Growth medium standardization and thermotolerance study of the freshwater microalga Acutodesmus dimorphus—a potential strain for biofuel production

Abstract

Microalgal biomass seems to be one of the potential alternative feedstocks for the production of various types of biofuel. In the present study, first of all, suitable growth media and harvesting time were determined for the freshwater chlorophyte microalga Acutodesmus dimorphus. Cultivation of A. dimorphus in BG-11 medium for 15 days resulted in the highest biomass productivity with 24.60 % lipid and 22.78 % carbohydrate contents. Further, thermotolerance property of A. dimorphus was evaluated by heat stressing the cells at 45 °C and 50 °C up to 24 h and determining the cell mortality and pigment composition along with lipid and carbohydrate contents. Chlorophyll and carotenoid contents of cells significantly increased after heat stress at 45 °C. Increasing the heat stress from 8 to 24 h increased the dead cells by 3–4 % at both temperatures, which shows the thermotolerance of A. dimorphus. Lipid content of 27 % and carbohydrate content of 26–28 % even after 24 h of heat stress at 45 and 50 °C suggest A. dimorphus as a potential feedstock for biofuel production.