Egypt's Red Sea coast: phylogenetic analysis of cultured microbial consortia in industrialized sites

Deciphering the functional and structural complexity of the Solar Lake flat mat microbial benthic communities

The Solar Lake in Taba, Egypt, encompasses one of the few modern-day microbial mats' systems metabolically analogous to Precambrian stromatolites. Solar Lake benthic communities and their adaptation to the Lake's unique limnological cycle have not been described for over two decades. In this study, we revisit the flat mat and describe the summer's shallow water versus exposed microbial community; the latter occurs in response to the seasonal partial receding of water. We employed metagenomic NovaSeq-6000 shotgun sequencing and 16S rRNA, mcrA, and dsrB quantitative PCR. A total of 292 medium-to-high-quality metagenome-assembled genomes (MAGs) were reconstructed. At the structural level, Candidatus Aenigmatarchaeota, Micrarchaeota, and Omnitrophota MAGs were exclusively detected in the shallow-water mats, whereas Halobacteria and Myxococcota MAGs were specific to the exposed microbial mat. Functionally, genes involved in reactive oxygen species (ROS) detoxification and osmotic pressure were more abundant in the exposed than in the shallow-water microbial mats, whereas genes involved in sulfate reduction/oxidation and nitrogen fixation were ubiquitously detected. Genes involved in the utilization of methylated amines for methane production were predominant when compared with genes associated with alternative methanogenesis pathways. Solar Lake methanogen MAGs belonged to Methanosarcinia, Bathyarchaeia, Candidatus Methanofastidiosales, and Archaeoglobales. The latter had the genetic capacity for anaerobic methane oxidation. Moreover, Coleofasciculus chthonoplastes, previously reported to dominate the winter shallow-water flat mat, had a substantial presence in the summer. These findings reveal the taxonomic and biochemical microbial zonation of the exposed and shallow-water Solar Lake flat mat benthic community and their capacity to ecologically adapt to the summer water recession.

IMPORTANCE

Fifty-five years ago, the extremophilic "Solar Lake" was discovered on the Red Sea shores, garnering microbiologists' interest worldwide from the 1970s to 1990s. Nevertheless, research on the lake paused at the turn of the millennium. In our study, we revisited the Solar Lake benthic community using a genome-centric approach and described the distinct microbial communities in the exposed versus shallow-water mat unveiling microbial zonation in the benthic communities surrounding the Solar Lake. Our findings highlighted the unique structural and functional adaptations employed by these microbial mat communities. Moreover, we report new methanogens and phototrophs, including an intriguing methanogen from the Archaeoglobales family. We describe how the Solar Lake's flat mat microbial community adapts to stressors like oxygen intrusion and drought due to summer water level changes, which provides insights into the genomic strategies of microbial communities to cope with altered and extreme environmental conditions.

Seasonal Changes in the Biochemical Composition of Dominant Macroalgal Species along the Egyptian Red Sea Shore

Macroalgae are significant biological resources in coastal marine ecosystems. Seasonality influences macroalgae biochemical characteristics, which consequentially affect their ecological and economic values. Here, macroalgae were surveyed from summer 2017 to spring 2018 at three sites at 7 km (south) from El Qusier, 52 km (north) from Marsa Alam and 70 km (south) from Safaga along the Red Sea coast, Egypt. Across all the macroalgae collected, Caulerpa prolifera (green macroalgae), Acanthophora spicifera (red macroalgae) and Cystoseira myrica, Cystoseira trinodis and Turbinaria ornata (brown macroalgae) were the most dominant macroalgal species. These macroalgae were identified at morphological and molecular (18s rRNA) levels. Then, the seasonal variations in macroalgal minerals and biochemical composition were quantified to determine the apt period for harvesting based on the nutritional requirements for commercial utilizations. The chemical composition of macroalgae proved the species and seasonal variation. For instance, minerals were more accumulated in macroalgae C. prolifera, A. spicifera and T. ornata in the winter season, but they were accumulated in both C. myrica and C. trinodis in the summer season. Total sugars, amino acids, fatty acids and phenolic contents were higher in the summer season. Accordingly, macroalgae collected during the summer can be used as food and animal feed. Overall, we suggest the harvesting of macroalgae for different nutrients and metabolites in the respective seasons.

