1MAXIMIZING PHOTOSYNTHETIC EFFICIENCIES AND HYDROGEN PRODUCTION BY MICROALGAL CULTURES

For algal mass cultures and H2 production, conditions that maximize photosynthetic productivity and solar conversion efficiency are important in determining sustainability and profit. We have shown [Melis et al. (1999) Journal of Applied Phycology 10: 515-525] that photosynthetic efficiencies and hydrogen production by microalgal cultures can be increased upon minimizing the number of the light-harvesting chlorophyll (Chl) antenna pigments of photosynthesis. A highly truncated light-harvesting Chl antenna size in green algae could result in: (a) 6-7 times greater photosynthetic productivity (on a per Chl basis), compared to that of normally pigmented cells, and (b) ~3 times greater yields of photosynthesis and H2 productio under mass culture, compared to that of normally pigmented cells. We report here the application of molecular genetic approaches for the generation of transformant green algae with a permanently truncated Chl antenna size. Upon generating and screening a library of 6,500 DNA insertional transformants in the green alga Chlamydomonas reinhardtii, 155 mutants aberrant in Chl fluorescence, i.e., possibly aberrant in Chl antenna size, have been isolated. Three distinct classes of mutants were identified: mutants aberrant in Chl