**5. Summary and future perspective**

Extensive research was conducted in the past for denitrifiers in treating municipal wastewater which typically contains TDS less than 1000 mg/L. Whether the knowledge acquired in regard to the stoichiometry, kinetics, metabolic pathways, and microbial communities and characteristics is transferrable to halophilic counterparts is subject to further research.

Through the above short review, it was suggested that specific denitrification rates of mixed cultures decreased with an increasing salinity concentration. However, some specific species such as *H. campisalis* sp. *nov*. exhibited relatively high denitrification rates at 12.5% salinity with different carbon sources, similar to that of its freshwater counterparts. If biomass is properly acclimated and adapted to saline environments, the SDNR could be comparable to that at low-salinity concentrations.


**Table 3.** Summary of halophilic denitrifying species.