Cement and oil refining industries as the predominant sources of trace metal pollution in the Red Sea: A systematic study of element concentrations in the Red Sea zooplankton

The Red Sea is exposed to metals from a large variety of natural and anthropogenic sources. In this study, we analyzed 19 common element concentrations in 14 Red Sea zooplankton samples using inductively coupled plasma-optical emission spectrometry (ICP-OES). The average metal or metalloid concentrations of the Red Sea zooplankton were: Ca > Sr > Fe > Al > Zn > As > Cu > Mn > Cr > Mo > Ni > Pb > Cd. The As, Ca, and Cu concentrations significantly increased with increasing latitude, while Cd concentrations decreased (p < 0.01). Our study indicated that anthropogenic activities (i.e., cement factories and oil refining industries) might be the predominant sources of significantly high Cr (1718 mg/kg), Fe (11,274 mg/kg), Mn (57.3 mg/kg), Mo (286 mg/kg), Ni (226 mg/kg), Pb (332 mg/kg), and Zn (17,046 mg/kg) concentrations that recorded in the Central to North Red Sea zooplankton.

Isolation and identification of marine Bacillus altitudinis KB1 from coastal Kerala: asparaginase producer

L-asparaginase is a target for many researchers as its properties against cancer, especially leukaemia, and protective agents reduce acrylamide in fried food. In this study, the water samples from Thumba Arattuvazhi Beach in Kerala were screened for l-asparaginase producing microorganisms. This was followed by colourimetric screening using modified M9 media with 0.009% Phenol red dye and using l-asparagine as a sole nitrogen source. Then, the Nessler assay was performed to quantify the enzyme. Molecular identification was made by 16SrRNA sequencing and aligned the sequence with GeneBank for phylogenetic tree construction using BLAST. Seawater was serially diluted for 10-1 to 10-6 using nutrient agar plates. A total of 19 bacterial colonies were isolated. The colonies were evaluated to produce l-asparaginase according to the pink zone around the colonies on the modified M9 medium using a red phenol indicator. The KB1 sample was selected for further studies according to plate colour assay. Nessler assay of L-asparaginase quantified as 2.537 IU/ml. Molecular characterisation showed the sequence association with Bacillus altitudinis the sequence submitted in Genebank as B. altitudinis KB1 strain. The l-asparaginase II gene (AnsB) was amplified based on the entire length of the hypothetical protein of annotated genome with accession number CP022319.2. The l-asparaginase activity in this study was 57% higher than the reference organism B. altitudinis BITHSP010. The l-asparaginase producing bacterium B. altitudinis KB1 from a marine source in Kerala can produce asparaginase, which can be utilised for biotechnology applications.

Taxonomic diversity of antimicrobial-resistant bacteria and genes in the Red Sea coast

Despite development of a record number of recreational sites and industrial zones on the Red Sea coast in the last decade, antibiotic-resistant bacteria in this environment remain largely unexplored. In this study, 16S rDNA sequencing was used to identify bacteria isolated from 12 sediment samples collected from the Red Sea coastal, offshore, and mangroves sites. Quantitative PCR was used to estimate the quantity of antimicrobial resistance genes (ARGs) in genomic DNA in the samples. A total of 470 bacteria were isolated and classified into 137 distinct species, including 10 candidate novel species. Site-specific bacterial communities inhabiting the Red Sea were apparent. Relatively, more resistant isolates were recovered from the coast, and samples from offshore locations contained the most multidrug-resistant bacteria. Eighteen ARGs were detected in this study encoding resistance to aminoglycoside, beta-lactam, sulfonamide, macrolide, quinolone, and tetracycline antibiotics. The qnrS, aacC2, ermC, and bla_TEM-1 genes were commonly found in coastal and offshore sites. Relatively higher abundance of ARGs, including aacC2 and aacC3, were found in the apparently anthropogenically contaminated (beach) samples from coast compared to other collected samples. In conclusion, a relative increase in antimicrobial-resistant isolates was found in sediment samples from the Red Sea, compared to other studies. Anthropogenic activities likely contribute to this increase in bacterial diversity and ARGs.

