A novel native bioenergy green alga can stably grow on waste molasses under variable temperature conditions

Abstract

A novel bioenergy-producing green alga (lab ID.: XNY8011) was isolated from a local mountain in Beijing, China, and was identified as a strain belonging to the genus of Coelastrum on the basis of morphological and molecular characterization. Physiological analyses of photobiological H2 and lipid production suggested that XNY8011 could be a candidate for biofuels production. This strain could accumulate considerable biomass and produce massive chlorophylls in water diluted waste molasses. Three concentrations of molasses (0.1, 0.2 and 0.5%, w/v) were studied to optimize the cell growth and chlorophylls synthesis of XNY8011, and 0.2% was proved to be the optimum, in which XNY8011 could reach A600 of 1.55 ± 0.06 and produce 11.35 ± 0.93 μg/mL of chlorophylls. It was found that 25 °C is the most preferable temperature for the cell growth of XNY8011 in molasses. Interestingly, the strain XNY8011 exhibited significant low temperature adaptability when growing in waste molasses compared to typical bioenergy green algae. It produced 5.73 and 3.05 folds of cell densities in molasses than that Chlamydomonas reinhardtii CC503 and Chlorella vulgaris did under 20 °C, respectively, and even obtained 13.51 and 2.72 folds of cell densities under 15 °C, respectively. The dynamic analysis suggested that the sugar in waste molasses was utilized as carbon source for cell growth and biomass accumulation. The present study isolated a novel bioenergy-producing green alga from the native environment which could convert waste molasses to biomass and bioenergy with significant temperature adaptability.