CULTURE CONDITIONS AND THE DEVELOPMENT OF THE PHOTOSYNTHETIC MECHANISM

Abstract

C. pyrenoidosa was grown in a con- tinuous culture apparatus with light intensity provided by tungsten lamps the only variable in culture conditions. Light intensity curves were detd. as characteristic of the photosynthetic mechanism of harvested cells and were referred to cell volume as an index of cellular quantity. Cells grown at about <35 f.c. develop a capacity for a high rate of photosynthesis (cmm. O2/hour/cmm. cells). At light intensities above or below this range the cells produced have a lower capacity for photosynthesis. A similar effect is observed for rate of photosynthesis per unit dry wt. or unit N. Rate photosynthesis per cell or per unit chlorophyll shows no maximum but increases throughout the range of intensities studied (9-325 f.c). Maximum rate of growth is attained at about 100 f.c. The hypothesis is advanced that above this light intensity cells develop a mechanism which opposes the photosynthetic process and removes photosynthetic products. A low capacity for photosynthesis shown by cells grown at < 35 f.c. finds no explanation. The shape of the light intensity curve is markedly affected by the light intensity at which the cells have been cultured. Cells grown at lower intensities give light intensity curves approaching the Blackman type with short transition between light-limitation and light-saturation.