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Effects of Cation Levels of the Nutrient Medium on the Biochemistry of Chlorella

I. Concentration Series ¹

^a Department of Botany, University of Maryland, College Park, Maryland 20742

The effects of variations in nutrient cation levels on the growth and biochemistry of Chlorella were investigated. This study involved concentration-series experiments in which the levels of Mg²⁺, K⁺, and Ca²⁺ varied from deficiency to toxicity levels for growth. The nutrient sufficiency concentrations of Mg²⁺ and K⁺ were 0.08 and 0.10 meq/1, respectively. Deficiencies of Mg²⁺ or K⁺ reduced the growth rate, as well as cellular total nitrogen and unsaturated fatty acid levels. K⁺ deficiency increased total lipid levels, while total fatty acids were unaffected. Increasing Mg²⁺ or K⁺ concentrations in the nutrient media were accompanied by corresponding increases in growth rate and certain biochemical fractions. Calcium was without effect except at a toxicity level. Cellular sufficiency concentrations for Mg²⁺ and K⁺ were 0.3 and 1.2% of the dry weight, respectively.