Journal of Agricultural Science; Vol. 13, No. 10; 2021 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 115 Influence of Sulphate Nutrition on Growth Performance and Antioxidant Enzymes Activities of Spirulina platensis Pierre Fils Rodrigue Magwell 1,3 , Emile Minyaka 1 , Oscar Wamba Fotsop 2 , Marlyse Solange Leng 1 & Léopold Gustave Lehman 4 1 Biochemistry Laboratory, Faculty of Science, University of Douala, Douala, Cameroon 2 Laboratory of Plant Biology, Faculty of Science, University of Douala, Douala, Cameroon 3 Institute of Agricultural Research for Development, Nko’olong Station, Kribi, Cameroon 4 Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, Douala, Cameroon Correspondence: Emile Minyaka, Biochemistry Laboratory, Faculty of Science, University of Douala, P.O. Box 24157 Douala, Cameroon. Tel: 237-674-071-671. E-mail: minyakae@yahoo.fr Received: December 8, 2020 Accepted: February 15, 2021 Online Published: September 15, 2021 doi:10.5539/jas.v13n10p115 URL: https://doi.org/10.5539/jas.v13n10p115 Abstract The growth of Spirulina platensis is dependent on culture conditions. This study has established adequate conditions for the quality and quantity production of S. platensis. The effect of sulphate salts nutrition on growth performance and biochemical status of S. platensis was assessed in vitro. Prior to culture, the Paracas strain of S. platensis from SAGRIC pond was analysed in different magnesium sulphate (MgSO 4 ; 0.08, 0.16, 0.32, 0.64 and 1.28 g/L), potassium sulphate (K 2 SO 4 ; 0.08, 0.16, 0.32, 0.64 and 1.28 g/L) and MgSO 4 /K 2 SO 4 (0.16/0.00, 0.08/0.08, 0.04/0.12, 0.02/0.14 and 0.01/0.15 g/L) concentrations. Culture media pH, total dissolved solids (TDS) and conductivity rate were monitored. Microscopic analysis revealed sulphate salt concentrations influenced the number of whorls and filaments of S. platensis. K 2 SO 4 (1.28 g/L) produced the highest number of whorls and filaments. Moreover, pH level fluctuated by sulphate treatments. K 2 SO 4 (1.28 g/L) had a pH level of 8.77±0.01 (day 5 of culture incubation). TDS and conductivity rate, protein and cysteine contents increased with culture age and K 2 SO 4 concentration in a culture medium. Conversely, negative correlations between protein and cysteine contents were observed, and sugar content decreased. Sulphate salt type and concentrations affected polyphenol oxidase (PPO) and peroxidase (POD) activities. MgSO 4 /K 2 SO 4 (0.02/0.14 g/L) displayed the best PPO and POD activities. Both enzymes appeared to be negatively correlated to the decreasing sugar content. These results indicate growth performances and biochemical status of S. platensis are significantly improved with the adequate supplementation of sulphate salts (MgSO 4 and K 2 SO 4 ) in culture media. Keywords: Spirulina platensis, sulphate salts, growth, antioxidant activity 1. Introduction Spirulina platensis is a multicellular, filamentous and microscopic photosynthetic cyanobacterium commonly found in the brackish lakes of Central Africa and Mexico. S. platensis has been consumed for centuries by the Aztecs and bordering populations on Lake Chad (Shigekatsu et al., 2019). This microalgae is characterized by a high content of protein (including enzymes such as polyphenol oxidase and peroxidase) and high amounts of essential fatty acids, essential amino acids, minerals, vitamins (especially B12), polysaccharides and antioxidant pigments (chlorophyll, carotenoids, phycobiliprotein, phycocyanin and carotenoids) (Budiyono et al., 2014; Ben Amor et al., 2017; Jung et al., 2019; Fatemeh & Choopani, 2020). This microalgae is being studied, not only for its nutritional properties but also for its reported therapeutic properties related to its hypolipidemic effect (Al-Saman et al., 2020), protective effect against diabetes and obesity (Azabji-Kenfack et al., 2011; Gómez-Téllez et al., 2020), inhibitory effect on anemia and cancer (Abdel-Daim et al., 2013; Barakat et al., 2015), stimulatory effect on the immunological system (Ngo-Matip et al., 2015; Ama Moor et al., 2020), nephrotoxicity effect on pharmaceuticals and toxic metals and protective effect against harmful radiation (Mohan et al., 2006; Priyanka Yadav et al., 2019). Because of its multiple properties, the production of S. platensis has gained worldwide attention for use in human food supplements, animal feed and pharmaceuticals industries.