Sustainable production of biomass and biodiesel by acclimation of non-acidophilic microalgae to acidic conditions

• DOI: 10.1016/j.biortech.2018.09.140
• Publication Date: 2018-09-29T18:18:07Z
• Authors: Sudharsanam Abina...; Suresh R. Subashc...; Nicole Cole; Rajarathnam Dharm...; Kadiyala Venkates...; Mallavarapu Megharaj
• Keywords: 0301 basic medicine; Esterification; microalgae; Acclimatization; biodiesel; acclimation; Flow Cytometry; Lipid Metabolism; Lipids; 7. Clean energy; 01 natural sciences; non-acidophiles; 333; biochemical response; 12. Responsible consumption; lipids; 03 medical and health sciences; Chlorophyceae; 13. Climate action; Biofuels; Biomass; Reactive Oxygen Species; 0105 earth and related environmental sciences

The overwhelming response towards algal biodiesel production has been well-recognized recently as a sustainable alternative to conventional fuels. Most microalgae cannot grow well at acidic pH. The present study, therefore, investigated whether non-acidophilic microalgae Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3 can be acclimated to extreme-acidic pH for sustainable production of biomass and biodiesel. Growth analysis indicated that both the microalgal strains possessed a passive uptake of CO2 at pH 3.0 with biomass production of 0.25 g dry wt. L-1 in Desmodemus sp. and 0.45 g dry wt. L-1 in Heterochlorella sp.. Flow-cytometry analysis for reactive oxygen species, membrane permeability and neutral-lipids revealed the capabilities of both strains to adapt to the stress imposed by acidic pH. Lipid production was doubled in both the strains when grown at pH 3.0. In-situ transesterification of biomass resulted in 13-15% FAME yield in the selected microalgae, indicating their great potential in biofuel production.