The production of clonal and axenic cultures of microalgae using fluorescence-activated cell sorting

Unialgal cultures of the flagellate algae Cyanophora paradoxa, Haematococcus lacustris, Monomastix sp., Scherffelia dubia and Spermatozopsis similis which contained bacteria were sorted by flow cytometry to obtain axenic clonal cultures. The variables used for fluorescence-activated cell sorting (FACS) were chlorophyll autofluorescence, forward scatter and side scatter of the laser beam. To produce clonal cultures, a single cell was sorted into each culture flask. Depending on the species, about 20–30% of the sorted cultures grew successfully and at least 20% of these were axenic even if the numerical ratio betweeen bacteria and algae in the original cultures was as high as 300:1. FACS represents an effective and rapid method for the preparation of clonal and axenic cultures of microalgae.