Biochemical and Molecular Characterization of Carotenogenic Flavobacterial Isolates from Marine Waters

Carotenoids are known to possess immense nutraceutical properties and microorganisms are continuously being explored as natural source for production of carotenoids. In this study, pigmented bacteria belonging to Flavobacteriaceae family were isolated using kanamycin-containing marine agar and identified using the molecular techniques and their phenotypic characteristics were studied along with their potential to produce carotenoids. Analysis of random amplification of polymorphic DNA (RAPD) banding patterns and the fragment size of the bands indicated that the 10 isolates fall under two major groups. Based on 16S rRNA gene sequence analysis the isolates were identified as Vitellibacter sp. (3 isolates), Formosa sp. (2 isolates) and Arenibacter sp. (5 isolates). Phenotypically, the isolates showed slight variation from the reported species of these three genera of Flavobacteriaceae. Only the isolates belonging to Vitellibacter and Formosa produced flexirubin, a typical yellow orange pigment produced by most of the organisms of the family Flavobacteriaceae. Vitellibacter sp. and Formosa sp. were found to produce higher amount of carotenoids compared to Arenibacter sp. and zeaxanthin was found to be the major carotenoid produced by these two species. The study indicated that Vitellibacter sp. and Formosa sp. can be exploited for production of carotenoids, particularly zeaxanthin.