Growth and lipid class composition of the marine diatom, Chaetoceros gracilis, in laboratory and mass culture turbidostats

Publisher Website
Google Scholar
Abstract
Traditionally, laboratory study of phytoplankton ecology and physiology has been performed in batch cultures. Such cultures are also commonly used when phytoplankton are needed as a food supply for herbivores in an experimental or aquaculture setting. The great advantage of batch culture is its simplicity; however, in studies requiring well-defined growth conditions or in situations where yield is important, then technically more complicated culturing devices may offer advantages. We compare here growth of the unicellular marine diatom Chaetoceros gracilis in batch culture, simple cage culture and cage culture turbidostat. We also examined growth and lipid composition in cultures of two different scales: 250 ml and 200 1. Cage culture turbidostats produced a higher daily yield than could be achieved by either batch culture or simple cage culture, as well as permitting closer control over environmental variables. One variable that clearly affected lipid yield was nitrogen supply rate. The highest triglyceride yields were obtained at the lowest rates of nitrogen supply. Low light levels had a similar effect on cell lipids. Illumination may have limited population growth rate in the 200 1 cage culture turbidostats under our culture conditions; the physiologically limiting growth rate was not reached in this series of experiments. This method of mass culturing shows promise for applications in laboratory experiments or aquaculture because of its ability to produce diatoms in a chosen phase of growth.