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Sixteen trace metals were measured for the first time in cyanobacterial mats and its underlying sediment in eight lakes in the Northern Western desert, Egypt. Al, Ba, Cr, Fe, Pb, Mn, Ni, Cu and Zn concentrations in sediments were many times higher than in cyanobacterial mates. Fe, Al, Mn, Cu were the highest trace metals recorded in the lakes. Geo-...
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... The abundant artesian wells, springs, and cultivated areas drain water into the lakes in Siwa Oasis that contain mostly Na-Cl-SO 4 -type formation [121]. One of the Siwa lakes is Lake Aghormy which is located 18 m below sea level and is fed by the spring openings inside the lake which is characterized by the total dissolved solids of 220.03 g/L with a pH of 7.83 [122]. Additionally, the Lake Aghormy chemical composition is predominated by Na 1 , Ca 21 , K 1 , and Mg 21 cations with a concentration of 55, 10, 10.4, and 52 g/L, respectively, while the anions such as Cl 2 (246.8 ...
... g/L) and SO 4 22 (10.7 g/L) are being observed. The lake's sediment is significantly enriched by metals such as Cu, Cd, Se, Co, Pb, Mn, and Zn [122]. Several studies were conducted that reported the seasonal blooming of microbial mats along the Lake Aghormy margins in spring and early summer [122]. ...
... The lake's sediment is significantly enriched by metals such as Cu, Cd, Se, Co, Pb, Mn, and Zn [122]. Several studies were conducted that reported the seasonal blooming of microbial mats along the Lake Aghormy margins in spring and early summer [122]. Similarly, another lagoon named the Bardawil Lagoon is a flat low-lying plain, bordered from the north by the Sinai Mediterranean coast and covers about 600 km 2 , largely linked to the Mediterranean Sea through one natural inlet and two artificial ones, with the pH value constantly fluctuating within the alkaline side at a narrow range of 7.94À8.79 ...
... Aghormy Lake, an athalassohaline environment, is located 18 m below sea level and is fed by springs with orifices within the Lake. The Lake is characterized by total dissolved solids (TDS) of 220.03 g l À1 and a pH of 7.83 (Abd El-Karim & Goher, 2016). The chemical composition of Aghormy Lake is characterized by the dominance of Mg 2+ (52 g l À1 ), Na + (55 g l À1 ), Ca 2+ (10 g l À1 ) and K + (10.4 g l À1 ) cations, in addition to Cl À (246.8 g l À1 ) and SO 4 2À (10.7 g l À1 ) anions (El-Sayed et al., 2017). ...
... The chemical composition of Aghormy Lake is characterized by the dominance of Mg 2+ (52 g l À1 ), Na + (55 g l À1 ), Ca 2+ (10 g l À1 ) and K + (10.4 g l À1 ) cations, in addition to Cl À (246.8 g l À1 ) and SO 4 2À (10.7 g l À1 ) anions (El-Sayed et al., 2017). The lake's sediments are significantly enriched with different heavy metals, such as Cu, Cd, Se, Co, Pb, Mn, and Zn (Abd El-Karim & Goher, 2016). Several studies have documented seasonal blooming of microbial mats along the Lake margins in spring and early summer (Abd El-Karim & Goher, 2016). ...
... The lake's sediments are significantly enriched with different heavy metals, such as Cu, Cd, Se, Co, Pb, Mn, and Zn (Abd El-Karim & Goher, 2016). Several studies have documented seasonal blooming of microbial mats along the Lake margins in spring and early summer (Abd El-Karim & Goher, 2016). Bardawil Lagoon is a flat low lying plain, bordered from the north with Sinai Mediterranean coast, the south with dune belt, the west with Tineh flat, constituting part of the eastern margin of the Nile Delta plain, and from the east with the Arish-Rafah sector. ...
Culture-independent molecular study presented the first exploring and evaluation of prokaryotic communities in two desert brines; the athalassohaline Lake “Aghormy”, Siwa Oasis, Western Desert of Egypt, and the thalassohaline saltern “Sebeaka Sabkha”, Bardawil Lagoon, north coast of the Sinai. 16S rRNA gene metabarcoding generated a total of 488,828 reads from both sites, grouped into 17,741 operational taxonomic units (OTUs). 3030 OTUs were shared in both sites, while 2255 and 9426 OTUs were unique to Aghormy Lake and Sebeaka Sabkha, respectively. Both sites showed an abundance of Bacteroidetes, particularly the genera Salisaeta and Salinibacter in Aghormy and Sebeaka Sabkha, respectively. Aghormy brine was characterized by phylotypes belonging to Deinococcus-Thermus, Spirochaetes, Rhodovibrio, Piscirickettsiaceae and GMD14H09 (Deltaproteobacteria). While phylotypes assigned to AT12OctB3 (Bacteroidetes), Rhodobacteriaceae, Ectothiorhodospiraceae, and Xanthomonadaceae formed Sebeaka Sabkha bacterial community. A Cyanobacteria-like phylotype was assigned to genus Dactylococcopsis in both brines. The archaeal family, Halobacteriaceae, represented 4.8% of Sebeaka brine reads. Although some of the recorded phylotypes in both brines belonged to the same phyla, they differed in lower taxonomic ranks, implicating distant brine environments' impact on shaping halophilic communities. The metabolic prediction analyses showed a dominance of TCA cycle, branched amino acid biosynthesis and heme biosynthesis, common metabolic features for salt tolerance.
... The low raining and high evaporation rates within those lakes favored the development of hypersaline environments. The Siwa lakes have been studied from the views of physicochemical characteristics and as a source of some environmental biotechnological applications , Abd El-Karim and Goher, 2016, Mahmoud and Abd El-Karim, 2016. However, the uncultured bacterial communities within those lakes remained yet to be uncovered. ...
... The Lake Maraqi had the lowest bacterial richness, representing only two phylotypes (Figure 2 and Table 1). Maraqi showed the highest accumulation of total dissolved solid contents, 280.45 gm/L, among the studied Siwa lakes, which may shaped the bacterial richness by occurrence of only limited species that could tolerate this very extreme environment (Abd El- Karim and Goher, 2016). ...
Objective: This is the first attempt to investigate the natural dens grow of cyanobacterial mats as a source of some bioactive materials and biodiesel in some northern lakes of western desert, Egypt. Materials and Methods: The investigation included fatty acids, pigments (chlorophyll a, -carotein and phycocyanin) and biochemical contents (glycerol, total protein, carbohydrates and lipids), in addition to the % of water and ash contents from autumn- 2013 to summer-2014. Cyanobacterial mat was important source of protein, phycocyanin, -carotene and a wide range of fatty acids. Results: Protein content was 284.09 wwt% in Aghormy whereas -carotene reached to 41 times more than in carrot. The detected levels of phycocyanin (PC) in wet natural growing mats of Aghormy and Maraqi were similar to that reported in optimized dry mass production. Fatty acids spectrum found in the present study are very suitable for use as biodiesel especially in Aghormy where fatty acids characterized by high unsaturation and significant amount of palmitic and oleic fatty acids. Based on the fatty acids profile, seven biodiesel quality criteria were calculated; Cetane Number (CN), the Mass of Iodine (IV), Saponification Value (SV), the Cold Filter Plugging Point (CFPP), Long-Chain Saturated Factor (LCSF), the temperature at which the solid phase begins to form (CP) and Degree of Unsaturation (DU). Based on the biodiesel quality criteria, the best biodiesel was detected in Aghormy Lake. Conclusion: The cyanobacterial mats in Siwa oasis is considered as a natural resource of a wide range of commercially important natural products.
