Range and Optimum Growth Concentrations of Phosphate and Nitrate for Chlamydomonas reinhardtii

A study was conducted on the alga Chlamydomonas reinhardtii to determine the range and optimum growth concentrations of phosphate and nitrate. There are only a few species of algae for which this type of data is known. Inorganic nutritional data is basic to the understanding of the complexities of phytoplankton ecology and eutrophication. The "plus" strain of this heterothallic alga was cultured in a TRIS-buffered inorganic medium with various concentrations of sodium phosphate and potassium nitrate and adjusted to a pH of 7.4. The axenic cultures were evaluated at the end of 6 days with a spectrophotometer, at a wavelength of 645 millimicrons. An environmental chamber adjusted to 12 hours day/night length and illumination of 1,400 footcandles at 22°C was employed in the study. The phosphate range of growth was 0.07 to 3,200 ppm PO4 with optimum growth from 3 to 950 ppm PO4. The nitrate range of growth was 2 to 9,700 ppm NO3 with optimum growth from 33 to 5,000 ppm NO3. These data confirm earlier work which indicated that this organism is very tolerant of organic pollution. This alga has high nutrient requirements for survival and optimum growth compared to other algae.