Effects of cation levels of the nutrient medium on the biochemistry of chlorella: I. Concentration series.

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 Mg(2+), K(+), and Ca(2+) varied from deficiency to toxicity levels for growth. The nutrient sufficiency concentrations of Mg(2+) and K(+) were 0.08 and 0.10 meq/1, respectively. Deficiencies of Mg(2+) 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 Mg(2+) 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 Mg(2+) and K(+) were 0.3 and 1.2% of the dry weight, respectively.