Selection and evaluation of CO_2 tolerant indigenous microalga Scenedesmus dimorphus for unsaturated fatty acid rich lipid production under different culture conditions

摘要

Five indigenous microalgal strains of Scenedesmus, Chlorococcum, Coelastrum, and Ankistrodesmus genera, isolated from Indian fresh water habitats, were studied for carbon-dioxide tolerance and its effect on growth, lipid and fatty acid profile. Scenedesmus dimorphus strain showed maximum growth (1.5g/L) and lipid content (17.83% w/w) under CO_2 supplementation, hence selected for detailed evaluation. The selected strain was alkaline adapted but tolerated (i) wide range of pH (5-11); (ii) elevated salinity levels (up to 100mM, NaCl) with low biomass yields and increased carotenoids (19.34mg/g biomass); (iii) elevated CO_2 levels up to 15% v/v with enhancement in specific growth rate (0.137d-1), biomass yield (1.57g/L), lipid content (19.6% w/w) and CO_2 biofixation rate (0.174gL-1d-1). Unsaturated fatty acid content (alpha linolenic acid) increased with CO_2 supplementation in the strain.