Bituminous coal and sodium hydroxide-pretreated seawater stimulates Spirulina (Arthrospira) maxima growth with decreased production costs Md. Abu Affan a,b, ⁎, Dae-Won Lee a , Seon-Mi Jeon a , Jae-Hoon Noh a , Soo-Jin Heo a , Chulhong Oh a , Heung-Sik Park a , Hisham Sulaiman A. Khomayis b , Do-Hyung Kang a, ⁎⁎ a Korea Institute of Ocean Science and Technology (KIOST), Ansan P.O. Box 29, Seoul 426-744, Republic of Korea b Department of Marine Biology, College of Marine Sciences, King AbdulAziz University, P. O. Box 80207, Jeddah 21589, Saudi Arabia abstract article info Article history: Received 13 May 2014 Received in revised form 9 October 2014 Accepted 23 October 2014 Available online 31 October 2014 Keywords: Bituminous coal NaOH Pretreated seawater Organic carbon Spirulina maxima Biomass production Spirulina is a photosynthetic cyanobacterium rich in protein, polyunsaturated fatty acids, minerals and vitamins. Spirulina spp. are produced in fresh water, although freshwater shortages and the high-cost of feed stock carbon limit Spirulina production. Thus, use of seawater with low-cost carbon should be evaluated. Conversely, Ca 2+ and Mg 2+ of natural seawater (NSW) cause milky turbidity and nutrient precipitation when used in Spirulina culture medium. Here, NSW was pretreated with bituminous coal and NaOH to sediment Ca 2+ and Mg 2+ and obtain total organic carbon (TOC)-enriched pretreated seawater supernatant (PSWS), which was used to formulate Spirulina maxima culture medium. Pretreatment of NSW with bituminous coal and NaOH showed Ca 2+ and Mg 2+ precipitation rates of 32.52% and 99.91%, respectively, while TOC increased 6.97-fold in PSWS compared to NSW. The PSWS was 90–93% of NSW by volume, excluding sediment. The dry biomass production was 1.55 and 1.57 g L -1 and the chlorophyll a content was 13.75 and 17.90 mg L -1 in SOT and formulated AKSM-2-1 media, respectively. The maximum specific growth rate (μ max day -1 ) and biomass productivity of S. maxima were 0.283 and 0.284 day -1 and 1.97 and 2.00 g L -1 day -1 in SOT and formulated media, respectively. The bio- chemical composition and phycocyanin content were similar in the biomass of both media. Biomass production costs were ca. threefold lower in formulated medium than SOT medium. Therefore, S. maxima can be produced at lower costs using NSW following our method. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Spirulina (Arthrospira), a 3.6-billion-year-old cyanobacterium, in- cludes various species of primitive unicellular blue green algae, such as Spirulina platensis and Spirulina maxima. Spirulina grows in shallow and highly alkaline water in tropical areas (Johnston, 1970; Zavarzin, 2001). For the last two to three decades, Spirulina has commonly been used as a safe food supplement. Spirulina is commercially cultivated as a human food supplement, an animal feed ingredient, and for pharma- ceutical uses because of its ability to produce compounds such as caro- tene and omega 3 and 6-polyunsaturated fatty acids (Alonso and Maroto, 2000). Spirulina cultivation offers many advantages over tradi- tional agriculture, such as a high protein biomass, the absence of pro- cessing by-products, suitability for arid or semi-arid areas of the world, and its ability to be cultured in saline water. The high cost of feed- stock CO 2 is the main obstacle to Spirulina biomass production, especially the large requirements of NaHCO 3 and Na 2 CO 3 to formulate the culture medium. Moreover, NaCl is required in SOT or Zarrouk's me- dium to ensure profuse growth of S. maxima, as it is a marine species (Aiba and Ogawa, 1977; Zarrouk, 1966). The majority of Spirulina farms produce S. platensis, a freshwater spe- cies. In Hawaii, Spirulina pacifica® has been developed from an S. platensis strain (Cyanotech, Kailua-Kona, HI). S. maxima is less well characterized than S. platensis, especially for its cultivation in seawater. However, with the shortage of freshwater becoming a serious environ- mental problem (Vorosmarty et al., 2000), as well as the high costs of Spirulina biomass production using current media such as Zarrouk's and SOT (because of their requirement for carbonic salts), alternative methods should be explored. Spirulina sp. has also been directly cul- tured in human urine in China and in effluents from wastewater treat- ment plants of pig farms in Korea to account for the shortage of freshwater and nutrient costs (Hong and Lee, 1993; Lun and Cheng, 2006). Previously, Spirulina spp. were cultured in NSW supplemented with anaerobic effluent in an outdoor raceway in Mexico; however, the turbidity persisted. Natural seawater (NSW) is freely available, and its chemical composition is highly variable; it contains 50 known ele- ments and many organic compounds that promote S. maxima growth (Gagneux et al., 2007). However, the use of typical NSW presents Aquaculture 436 (2015) 121–126 ⁎ Correspondence to: Md. Abu Affan, Department of Marine Biology, College of Marine Sciences, King AbdulAziz University, P. O. Box 80207 Jeddah 21589, Saudi Arabia. Tel.: +966 02 6952687; fax: +966 02 6401747. ⁎⁎ Corresponding author. Tel.: +82 31 400 7733; fax: +82 31 408 5934. E-mail addresses: affan2007@gmail.com (M. Abu Affan), dohkang@kiost.ac (D.-H. Kang). http://dx.doi.org/10.1016/j.aquaculture.2014.10.036 0044-8486/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aqua-online