Isolation and characterization of yellow pigment producing Exiguobacterium sps.

Thirteen yellow pigment producing bacterial strains were isolated by air and soil sampling method and screened for carotenoid production, as many of them exhibited a deep orange pigmentation when cultured on NA-plates. We found that most of them produced trace amount of carotenoids. The isolates RS7, RSS3, RS13 and RS14 had significant amounts of the yellow pigment producing ability (Degree of pigmentation 8.31, 2.72, 6.66 and 5.5). Free Radical Scavenging Activity of the extracts from the isolates were analyzed by DPPH (1, 1-Diphenly-2-picryl-hydrazil) method. Isolate RS7 showed maximum free radical scavenging activity (72%). HPLC result revealed that the isolated strains are the natural producer of Astaxanthin. Based on the Biochemical characterization and 16S rDNA gene sequencing analysis, out of the four isolates two of them (RS7 and RS13), were identified as Exiguobacterium aurantiacum and the other two isolates (RSS3 and RS14) as Exiguobacterium profundum.