Long-term storage of collection cultures of actinobacteria

A total of 553 collection cultures of actinobacteria, including 453 reference ISP strains, were studied after long-term storage in a lyophilized state, as soil cultures, and under mineral oil. It was established that their viability reached a near-critical level. A number of methodological approaches to optimization of activation and proliferation of actinobacteria made it possible to restore the viability and major cultural and morphological properties of 65% of actinobacteria stored in a lyophilized state or under mineral oil. The actinobacteria stored as soil cultures almost completely lost their viability. Resuscitated actinobacteria exhibited a high level of genetic instability, which resulted in the emergence of more than three phenotypically different types of colonies. The population spectrum shifted towards an increase in the content of minor phenotypes with low spore-forming capacity. Significant changes in the cultural and morphological properties of a number of resuscitated strains were observed. Desirability of the application of antioxidants or growth-stimulating compounds in order to restore the viability of Actinobacteria cultures and to stabilize them after long-term storage was demonstrated.