Maximizing Photosynthetic Productivity and Light Utilization in Microalgae by Minimizing the Light-Harvesting Chlorophyll Antenna Size of the Photosystems

MELIS, ANASTASIOS; NEIDHARDT, JOHN; BAROLI, IRENE; BENEMANN, JOHN R

BioHydrogen

Plenum

Lugar: New York; Año: 1998; p. 41 - 52

The photosynthetic characteristics of the green alga Dunaliella salina were analyzed in growth under low or high irradiance and in the presence of NaHCO3 or supplemental CO2 as the inorganic carbon source. High-light NaHCO3-grown cells exhibited signs of chronic photoinhibition, characterized by a lower pigment content, a highly truncated chlorophyll antenna size for the photosystems, and accumulation of photodamaged photo-system-II reaction centers in the chloroplast thylakoids. In spite of these deficiencies, high-light NaHCO3-grown cells showed photosynthetic productivity on a per chlorophyll basis (300 mmol O2 mol-1 Chl s-1) that was ~ 3 times greater than that in the normally pigmented LL-grown cells (~ 100 mmol O2 mol-1 Chl s-1). Repair of photodamaged centers in the high-light NaHCO3-grown cells, occurring in the absence of a light-harvesting chlorophyll antenna size enlargement, increased photosynthetic productivity further to ~ 650 mmol O2 mol-1 Chl s-1 in these cells. From the analysis of the results, it was inferred that Dunaliella salina with a highly truncated chlorophyll antenna size, when grown under supplemental CO2 rather than NaHCO3, will display light-saturated rates of photosynthesis approaching 2000 mmol O2 mol-1 Chl s-1. Microalgae with such superior photosynthetic productivity and light utilization efficiency are ideal for commercial applications in CO2 mitigation, and novel biochemical, biomass, or hydrogen production.