Cultivation and characterization of haloarchaea from Moroccan Atlantic solar salterns: insights into diversity and bioactive potential.

This study provides the first culture-based inventory of haloarchaeal diversity in Moroccan Atlantic solar salterns (Oualidia and Khenifiss), using sediment samples collected across a gradient of moderate to high salinity (16.7–29.2% w/v) and slightly alkaline pH (7.4–7.5). A total of 69 representative isolates were phylogenetically assigned to nine genera within five families of the class Halobacteria. Both sites shared a core assemblage in which Halorubrum, Haloarcula, Haloferax, and Natrinema were the most frequently isolated taxa, whereas low-frequency genera (Halobacterium, Halogeometricum, Halococcus, Halomicrobium, and Halostagnicola) displayed differences in isolate recovery between sites, given the culture-dependent nature of the approach, no direct inference on in situ community structuring can be drawn. Several isolates display relatively low 16 S rRNA (< 98.65%) gene sequence similarity to validly published type strains and therefore constitute candidates for future genome-based taxonomic assessment. Standardized antagonism assays revealed inhibitory activity within and between sites, with Natrinema and Haloferax displaying the broadest inhibitory spectra. Collectively, these results provide new baseline data for Atlantic hypersaline sediments and highlight these environments as reservoirs of phylogenetically and functionally diverse extremophilic microorganisms.