Applicability of liquid-drying for the preservation of microalgal cultures

Abstract

Suitability of liquid drying (L-drying) for preserving nine algal strains was tested using fresh culture medium and 12% saccharose as suspending medium. Accelerated shelf life study lasting one and two weeks at 37°C was done on L-dried microalgae in ampules to simulate 25 years of prescribed storage at refrigeration temperature. Viability of microalgae was determined by cell counts and by the most probable number (MPN) technique in broth. L-drying was found to be suitable for preserving Anabaena laxa BIOTECH 4003, A. variabilis BIOTECH 4004, Aphanothece pallida BIOTECH 4005, and Gloeotrichia natans BIOTECH 4007 with either fresh culture medium or 12% saccharose as suspending medium. Sufficiently high numbers of >1100 MPN/ampule was attained after accelerated shelf life treatment. Different strains of Hapalosiphon welwitschii displayed varied reactions to L-drying. H. welwitschii BIOTECH 4008 survived the L-drying process, however, it maintained numbers of >1100 MPN/ampule only after 1 week of accelerated shelf life treatment. H. welwitschii BIOTECH 4017 did not survive in appreciable numbers fit for this preservation technique. Fischerella ambigua BIOTECH 4006 Spirulina platensis BIOTECH 4012 and Chlorella sorokiniana BIOTECH 4016 failed to revive after L-drying. Results indicate that not all blue-green algae can be preserved by L-drying and strains within a species may exhibit different reactions to the process. Fitness of preservation by L-drying should be explored with every new isolate of cyanobacteria.