Long-term maintenance of 23 strains of freshwater microalgae on solid microbiological culture media: A preliminary study

Abstract

In this work, the ability of 23 strains of freshwater microalgae to be maintained on 10 different solid culture media was evaluated. Depending on the type of media, it was found that all strains of microalgae could be recovered after 19–24 months of culture in the dark. Bold's basal medium (BBM), BBM + 5% (v/v) coconut milk (CMA) and BBM + 5% (w/v) powdered skim milk (SMA) solidified with 1.5% (w/v) agar were good choices for growth and maintenance of freshwater microalgae strains in this study. Out of 23 strains of microalgae, 21 samples maintained on BBM, 21 from CMA and 12 from SMA were viable and successfully recovered on solid BBM. Strains which were maintained on nutrient agar (NA), luria-bertani agar (LB), potato dextrose agar (PDA) and trypticase soy agar (TSA) required pre-culture on solid BBM or CMA supplemented with glucose, sucrose or both, prior to final recovery on plain BBM. Four samples from NA, 2 from LB, 2 from PDA and 1 from TSA were successfully recovered. Findings from this study suggests that long-term maintenance of freshwater microalgae on solid media in the dark could be used as a possible alternative to cryopreservation.