Influence of Growth Status and Nutrients on Extracellular Polysaccharide Synthesis by the Soil Algachlamydomonas Mexicana(chlorophyceae)¹

Increased levels of nitrogen in liquid growth medium bring about increased growth and a delay in extracellular polysaccharide production by Chlamydomonas mexicana Lewin on a per‐cell basis. Addition of nitrogen to stationary phase cultures causes renewed growth and a temporary lag in polysaccharide synthesis until growth again ceases. Removal of nitrogen terminates growth, causing an immediate increase in polysaccharide synthesis. Phosphate‐starved cells show a response similar to nitrogen‐starved cells, indicating that the beginning of stationary phase and not nitrogen depletion causes the stimulation in extracellular polysaccharide synthesis. As similar results are assumed to occur on soil, the significance of this response is discussed.