Hydrurus foetidus (Chromista,Chrysophyceae): A large freshwater chromophyte alga in laboratory culture

The psychrophilic freshwater alga Hydrurus foetidus (Villars) Trevisan has previously resisted laboratory culturing in liquid media. We investigated the use of microbiological techniques adapted to specific requirement for low temperature and high turbulence of the alga. We found that successful culturing required cleaning steps, where pieces of the alga were dissected out and plated on agar under cold conditions. From here, unialgal colonies could be isolated and inoculated into liquid media under appropriate conditions. Turbulence, created by a laboratory shaker, is critical. Sufficient light (30–100 µmol m^–2 s^–1) and low temperature (here 2–3°C) are necessary. This rather common but highly under‐investigated freshwater alga has potential for basic and applied research when available as laboratory cultures.