Mixotrophic cultivation of Chlorella sp. BTA 9031 and Chlamydomonas sp. BTA 9032 isolated from coal field using various carbon sources for biodiesel production

• Chlorella sp. BTA 9031 and Chlamydomonas sp. BTA 9032 was isolated from coalfield.
• BG-11 substituted with 40% CWP was an effective and cheap media for algal growth.
• A notable specific growth rate of 1.21 d−1 was obtained for Chlorella sp. BTA 9031.
• Chlamydomonas sp. BTA 9032 accumulated total lipid of 38.66% using CWP.
• FAME analysis showed presence of fatty acids required for biofuel production.

In the present work feasibility of utilizing various carbon sources in enhancing the biomass and lipid productivity of two species Chlorella sp. BTA 9031 and Chlamydomonas sp. BTA 9032 isolated from Indian coalfields was investigated. Carbon dioxide (CO2), sodium acetate, sodium bicarbonate, fructose and two very cheap carbon sources were used namely, cheese whey permeate (CWP) and molasses. The biomass concentration obtained using CWP and molasses were higher than that obtained with refined carbon source, fructose and sodium acetate. Due to the presence of growth promoting factors present in CWP, highest biomass productivity of Chlorella sp. BTA 9031 and Chlamydomonas sp. BTA 9032 were 75 and 43 mg L−1 d−1 respectively. The highest total lipid (38.6%) was obtained in Chlamydomonas sp. BTA 9032 using CWP as a carbon source. In both the microalgal species C13:0, C14:0, C18:0, C14:1, C15:1, C17:1 and C20:0 were identified as the major FAMEs which are suitable to be used as biodiesel components. Hence, CWP could be served as an alternative carbon source for mixotrophic algae cultivation and biodiesel production.