KWRRI Research Reports


The chemical composition of algae grown in batch culture depends mainly on environmental conditions, nutrient availability, presence of predators, cell age, and species. The effects of nutrient availability and cell age on the composition of three unialgal cultures (algae + bacteria) and one hetergeneous culture (algae + bacteria + microscopic animals) were evaluated. The cultures were grown in batch culture under both nutrient-abundant and nutrient deficient conditions and the changes in compositions were observed. Luxurious uptake where nutrients are incorporated into cellular protoplasm at levels greater than those necessary for growth, and super-luxurious uptake, where some nutrients are stored rather than converted into algal protoplasm, were observed. The commonly used model for calculating the weight percentage of protein was inaccurate when super-luxurious uptake occurred. Composition of the cultures was generally characterized by protein synthesis during the nutrient-abundant growth phase, by a fluctuating composition during transition from nutrient-abundant to nutrient-deficient growth, and by lipid and/or carbohydrate synthesis and the establishment of a relatively constant composition during the nutrient-deficient growth phase. Two unialgal cultures accumulated carbohydrates and one accumulated lipids. Soluble extracellular substances were produced in all cultures which caused high concentrations of color.

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The work upon which this report is based was supported by funds provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Research Act of 1964.