"Special K", a new and improved trace element composition for Chlamydomonas medium

Janette Kropat, Davin Malasarn, Petr Ent and Sabeeha Merchant

Department of Chemistry & Biochemistry, UCLA, Box 951569, Los Angeles CA 90095, USA

Metals are utilized as cofactors in enzymes and thus are essential micronutrients for all organisms. Various culture media for Chlamydomonas are in use which have a broad variety in their molar composition of trace elements. Two of the most commonly used media provide the trace elements as a mixture originally designed by Hutner for use in bacteria. Due to a discarded precipitate during the preparation of the Hutner solution the exact metal composition is unknown. Using our knowledge of deficiencies in Chlamydomonas and ICP-MS measurements for determination of internal metal concentrations we have redefined the trace metal solution. Zinc, copper, manganese and molybdate are required in lower concentrations than provided via Hutner whereas borate and cobalt are not essential. On the other hand, selenium supplementation can be beneficial in certain growth situations. The new composition improves the growth of Chlamydomonas and individual stock solutions allow easy manipulation of trace elements. The inclusion of EDTA buffer ensures the solubility of each trace nutrient.

e-mail address of presenting author: kropat@chem.ucla.edu