Abstract

Effects of silicon, calcium or boron on cell growth and lipid accumulation in diatoms were studied. Growth of Chaetoceros gracilis showed a log phase and a stable phase under silicon-rich condition. Cells produced more pectin in log phase while accumulated more lipids and chrysolaminaran in stable phase when cultured in silicon-rich solution. Silicon deficient treatment reduced pectin production and cell growth, increased lipid contents, but reduced total lipid production compared to silicon-rich condition. Silicon depletion by the end of log phase did not affect pectin production and cell growth but increased lipid production and reduced chrysolaminaran accumulation. No differences were found between calcium and boron treatments, both increased pectin production, cell growth, total lipid production and chrysolaminaran accumulation compared to silicon-deficient treatment but they were not as effective as silicon-rich treatment. Results showed that diatoms could be used as a model system in studying lipid biosynthesis and its regulation.