Identification of Newly Zeaxanthin-Producing Bacteria Isolated from Sponges in the Gulf of Thailand and their Zeaxanthin Production

Sponge-associated bacteria have been found to produce a variety of bioactive compounds including natural pigments. Here, we report the molecular identification of zeaxanthin-producing sponge-associated bacteria isolated from sponges in the Gulf of Thailand and the effect of environmental factors on zeaxanthin production from a bacterium. Three colorful sponge-associated bacteria (CHOB06-6, KODA19-6, and MAKB08-4) were identified based on the 16S rDNA profile. The 16S rDNA sequence-based analyses revealed that CHOB 06-6 and MAKB 08-4 were the closest relatives to Sphingomonas phyllosphaerae FA2^T, and KODA19-6 was a relative of Shingomonas (Blastomonas) natatoria DSM 3183^T. After all bacteria were cultivated in a modified Zobell medium, S. natatoria KODA19-6 was found to produce the highest zeaxanthin at 0.62?mg/l. pH and temperature considerably affected its zeaxanthin production. Its optimal condition for zeaxanthin production was found at a pH of 7 and 30?°C. The bacterium had a maximum specific growth rate (?? _max) of 0.06?1/h with zeaxanthin productivity (Q _p) of 6.27???g/l·h. Therefore, this newly zeaxanthin-producing bacterium has a potential to produce natural zeaxanthin for the food, feed, pharmaceutical, and cosmetic industries.