A simple technique for washing microalgae in preparation for laboratory culture experiments, with particular reference toMicrocystis aeruginosaKutz. emend. Elenkin

Abstract

A simple method was developed which allows the colonial blue-green alga, Microcystis aeruginosa Kütz. emend. Elenkin, to be washed in order to minimize extracellular nutrient carry-over to a new growth medium. The technique involves the filtration of an algal suspension on to a cellulose ester or polycarbonate membrane filter (pore size 0·22–3·0 µm) to allow in situ washing. The filter is transferred to a small beaker and the alga is resuspended into the desired medium using a magnetic stirring bar. This technique did not affect the growth rate or the mean colony volume of an exponentially growing culture of Microcystis filtered on to a 0·45 µm pore size cellulose ester membrane filter. Stagnant cultures of Microcystis were found to have significantly larger mean colony volumes than swirled cultures.