Effect of nutrients and light intensity on growth of Mallomonas caudata (Synurophyceae)

We used batch cultures of three strains of the unicellular synurophyte Mallomonas caudata to investigate the effects of nitrate, phosphate, silicate and light intensity on population growth and growth rate. The three strains were isolated from three different reservoirs in Kyungpook Province, Korea. For all three strains, we observed high population growth under all nutrient concentrations studied, except at nitrate concentration below 0.8 mu M. The maximum growth rate (mu(max)) occurred at 8.2 mu M or 16.5 mu M nitrate, depending on the strain, and at 11.5 mu M phosphate. Silicate concentration had no effect on growth rate. With respect to light intensity, the maximum population growth and maximum growth rates (mu(max)) occured between 42 and 104 mu mol m-2 s-1 depending on strain and culture temperature. Population growth of these three strains under batch culture occurred over a wide range of nutrient and light intensities, but there seemed to be strain-specific differences that may represent adaptations to local environments.