Cultivation Optimization Of A Marine Green Alga, Platymonas Subcordiformis For Hydrogen Production

The optimization of the key nutrition and culture condition for amarine green alga, Platymonas subcordiformis which is able to evolveH2 photosynthetically, were studied in this thesis. Effect of differentculture factors and different growth phases on photo-biologicalhydrogen production of P. subcordiformis were characterized, and avariety of cell material were reviewed, then some basic requirementsof hydrogen production on the culture of P. subcordiformis weregained.P. subcordiformis grows very slowly in artificial and naturalseawater medium in the flask. The growth dynamics curve of P.subcordiformis in basic medium is got, which proves P.subcordiformis is easily cultured. Through optimizing the content ofFeCl₃, NaHCO₃, NaH₂PO₄ and NH4Cl in seawater with the method oforthogonal tests and the content of light intensity, initial pH andinoculation density, a higher biomass productivity of 450 ×10⁴cells ·ml^-1 and a maximum growth velocity of 71.5 ×10⁴cells·ml-1day^-1 was obtained after 11 days in a flask.P. subcordiformis is able to generate H2 photo-synthetically withCCCP (Carbonyl cyanide m-chlorophenylhydrazone) when exposed tolight after a period of anaerobic, dark incubation. At the end ofexponential phase, the ability of production reached the maximum. Ata higher light intensity, the alga grew faster, the chlorophyllconcentration was lower, and gave a highest H2 productivity. Theresults indicated that improving of light intensity, optimizing ofculture conditions may obtain more biomass, and can increase H2production yield of P. subcordiformis. Biocoil airlift photobioreactor for P. subcordiformis culture wasstudied. The results indicated that low-high hydrodynamic stress onalgae and poor mixing in helical tube restrained badly growth of algacells. So the result of A/V is high in thin tubular photobioreactor,however successful culture of P. subcordiformis in this type ofphotobioreactor is difficult.