Carotenoid Nostoxanthin Production by <i>Sphingomonas</i> sp. SG73 Isolated from Deep Sea Sediment

• Main Authors: Hiroshi Kikukawa, Takuma Okaya, Takashi Maoka, Masayuki Miyazaki, Keita Murofushi, Takanari Kato, Yoko Hirono-Hara, Masahiro Katsumata, Shoichi Miyahara, Kiyotaka Y. Hara
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Marine Drugs
• Subjects: carotenoid; nostoxanthin; <i>Sphingomonas</i>; deep sea microorganism
• Online Access: https://www.mdpi.com/1660-3397/19/5/274

Carotenoids are used commercially for dietary supplements, cosmetics, and pharmaceuticals because of their antioxidant activity. In this study, colored microorganisms were isolated from deep sea sediment that had been collected from Suruga Bay, Shizuoka, Japan. One strain was found to be a pure yellow carotenoid producer, and the strain was identified as <i>Sphingomonas</i> sp. (Proteobacteria) by 16S rRNA gene sequence analysis; members of this genus are commonly isolated from air, the human body, and marine environments. The carotenoid was identified as nostoxanthin ((2,3,2′,3′)-β,β-carotene-2,3,2′,3′-tetrol) by mass spectrometry (MS), MS/MS, and ultraviolet-visible absorption spectroscopy (UV-Vis). Nostoxanthin is a poly-hydroxy yellow carotenoid isolated from some photosynthetic bacteria, including some species of Cyanobacteria. The strain <i>Sphingomonas</i> sp. SG73 produced highly pure nostoxanthin of approximately 97% (area%) of the total carotenoid production, and the strain was halophilic and tolerant to 1.5-fold higher salt concentration as compared with seawater. When grown in 1.8% artificial sea salt, nostoxanthin production increased by 2.5-fold as compared with production without artificial sea salt. These results indicate that <i>Sphingomonas</i> sp. SG73 is an efficient producer of nostoxanthin, and the strain is ideal for carotenoid production using marine water because of its compatibility with sea salt.