The development of new methods for long-term maintenance of algal and cyanobacterial cultures
The research was focused on the development and standardization of modern cryopreservation techniques for long-term maintenance of scientifically and biotechnologically important strains of algae to ensure their genetic stability. More than 300 strains of soil algae and cyanobacteria, representatives of main taxonomical and morphological groups, and isolated from different climatic regions have been tested in the Institute of Soil Biology ASCR using different cryopreservation protocols. Mechanisms of cryoinjury (critical damage) of cryopreservation recalcitrant or problematic species (strains) were studied using differencial scanning calorimetry, cryomicroscopy, FluorCam, TEM and GC techniques. The elucidation of some mechanisms resulted in the development of new cryopreservation methods and protocols enabling successful cryopreservation of some cryopreservation recalcitrant strains. Novel encapsulation-dehydration method using different osmotica was found to be very promising for maintenance of problematic strains. Results from the study of the effect of cold acclimation on survival of low (to -40 °C) and ultra-low (to -196 °C) temperatures showed species and strain specific response of algae and could be easily applied in practice. Suitability of different methods for measuring of post-cryopreservation viability and recovery has been tested on most of studied strains. Two novel, non-destructive method were developed, the first one based on digital imaging (Naja Image Analysis) of algal re-growth, the second based on analysing photosynthetic activity and reversibility of photosynthetic apparatus damage using fluorescence kinetic camera (different protocols and parameters were tested and optimized). The results were presented at 9 international conferences.