Haloarchaea, excellent candidates for removing pollutants from hypersaline wastewater

Hypersaline wastewater is difficult to treat due to the inhibition of salt stress on microbes’ viability and metabolic capabilities. Haloarchaea, native microorganisms that thrive in hypersaline habitats, overcome this key obstacle naturally. This review provides a comprehensive overview of the metabolic versatility of Haloarchaea in hypersaline wastewater treatment, including carbon, nitrogen, phosphorus, sulfur, and heavy metal metabolism. It also analyzes factors affecting pollutant removal and addresses metabolic mechanisms. Additionally, haloarchaea microbial characteristics and strategies to cope with salt stress are highlighted. Finally, the biotechnological potential of biomolecules produced from haloarchaea is investigated. To get better insight into the potential of haloarchaea, a deeper investigation of basic metabolism and more in-depth studies of their genomics and applications in actual wastewater are also necessary. Haloarchaea are excellent candidates to treat hypersaline wastewater because they show an extensive metabolic versatility of carbon, nitrogen, phosphorus, sulfur, and heavy metal.The ‘salt-in’ strategy, mainly the accumulation of K+ and expulsion of Na+, is used by haloarchaea to cope with salt stress.Haloarchaea have special features and biomolecules, such as haloarchaeal enzymes, gas vesicles, and poly-β-hydroxyalkanoates, that make them worth exploring for their biotechnological and industrial potential.The discovery of polyextremophilic (halophilic, thermophilic, and alkaliphilic) haloarchaea promotes their real-world applications in wastewater treatment under multiple stresses.