Preparation of protoplasts from the cyanobacterium Spirulina platensis and a novel viability assay

A method is described for the isolation of protoplasts from the cyanobacterium Spirulina platensis using an elite strain (S.pl. FT 06) selected after screening. Trichomes of the cyanobacterium were treated with lysozyme (0.1%) for 28 h at room temperature in 0.03 mol l-1 phosphate buffer (pH 6.8) with 0.5 mol l-1 mannitol as the osmoticum. This resulted in an 80% yield of protoplasts. Cells were intact in their fine structure and viable as evidenced by a rapid and efficient viability assay using a novel mixture of fluorescein diacetate and calcofluor white.