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The Influence of Carbon Dioxide and Oxygen Partial Pressures on Chlorella Growth in Photosynthetic Steady-state Cultures
Abstract
The effects of O2 and CO2 partial pressures in the range 0 to 1 atm on the maximum growth rate, starch production and photosynthetic efficiencies of growing cultures of Chlorella were determined. Stepwise increases of about 0.2 atm in the partial pressure of either gas inhibited growth, often completely. In contrast, gradual increases (steps of less than 0.1 atm) in the partial pressure of either gas maintained growth, and the cultures became adapted to high partial pressures. Adapted cultures tolerated 0.6 atm CO2 or 0.8 atm O2 without any growth inhibition as measured by maximum specific growth rate. Also, starch production was little affected by the increases in O2 or CO2 partial pressures.
The photosynthetic efficiency, as measured by the growth yield from light (400 to 700 nm wavelength) absorbed, and the maintenance energy were the same in adapted cultures with the O2 partial pressure at either 0.2 or 0.8 atm. The maximum growth yield from light was 0.0172 g kJ−1, with 95 % confidence limits of 0.0156 to 0.0189. The maintenance energy was 1.27 kJ (g dry wt)−1 h−1, with 95 % confidence limits of 0.89 to 1.65. The photosynthetic efficiency in light-limited cultures was 36.5 %, with 95 % confidence limits of 33 to 40 %.
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© Society for General Microbiology 1980