ISOLATION AND CHARACTERIZATION OF CHLORELLA SOROKINIANA GXNN01 (CHLOROPHYTA) WITH THE PROPERTIES OF HETEROTROPHIC AND MICROAEROBIC GROWTH(1).

Heterotrophic and anaerobic microalgae are of significance in both basic research and industrial application. A microalga strain was isolated from a wastewater treatment pond and identified as Chlorella sorokiniana Shihira et W. R. Krauss GXNN01 in terms of morphology, physiology, and phylogeny. The strain grows rapidly in heterotrophic or mixotrophic conditions with addition of various carbon sources, and even in anaerobic conditions. The maximum growth rate reached 0.28 d(-1) when using d,l-malate as the carbon source, and the protein content of the microalgae was 75.32% in cell dry weight. The strain was shown to be capable of (1) utilizing d,l-malate only with light, (2) inhibiting photosynthesis in mixotrophic growth, and (3) growing in anaerobic conditions with regular photosynthesis and producing oxygen internally. This study demonstrates the influence of oxygen (aerobic vs. anaerobic) and metabolic regime (autotrophy, mixotrophy, heterotrophy) on the physiological state of the cell.