Effect of light sources on hydrogen production and metsbolish of Platymonas subcordiformis

The effect of light sources (white ,red and blue lights)was studied upon growth. Primary metabolism and hydrogen production of marine green algae platymonas Subcordiformis .White and red lights are beneficial to cell grown ,with higher specific growth rate and shorter lag growth phase .The culture PH increased form 8.5 to 10 within 3-5days and decrease gradually thereafter .The lowest PH was observed for the cultivation under blue light,indicating a strong anaerobic fermentation activity .Intracellular water—soluble polysaccharides(IWSPs)increase concomitantly with algal cell growth ,which continue to accumulate during stationary and decline phase .Intracellular water—soluble proteins(IWSP) decrease during the active cell growth phase and then increase after the cell density reached the maximum at the end of exponential growth phase .In contrast with the production of IWSPs ,the lowest level of IWSP was obtained under red light .No significant change in chloroplast level was observed until the late exponential growth phase .The level of chloroplast decreased significantly during stationary phase and increased to a steady level during decline phase .The highest level of chloroplast was obtained under blue light .The algal cells cultivated under three lights sources were subjected to photo –hydrogen production in a two-stage process with dark anaerobic for 24 h and light irradiation with the addition the of 15μM CCCP (carbonylcyanide-m-ChlorophenyIhydrazone ) for hydrogen production .The highest hydrogen production was obtained for Platymonas Sucordiformis cells grown under white light ,while the lowest being under the blue light