STUDIES OF MARINE PLANKTONIC DIATOMS:II. USE OF CYCLOTELLA NANA HUSTEDT FOR ASSAYS OF VITAMIN B12 IN SEA WATER

Abstract

Cyclotella nana Hustedt, a small centric diatom requiring vitamin B₁₂, was tested as a potential assay organism for that vitamin. Dose–response curves, measured by optical density and cell count, showed a linear relation between growth and B₁₂ concentration between 0 and at least 2 μμg/ml of the vitamin. Since the diatom is hardy, grows rapidly under a variety of conditions, and may be preserved for later examination, it represents a useful assay organism for certain applications such as oceanographic exploration.