Microbial dynamics, chemical profile, and bioactive potential of diverse Egyptian marine environments from archaeological wood to soda lake.

Halophilic archaea are a unique group of microorganisms that thrive in high-salt environments, exhibiting remarkable adaptations to survive extreme conditions. Archaeological wood and El-Hamra Lake serve as a substrate for a diverse range of microorganisms, including archaea, although the exact role of archaea in archaeological wood biodeterioration remains unclear. The morphological and chemical characterizations of archaeological wood were evaluated using FTIR, SEM, and EDX. The degradation of polysaccharides was identified in Fourier transform infrared analysis (FTIR). The degradation of wood was observed through scanning electron microscopy (SEM). The energy dispersive X-ray spectroscopy (EDX) revealed the inclusion of minerals, such as calcium, silicon, iron, and sulfur, into archaeological wood structure during burial and subsequent interaction with the surrounding environment. Archaea may also be associated with detected silica in archaeological wood since several organosilicon compounds have been found in the crude extracts of archaeal cells. Archaeal species were isolated from water and sediment samples from various sites in El-Hamra Lake and identified as Natronococcus sp. strain WNHS2, Natrialba hulunbeirensisstrain WNHS14, Natrialba chahannaoensis strain WNHS9, and Natronococcus occultus strain WNHS5. Additionally, three archaeal isolates were obtained from archaeological wood samples and identified as Natrialba chahannaoensisstrain W15, Natrialba chahannaoensisstrain W22, and Natrialba chahannaoensisstrain W24. These archaeal isolates exhibited haloalkaliphilic characteristics since they could thrive in environments with high salinity and alkalinity. Crude extracts of archaeal cells were analyzed for the organic compounds using gas chromatography-mass spectrometry (GC-MS). A total of 59 compounds were identified, including free saturated and unsaturated fatty acids, saturated fatty acid esters, ethyl and methyl esters of unsaturated fatty acids, glycerides, phthalic acid esters, organosiloxane, terpene, alkane, alcohol, ketone, aldehyde, ester, ether, and aromatic compounds. Several organic compounds exhibited promising biological activities. FTIR spectroscopy revealed the presence of various functional groups, such as hydroxyl, carboxylate, siloxane, trimethylsilyl, and long acyl chains in the archaeal extracts. Furthermore, the archaeal extracts exhibited antioxidant effects. This study demonstrates the potential of archaeal extracts as a valuable source of bioactive compounds with pharmaceutical and biomedical applications.

Fabrication of environmentally safe antifouling coatings using nano-MnO2/cellulose nanofiber composite with BED/GMA irradiated by electron beam.

Marine biofouling, undesirable growth of organisms on submerged surfaces, poses significant challenges in various industries and marine applications. The development of environmentally safe antifouling coatings employing nano-MnO2/cellulose nanofiber (CNF) composite with bisphenol A epoxy diacrylate/glycidyl methacrylate (BED/GMA) irradiated by electron beam (T1) has been achieved in the current work. The physico-chemical characteristics of the fabricated coatings have been studied using Fourier transforms infrared spectroscopy, scanning electron microscope, water contact angle, and X-ray diffraction. The efficacy of T1 formulation and pure BED/GMA polymer (T2) in inhibiting biofouling formation was investigated in seawater of Alexandria Eastern Harbour by examining biofilm development morphologically and biochemically. In addition, regular analyses of seawater physicochemical parameters were conducted monthly throughout study. Results provide valuable information on coating performance as well as the complex interactions between coatings, biofilms, and environmental factors. The T1 formulation exhibited strong anti-fouling and anticorrosion properties over 2 months. However, after four months of immersion, all coated steel surfaces, including T1, T2, and T0, were heavily covered with macro-fouling, including tubeworms, barnacles, and algae. Biochemical analysis of extracellular polymeric substances (EPS) showed statistically significant variations in carbohydrates content between the coated surfaces. The T1 formulation showed decreased protein and carbohydrate content in EPS fractions after 14 days of immersion indicating less biofouling. Moreover, elemental analysis showed that carbon, oxygen, and iron were the predominant elements in the biofilm. Other elements such as sodium, silicon, chloride, and calcium were in lower concentrations. T2 and T0 surfaces revealed higher calcium levels and the appearance of sulphur peaks if compared with T1 surface. Diatoms and bacteria were detected on T1, T2, and T0 surfaces. The observed warming of seawater and nutrient-rich conditions were found to promote the growth of fouling organisms, emphasizing the importance of considering environmental factors in biofouling management strategies.

Isotherm and kinetic studies of cadmium biosorption and its adsorption behaviour in multi-metals solution using dead and immobilized archaeal cells.

It is crucial to identify more biological adsorbents that can efficiently uptake metals from wastewater. Dry haloalkaliphilic archaea Natronolimnobius innermongolicuswas evaluated for Cd ions biosorption. The optimal operating conditions (pH, biomass dose, initial metal concentration, contact time, and isotherms models) were tested. Biosorption process is influenced by the metal's solution pH with maximum removal of 83.36% being achieved at pH 8. Cadmium ions uptake reaches equilibrium in about 5 min of biosorption process. The Langmuir model was determined to better fit the Cd(II) biosorption by dry archaea. The maximal uptake capacity (qmax) of Cd(II) was 128.21 mg/g. The effect of multi-component system on biosorption behaviour of Pb, Ni, Cu, Fe, and Cd ions by immobilized dried archaeal cells, dried archaeal cells, and dried bryozoa was studied using Plackett-Burman experimental design. The investigated biosorbents were effective at removing metals from contaminated systems, particularly for Fe, Pb, and Cd ions. Moreover, the interaction behaviour of these metals was antagonistic, synergistic, or non-interactive in multi-metals system. SEM, EDX, and FTIR spectra revealed changes in surface morphology of the biomass through the biosorption process. Finally, continuous adsorption experiment was done to examine the ability of immobilized biomass to adsorb metals from wastewater.

Prevalence and risk assessment of microplastics in the Nile Delta estuaries: "The Plastic Nile" revisited.

Recent research is directed toward studying plastic pollution in rivers, and estuaries due to the importance of freshwater bodies in all aspects of life. The river deltas and estuaries are interesting for studying the flux of plastics into the oceans. The Nile River has been identified as a hot spot of plastic litter flux in the eastern Mediterranean basin. In addition, it was nicknamed "Plastic Nile", yet this major river is largely unexplored with a lack of field measurements and adequate surveys. The current study was based on bridging this scientific gap. Three trips were conducted, covering 30 km in the Rosetta branch and 23 km in the Damietta branch, during the high water level in summer 2021, and 10 km off the inlet of Lake Burullus, in spring 2021. Microplastics in surface water ranged from 761 ± 319 to 1718 ± 1008 MPs/m3, and from 167 ± 137 to 1630 ± 1303 MPs/kg of dry sediments. Land use/ land cover mapping using Sentinel-2 images showed several sources of pollution that contribute to plastic contamination in the study area. Thermal analysis indicated seven plastic polymers; including, PE, PP, PET, PEVA, and PTFE, using discarded plastic products as reference materials. Microplastics were composed of colored and glossy fragments of sizes <500 µm, originating from land-based sources. Pollution load, polymer risk assessment, and ecological risk indices were calculated. Based on field observations macro-plastics were retained within the extensive network of infrastructure and dam systems. 80-106 billion MPs/year were estimated to flux from the Nile estuaries into the Mediterranean Sea. The current situation urges the development of binding plans to reduce plastic waste in the Nile Delta, as well as setting environmental monitoring points along the Deltaic coast.