Novel β-Carotene and Astaxanthin-Producing Marine Planococcus sp.: Insights into Carotenogenesis Regulation and Genetic Aspects.

Astaxanthin and β-carotene are the most prominent carotenoids extensively used in pharmaceutics. Here, we present a halotolerant bacterium from Lake Wadi El-Natrun capable of producing astaxanthin and β-carotene analyzed by HPLC, ESI-MS, and infrared spectroscopy. The phenotypic and phylogenetic analyses classified the isolate as a novel strain of the genus Planococcus, for which the name Planococcus sp. Eg-Natrun is proposed. Carotenoid biosynthesis can exceptionally occur in a light-inducible or constitutive manner. The maximum carotenoid yields were 610 ± 13 µg/g (~ 38% β-carotene and ~ 21% astaxanthin) in a minimal medium with acetate and 1024 ± 53 µg/g dry cells in a rich marine medium. The carotenogenesis incentives (e.g., acetate) and disincentives (e.g., methomyl) were discussed. Moreover, we successfully isolated the CrtE gene, one of the astaxanthin biosynthesis genes, from the unknown genome using a consensus-based degenerate PCR approach. To our knowledge, this is the first report elucidating astaxanthin and β-carotene in the genus Planococcus.