Selective carotenoid accumulation by varying nutrient media and salinity in Synechocystis sp. CCNM 2501 Chetan Paliwal, Imran Pancha, Tonmoy Ghosh, Rahulkumar Maurya, Kaumeel Chokshi, S.V. Vamsi Bharadwaj, Shristi Ram, Sandhya Mishra ⇑ Division of Salt & Marine Chemicals, CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, India Academy of Scientific & Innovative Research (AcSIR), CSIR-Central Salt and Marine Chemicals Research Institute Premises, Bhavnagar 364002, India highlights  Nutrients and salinity influence the carotenoid composition in microalgae.  Maximum carotenoid content in Synechocystis sp. CCNM 2501 is 7.99 mg g 1 DW.  >4 folds higher echinenone in Zarrouk’s media as compared to BG11 and Chu’s 10.  >3 folds higher b-carotene in 1 M salinity compared with non saline medium. graphical abstract article info Article history: Received 5 August 2015 Received in revised form 25 August 2015 Accepted 27 August 2015 Available online 31 August 2015 Keywords: Salinity Carotenoid Productivity Cyanobacteria abstract Nutrients are the deciding factors in the biological production of bioactive compounds. Various growth media like BG11, Zarrouk’s and Chu’s 10 were studied for carotenoid production in Synechocystis sp. CCNM 2501. Maximum carotenoid content (dry weight basis) was found in Zarrouk’s medium (ZM, 7.99 mg g 1 ) followed by BG11 (5.13 mg g 1 ). Echinenone content was 4 times higher in ZM (3.81 mg g 1 ) as compared to BG11 (0.95 mg g 1 ) and Chu’s 10 (0.77 mg g 1 ). Being an economical medium, BG11 was selected for carotenoid production. Further, increase in salinity from 0 to 0.2 M in BG11 medium increases total carotenoid content from 5.82 to 7.05 mg g 1 and later it declines to 6.23 mg g 1 (1 M). 3 times more b-carotene is produced at 1 M salinity as compared to control BG11. The variation in carotenoid composi- tion with change in nutrients/salinity can be a good strategy to enhance certain targeted carotenoids. Ó 2015 Published by Elsevier Ltd. 1. Introduction Nowadays, there is widespread public interest toward health concerns and hence, there is a race for extraction of novel bioactive compounds to be used as natural nutraceutical ingredients (Market and Market, 2014). Carotenoids are group of such omnipresent bioactive compounds which can be synthesized by all photosynthetic and some non-photosynthetic organisms. 40 carbon chain length and a vast structural diversity within a system of conjugated double bonds make this class of molecules phenom- enal radical scavengers. Carotenoids can be primary or secondary; primary carotenoids function as accessory light harvesting pigments and are essential for survival while the secondary ones are produced under stress (Guedes et al., 2011). They are crucial molecules for hunting down reactive oxygen species (ROS) and photo-protection via thermal dissipation of the excess light energy absorbed during photosynthesis. These naturally found carote- noids are of great interest due to their pharmaceutical, cosmetic and food applications. Some of these carotenoids are also efficient http://dx.doi.org/10.1016/j.biortech.2015.08.122 0960-8524/Ó 2015 Published by Elsevier Ltd. ⇑ Corresponding author at: Division of Salt & Marine Chemicals, CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, India. Tel.: +91 278 256 5801/256 3805x6160; fax: +91 278 256 6970/256 7562. E-mail address: smishra@csmcri.org (S. Mishra). Bioresource Technology 197 (2015) 363–368 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech