EFFECT OF LIGHT INTENSITY AND GLYCEROL ON THE GROWTH, PIGMENT COMPOSITION, AND ULTRASTRUCTURE OF CHROOMONAS SP.1,2,3

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Abstract
SUMMARY: Growth of Chroomonas sp. increased with light intensity (100, 1800, and 2700 μW/cm2) with a fivefold increase from the lowest to the highest intensity. Chlorophyll and phycocyanin content per cell were greater in cells grown at low light intensity, but the ratio of chlorophyll a and c did not vary appreciably. Cells grown at low light intensity had 30% more phycocyanin than cells grown at high intensities of light. The chloroplast of cells with the higher phycocyanin content had average intrathyla‐koidal widths of 300 Å, whereas those cells with the lower phycocyanin content had average intrathylakoidal widths of 200 Å. This result is compatible with the hypothesis that phycocyanin is located in the intrathylakoidal space in the cryptophyte algae. Of the various energy sources tested, only glycerol was able to support limited growth tinder nonphotosynthetic conditions. Under no condition was the chloroplast reduced to an elioplast or proplastid state. Starch accumulation was greatest in cells grown in continuous while light in glycerol. Eye‐spots were commonest in cells grown in darkness and interrupted every 24 hr by a few seconds of white light. It was concluded that this organism is an obligate phototroph.