Effect of coumarin on growth and metabolism of Pythium.

Coumarin concentrations that inhibited growth of Pythium sp. rapidly decreased the rate of incorporation of [14C]glucose into the mycelium. Coumarin also reduced drastically the carbohydrate and protein content of the cytoplasm and, to a lesser extent, the amino acid content and cell wall fraction. Enzymes related to the metabolism of cell wall polysaccharides were not affected during early exposure to the inhibitor. The possible mechanism of coumarin action via inhibition of glucose uptake is discussed in the light of the present findings.