Evaluation of Algal Culture Viability and Physiological State by Fluorescent Microscopic Methods

The viability of algae belonging to divisions Cyanophyta, Chlorophyta and Xantophyta has been assessed by chlorophyll autofluorescence and after staining with fluorescent dyes rodamin B, neutral rot, calcofluor white and fluorescein diacetate. For this purpose the fluorescence of algal cells from fresh and old cultures was scored. It was established that chlorophyll autofluorescence could be recommended as the most convenient method for differentiating living and dead algal cells. Since in most of the algal species investigated chlorophyll autofluorescence masked cytoplasmic fluorescence, the tests based on fluorescence of the living cytoplasm (as in the case of the fluorochromatic test and CFA) proved to be inappropriate. These viability tests which are based on the fluorescence of the dead cell cytoplasm (NR and RB) appeared to be useful for vitality assessment, because chlorophyll fluorescence was lost and did not mask cytoplasmic fluorescence. The conclusion is drawn that in this kind of investigation an individual approach should be applied for each systematic section of algae.