Extremophilic Exopolysaccharides: Biotechnologies and Wastewater Remediation

Various microorganisms thrive under extreme environments, like hot springs, hydrothermal vents, deep marine ecosystems, hyperacid lakes, acid mine drainage, high UV exposure, and more. To survive against the deleterious effect of these extreme circumstances, they form a network of biofilm where exopolysaccharides (EPSs) comprise a substantial part. The EPSs are often polyanionic due to different functional groups in their structural backbone, including uronic acids, sulfated units, and phosphate groups. Altogether, these chemical groups provide EPSs with a negative charge allowing them to (a) act as ligands toward dissolved cations as well as trace, and toxic metals; (b) be tolerant to the presence of salts, surfactants, and alpha-hydroxyl acids; and (c) interface the solubilization of hydrocarbons. Owing to their unique structural and functional characteristics, EPSs are anticipated to be utilized industrially to remediation of metals, crude oil, and hydrocarbons from contaminated wastewaters, mines, and oil spills. The biotechnological advantages of extremophilic EPSs are more diverse than traditional biopolymers. The present review aims at discussing the mechanisms and strategies for using EPSs from extremophiles in industries and environment bioremediation. Additionally, the potential of EPSs as fascinating biomaterials to mediate biogenic nanoparticles synthesis and treat multicomponent water contaminants is discussed.

ELEMENTAL ANALYSIS OF RAINWATER BY PIXE TECHNIQUE

Analysis of trace and toxic metals in untreated rainwater has been carried out using nondestructive proton induced X-ray emission (PIXE) in combination with pre-concentration technique. The pre-concentration technique used for this purpose was carried out by evaporation of the rainwater samples at 50°C under atmospheric pressure. Untreated rainwater samples were collected from 10 different locations across Baghdad city, Iraq. The mean concentration values of the elements ( Al, Ca, Co, Ti, V, Cr, Mn, Fe, Zn, Br, Rb and Sr ) in rainwater samples were determined simultaneously at the parts per billion (ppb) levels. The rainwater samples and certified reference materials (CRMs) were irradiated with 2.0 MeV proton beam from Van de Graaff accelerator. The accuracy of the results was proved by using certified reference materials (GSP-2). The results were compared with the published data, Iraqi standards (IRQ), European standards (EU), and World Health Organization (WHO) guidelines for drinking water quality. The purpose of this work was to obtain the total elemental compositions of rainwater in Iraq.