Simultaneous Lipid Production and Valorization of Crude Glycerol by Mixotrophic and Heterotrophic Cultivation of Arthrospira platensis

Abstract

This study investigates the possible use of crude glycerol as external carbon source for mixotrophic and heterotrophic cultivation of Arthrospira platensis for the purpose of producing lipid. Recently, biodiesel has become a remarkable biofuel while cyanobacterial lipid is an alternative feedstock for biodiesel production. In this study effect of carbon source concentration, trophic culture type on production of biomass, chlorophyll, protein, total carbohydrate and lipid were examined. In terms of total lipid content, the highest value was detected as 5.78 ± 0.21 mg/g cell with 10 mM crude glycerol in mixotrophic cultivation on 18^th day. Higher specific growth rates were detected in mixotrophic cultures. The fatty acid composition was detected by gas chromatography. The produced lipid had the basic fatty acids for a quality biodiesel production — palmitic, stearic, oleic and linoleic acids. The biodiesel potential of produced lipid was investigated. The indicator of oxidative stability of the fuel, iodine value was in accordance with UNE-EN 14214. Cetane number and oxidative stability are related to productive combustion characteristics of fuel which comply with ASTM 6751 standards. These results show that the fatty acid composition of the produced lipid, from a waste material via economical fermentation, is suitable for a qualitative fuel production.