Haloferax (common abbreviation: Hfx.) is a genus of halobacteria in the order Haloferacaceae.
Cells of H. mediterranei and cells of the related species H. volcanii can undergo a process of genetic exchange between two cells which involves cell fusion resulting in a heterodiploid cell (containing two different chromosomes in one cell). Although this genetic exchange ordinarily occurs between two cells of the same species, it can also occur at a lower frequency between an H. mediterranei and an H. volcani cell. These two species have an average nucleotide sequence identity of 86.6%. During this exchange process, a diploid cell is formed that contains the full genetic repertoire of both parental cells, and genetic recombination is facilitated. Subsequently, the cells separate, giving rise to recombinant cells.
As of 2022, 13 species are validly published under the genus Haloferax.
Several species and novel binomial names have been proposed, but not validly published.
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI).
Unassigned Haloferax:
Several Haloferax species, especially Haloferax mediterranei have gained eminence for their ability to serve as an efficient chassis for bioproduction. H. mediterranei is a well-known producer of polyhydroxyalkanoates, a sustainable and biodegradable bioplastic. They have been studied for the production of several value-added products such as bioplastics, pigments and exoenzymes. H. mediterranei is capable of accumulating high amounts of both homopolymer PHAs and co-polymer PHAs from a wide array of sustainable carbon substrates. Haloferax species have also been used to produce industrially relevant exoenzymes such as laccase for bioprocessing. Since they can thrive in extreme conditions of salinity, toxicity, heavy metal exposure and UV radiation, the fermentation costs are significantly lowered as the chance of contamination is reduced. In hypersaline environments like the Dead Sea & Great Salt Lake, Haloferax species shoulder most of the responsibility of denitrification. These strains could be leveraged for nitrogen removal systems designed to remediate saline effluents from fisheries, textile industries and food processing plants.