Effect of Temperature and Light Intensity upon the Growth of Chlorella in High Population Density

Abstract

Effects of light intensity and temperature upon the growth rate of Chlorella in cultures of high population density was investigated. It was shown that, by and large, the following equation fits in with the experimental data obtained in the temperature between 7°and 25°C and the range of light intensity between 0.80 and 50.0kilolux. ΔV/Δt=5.3×k/εD log(1+αI/k) where V is the packed cell volume (in ml) per liter of culture, t time of culture (in days), k the maximum growth rate (ΔlogV/Δt in 1/day) at each temperature, α a temperature-independent constant (in terms of 1/day-kilolux), εthe extinction coefficient of the algal suspension (in terms of 1/cm-ml), and I the light intensity (in kilolux). The only disagreement between calculated and observed values was found in the cultures of low temperature (7°C) kept under strong illumination (25-50 kilolux), in which case the cells gradually bleached and eventually ceased to grow for some unknown physiological reasons.