---

Aims: Carotenoids are a vast group of lipid-soluble pigments, which are produced by variety of microorganisms. The aim of this study was to compare the production of carotenoid pigments by prokaryotic isolates of Iranian saline ecosystems and identify superior isolate.
Materials & Methods: In this the experimental study, isolates were purified by culture-based methods and carotenoid extracts were analyzed by spectrophotometry in wavelength region of 400nm to 600nm. The total carotenoid content was estimated by spectrophotometry at λ_max (490nm). Identity of bands was detremined by purification of bands by Thin Layer Chromatography (TLC) and analysis by High Pressure Liquid Chromatography (HPLC) and Fourier Transform Infrared Spectroscopy (FTIR).
Findings: Fourty-three isolates were obtained. Eight isolates were halotolerant bacteria, 8 isolates were moderately halophile, and 27 isolates were extremely halophile. All of the strains were capable of producing carotenoid compounds. Isolate M24 with 2054μg/g production was selected as superior isolate. Thin layer chromatography exhibited 6 colored bands in colored extract of this strain and the most concentrated band was purified. After purification by TLC and HPLC, spectrophotometry in UV range showed two pics at 530nm and 465nm as the highest absorbances, which were similar to UV absorbance of α-bacterioruberin. Phylogenetic analysis of 16S rRNA gene sequence of strain M24 showed that this strain had 98% similarity with Haloarcula amylolytica BD-3.
Conclusion: From Iranian Saline Ecosystems, 43 isolates are obtained. Eight isolates are halotolerant bacteria, 8 isolates are moderately halophile, and 27 isolates are extremely halophile. All of the isolates are capable of producing carotenoid compounds. Strain M24 is superior isolate, having 98% similarity with Haloarcula amylolytica BD-3.