Cells of Dunaliella salina from the log phase of growth were broken by sonication on ice-water-bath and the chloroplasts were isolated by centrifugation through sucrose gradient. Osmolarity of the growth medium, the suspending medium and the sucrose gradient was kept identical to minimize changes in chloroplast volume and mitochondrial entrapment. The isolated intact chloroplasts were stable to washing with buffered medium. Isolated chloroplast yield and purity was dependent on cell culture condition; a cycle of 16 hours light and 8 hours dark with continuous high CO2 was optimum. Isolated chloroplasts were about 70% intact by microscopic examination. The enzyme activity of glycerol-3-phosphate dehydrogenase was well retained in isolated chloroplasts.
