This study presents a comparative analysis of halophiles from the global open sea and coastal biosystems through shotgun metagenomes (n = 209) retrieved from public repositories. The open sea was significantly enriched with Prochlorococcus and Candidatus pelagibacter. Meanwhile, coastal biosystems were dominated by Marinobacter and Alcanivorax. Halophilic archaea Haloarcula and Haloquandratum, predominant in the coastal biosystem, were significantly (p < 0.05) enriched in coastal biosystems compared to the open sea. Analysis of whole genomes (n = 23,540), retrieved from EzBioCloud, detected crtI in 64.66% of genomes, while cruF was observed in 1.69% Bacteria and 40.75% Archaea. We further confirmed the viability and carotenoid pigment production by pure culture isolation (n = 1351) of extreme halophiles from sediments (n = 410 × 3) sampling at the Arabian coastline of India. All red-pigmented isolates were represented exclusively by Haloferax, resistant to saturated NaCl (6 M), and had >60% G + C content. Multidrug resistance to tetracycline, gentamicin, ampicillin, and chloramphenicol were also observed. Our study showed that coastal biosystems could be more suited for bioprospection of halophiles rather than the open sea.
Keywords: Haloferax; carotenoid; haloarchaea; halophiles; microbial pigments.