Production of carbohydrates by the marine diatom Chaetoceros affinis var. willei (Gran) Hustedt. I. Effect of the concentration of nutrients in the culture medium

The chemical composition of cells of Chaetoceros affinis var. willei (Gran) Hustedt grown in batch culture was markedly influenced by the concentration of nutrients in the medium. In the logarithmic growth phase the content of cellular glucan was relatively low, but in the stationary phase the glucan content showed a rapid increase which seemed to coincide with the depletion of nitrate from the medium. This led to very pronounced variations in the ratio of protein to carbohydrate. This ratio can easily be determined and seems to be a sensitive and convenient parameter for characterizing the physiological state of the diatom cells. In the stationary phase the alga also produced considerable amounts of an extracellular polysaccharide, particularly when grown in a medium with a high proportion of nitrate to phosphate.