초록
<P><B>Abstract</B></P> <P> <I>Chlamydomonas reinhardtii</I> cc124 and <I>Azotobacter chroococcum</I> bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H<SUB>2</SUB> yield. The results demonstrated that the optimal culture conditions for the highest H<SUB>2</SUB> production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m<SUP>−2</SUP> s<SUP>−1</SUP>. Under these conditions, the maximal H<SUB>2</SUB> yield was 255 μmol mg<SUP>−1</SUP> Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H<SUB>2</SUB> yield included decreased O<SUB>2</SUB> content, enhanced algal growth, and increased H<SUB>2</SUB>ase activity and starch content of the combined system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Reducing the O<SUB>2</SUB> content in the culture of <I>C. reinhardtii</I> is essential for its hydrogen production. </LI> <LI> Co-cultivation of <I>A. chroococcum</I> and <I>C. reinhardtii</I> improved hydrogen yield of <I>C. reinhardtii.</I> </LI> <LI> <I>A. chroococcum</I> promoted growth and starch content of the <I>C. reinhardtii.</I> </LI> <LI> <I>A. chroococcum</I> decreased the respiratory rate and dissolved O<SUB>2</SUB> of the <I>C. reinhardtii.</I> </LI> <LI> <I>A. chroococcum</I> promoted activity of hydrogenase of the <I>C. reinhardtii</I> in co-culture medium. </LI> </UL> </P>