Production and Anticancer Activity of an L-Asparaginase from Bacillus licheniformis Isolated from the Red Sea, Saudi Arabia

Microbial L-asparaginase (ASNase) is an important anticancer agent that is used extensively worldwide. In this study, 40 bacterial isolates were obtained from the Red Sea of Saudi Arabia and screened for ASNase production using a qualitative rapid plate assay, 28 of which were producing large L-asparagine hydrolysis zones. The ASNase production of the immobilized bacterial cells was more favorable than that of freely suspended cells. A promising isolate, KKU-KH14, was identified by 16S rRNA gene sequencing as Bacillus licheniformis. Maximal ASNase production was achieved using an incubation period of 72 h, with an optimum of pH 6.5, an incubation temperature of 37 °C, an agitation rate 250 rpm, and with glucose and (NH4)2SO4 used as the carbon and nitrogen sources, respectively. The glutaminase activity was not detected in the ASNase preparations. The purified ASNase showed a final specific activity of 36.08 U/mg, and the molecular weight was found to be 37 kDa by SDS-PAGE analysis. The maximum activity and stability of the purified enzyme occurred at pH values of 7.5 and 8.5, respectively, with maximum activity at 37 °C and complete thermal stability at 70 °C for 1 h. The Km and Vmax values of the purified enzyme were 0.049995 M and of 45.45 μmol/ml/min, respectively. The anticancer activity of the purified ASNase showed significant toxic activity toward HepG-2 cells (IC50 11.66 µg/mL), which was greater than that observed against MCF-7 (IC50 14.55 µg/mL) and HCT-116 cells (IC50 17.02 µg/mL). The results demonstrated that the Red Sea is a promising biological reservoir, as shown by the isolation of B. licheniformis, which produces a glutaminase free ASNase and may be a potential candidate for further pharmaceutical use as an anticancer drug.

Heliomycin and tetracinomycin D: anthraquinone derivatives with histone deacetylase inhibitory activity from marine sponge-associated Streptomyces sp. SP9

Several actinomycetes strains were isolated from different marine sponges collected from the Red Sea shore in Egypt. The efficiency of their crude extracts to inhibit histone deacetylase (HDAC) enzyme was investigated in the nuclear extract of Hela cell line. The crude extract corresponding to Streptomyces sp. SP9 isolated from the marine sponge Pseudoceratina arabica showed a promising HDAC inhibitory activity with 64 and 81% at 50 and 100 µg/ml, respectively. The strain was identified as Streptomyces sp. by phylogenetic analyses based on its 16S rRNA gene sequence. The major compounds of Streptomyces sp. SP9 were isolated and purified by different chromatographic methods. The chemical structure of the isolated compounds was identified on the basis of their spectroscopic data including mass, ¹H and ¹³C NMR, and by comparison with those of authenticated samples. Structures of compounds 1 and 2 were established as heliomycin and tetracenomycin D, respectively. These compounds exhibited HDAC inhibitory activities with IC₅₀ values of 29.8 ± 0.04 µg/ml for heliomycin (1) and 10.9 ± 0.02 µg/ml for tetracenomycin D (2). A computational docking study for compounds 1 and 2 against HDAC1, HDAC2, and HDAC3 was performed to formulate a hypothetical mechanism by which the tested compounds inhibit HDAC. Tetracenomycin D (2) showed a good binding interactions with HDAC2 (- 5.230 kcal/mol) and HDAC3 (- 6.361 kcal/mol).

In Vivo Evaluation of the Toxic Effect of Ethyl Acetate Extracts of Marine Antibiotic Resistance Pseudomonas Species Derived from the Red Sea

Eighty-nine cultured Pseudomonas species isolated from the sediment and water samples collected from five industrial Red Sea regions that have been affected by petroleum and industry. Genotypic (exoT, exoS, exoU, exoY, lasA, lasB, rhlA, rhlB, Pf1, PAGI-1, -2, and -3) and phenotypic (DNase, elastase, lipase, protease, siderophore, antibiotic resistance patterns) characteristics were determined. Out of these isolates, nine Pseudomonas isolates were selected as the hyperactive virulence factors producers along with highly resistant pattern against all antibiotics of different classes included in this study. They were subjected to phenotypic and chemotypic characterization as well as molecular identification through 16S rRNA gene amplification and sequencing. The bioactive metabolites of these nine strains were extracted by ethyl acetate followed by evaluating their cytotoxic activity toward liver tissues, kidney tissues, and other biochemical activities in rat. Both EGY6 and EGY8 caused the highest significant reduction in the levels of packed cell volume (PCV), red blood cell count (RBC), and hemoglobin (Hb), which indicate that these Pseudomonas strain metabolites could cause anemia and toxic effects on hematological values in animals that were infected with them. Rats treated with the most toxic extract, EGY8, showed severe histopathological alterations in liver and kidney.

