Growth and Lipid Production from Scenedesmus sp. Under Mixotrophic Condition for Bioenergy Application

Abstract

Microalgae are seen as an alternative and renewable feedstock for biodiesel production. They are effective in producing large amount of oil which can be converted into biodiesel by the process of transesterification. The present work aims to cultivate microalgae under optimized culture condition and lipid was extracted for the production of fatty acid methyl esters (FAMEs). The biomass and lipid content of the species was tried to enhance under photoheterotrophic (mixotrophic) condition by adding glycerol as the organic carbon source. Glycerol is the by-product in transesterification reaction for biodiesel production, its utilization in algae cultivation will support the biorefinery system. The green microalgae, Scenedesmus sp. was cultured in Fogg’s medium and culture conditions were optimized for best growth. The algae were allowed to grow mixotrophically with glycerol at concentrations ranging from 0–5 % (v/v) and significant improvement was noticed in growth and lipid accumulation. The growth of the Scenedesmus sp. was increased up to 1 % glycerol (v/v) and recorded 0.414 g l⁻¹ that is approximately 2 times in comparison with photoautotrophic cultivation (0.223 g l⁻¹). The lipid accumulation of 36.47 % was estimated in cultures with 1 % glycerol which is, nearly, 3 times that of autotrophic culture (12.55 %). Maximum lipid accumulation (52.32 %) was achieved under mixotrophic cultivation using 5 % glycerol, but growth is inhibited at very high concentration. Oil from Scenedesmus sp. grown under 1 % glycerol was subjected to acid-based transesterification for its proposed application in biofuel. The lipid enhancement in Scenedesmus sp. in the presence of glycerol provides a potential route for economic biodiesel production.