-CE)
were used to identify the microbial communities and predict the major nutrient metabolic
networks. Accordingly, the HsAqS were found to be mainly dominated by archaea
Operational Taxonomic Units (OTUs), while the HsAP were dominated by bacteria
OTUs. More than 95% of the total OTUs of HsAqS was grouped under phylum
Euryarchaea, while more than 90% of the OTUs of HsAP was classified in the phyla
Proteobacteria, Actinobacteria and Firmicutus. Halonotius sp J07HN6 and unclassified
Salinibacter ruber were the two abundant archaeal and bacterial OTUs in the HsAqS,
respectively. On the other hand, unclassified strain of Paraburkholderia fungorum was
profiled as the most abundant OTU for DAL and BLA, while unclassified Escherichia
and unclassified Burkholderia were top two abundant OTUs for GAL. Insilico prediction
of gene functions and metabolic pathways using SEED and KEGG indicated presence of
carbon fixation, sulfate oxidation, assimilative nitrogen and sulfate reduction reactions in
DAL and BLA samples. Carbon fixation was also predicted in the HsAqS while
methanogenesis was exclusively predicted in GAL. Based on the investigation of the
sources of the genes of interest, it is clear that syntrophic metabolism is the main strategy
adapted to utilize the nutrients in the studied sampling sites. Moreover, the predicted
genes from DAL’s and BLA’s nitrogen metabolism helped to discover new protein
sequences of cysteine desulfurase and [4Fe-4S] ferredoxin with less than 80% similarity
to the homologous reference protein sequence. Images of DAL extremophiles obtained
from Transmission Electron Microscopy (TEM) showed high production of nano sized
Extracellular Membrane Vesicles (EMV). Further investigation on resistance of DAL’s
extremophiles to phenolic compounds under lysing conditions indirectly signified their
bio-remediation capability. In general, this preliminary investigation indicates great
biotechnological and bioremediation potentials of extremophiles of Danakil Depression.
Description
Keywords
Danakil Depression, Extremophiles, Metagenomis, Insilico, Extreme Environment