Viruses-to-mobile genetic elements skew in the deep Atlantis II brine pool sediments

The central rift of the Red Sea has 25 brine pools with different physical and geochemical characteristics. Atlantis II (ATIID), Discovery Deeps (DD) and Chain Deep (CD) are characterized by high salinity, temperature and metal content. Several studies reported microbial communities in these brine pools, but few studies addressed the brine pool sediments. Therefore, sediment cores were collected from ATIID, DD, CD brine pools and an adjacent brine-influenced site. Sixteen different lithologic sediment sections were subjected to shotgun DNA pyrosequencing to generate 1.47 billion base pairs (1.47 × 10⁹ bp). We generated sediment-specific reads and attempted to annotate all reads. We report the phylogenetic and biochemical uniqueness of the deepest ATIID sulfur-rich brine pool sediments. In contrary to all other sediment sections, bacteria dominate the deepest ATIID sulfur-rich brine pool sediments. This decrease in virus-to-bacteria ratio in selected sections and depth coincided with an overrepresentation of mobile genetic elements. Skewing in the composition of viruses-to-mobile genetic elements may uniquely contribute to the distinct microbial consortium in sediments in proximity to hydrothermally active vents of the Red Sea and possibly in their surroundings, through differential horizontal gene transfer.

The Egyptian Red Sea coastal microbiome: A study revealing differential microbial responses to diverse anthropogenic pollutants

The Red Sea is considered one of the youngest oceanic systems, with unique physical, geochemical and biological characteristics. Tourism, industrialization, extensive fishing, oil processing and shipping are extensive sources of pollution in the Red Sea. We analyzed the geochemical characteristics and microbial community of sediments along the Egyptian coast of the Red Sea. Our sites mainly included 1) four ports used for shipping aluminum, ilmenite and phosphate; 2) a site previously reported to have suffered extensive oil spills; and 3) a site impacted by tourism. Two major datasets for the sediment of ten Red Sea coastal sites were generated; i) a chemical dataset included measurements of carbon, hydrogen, nitrogen and sulfur, metals and selected semi-volatile oil; and ii) a 16S rRNA Pyrotags bacterial metagenomic dataset. Based on the taxonomic assignments of the 16S rRNA Pyrotags to major bacterial groups, we report 30 taxa constituting an Egyptian Red Sea Coastal Microbiome. Bacteria that degrade hydrocarbons were predominant in the majority of the sites, particularly in two ports where they reached up to 76% of the total identified genera. In contrast, sulfate-reducing and sulfate-oxidizing bacteria dominated two lakes at the expense of other hydrocarbon metabolizers. Despite the reported "Egyptian Red Sea Coastal Microbiome," sites with similar anthropogenic pollutants showed unique microbial community abundances. This suggests that the abundance of a specific bacterial community is an evolutionary mechanism induced in response to selected anthropogenic pollutants.

Metagenomic studies of the Red Sea

Metagenomics has significantly advanced the field of marine microbial ecology, revealing the vast diversity of previously unknown microbial life forms in different marine niches. The tremendous amount of data generated has enabled identification of a large number of microbial genes (metagenomes), their community interactions, adaptation mechanisms, and their potential applications in pharmaceutical and biotechnology-based industries. Comparative metagenomics reveals that microbial diversity is a function of the local environment, meaning that unique or unusual environments typically harbor novel microbial species with unique genes and metabolic pathways. The Red Sea has an abundance of unique characteristics; however, its microbiota is one of the least studied among marine environments. The Red Sea harbors approximately 25 hot anoxic brine pools, plus a vibrant coral reef ecosystem. Physiochemical studies describe the Red Sea as an oligotrophic environment that contains one of the warmest and saltiest waters in the world with year-round high UV radiations. These characteristics are believed to have shaped the evolution of microbial communities in the Red Sea. Over-representation of genes involved in DNA repair, high-intensity light responses, and osmoregulation were found in the Red Sea metagenomic databases suggesting acquisition of specific environmental adaptation by the Red Sea microbiota. The Red Sea brine pools harbor a diverse range of halophilic and thermophilic bacterial and archaeal communities, which are potential sources of enzymes for pharmaceutical and biotechnology-based application. Understanding the mechanisms of these adaptations and their function within the larger ecosystem could also prove useful in light of predicted global warming scenarios where global ocean temperatures are expected to rise by 1-3°C in the next few decades. In this review, we provide an overview of the published metagenomic studies that were conducted in the Red Sea, and the bio-prospecting potential of the Red Sea microbiota. Furthermore, we discuss the limitations of the previous studies and the need for generating a large and representative metagenomic database of the Red Sea to help establish a dynamic model of the Red Sea microbiota.