Stability and Qualification of a Legacy Fungal Collection.

Microbial culture collections are valuable repositories for qualified and diverse microorganisms, playing a pivotal role in research, education, innovation, as well as in our response to current and emerging public health and societal challenges. However, such precious holdings, when not integrated in professional biobank infrastructures, may be vulnerable to major risks such as staff retirement, changes in the institutional strategy, or natural disasters. The process of preserving and rescuing "historical" collections can be long and treacherous with a loss of a part of the collection. At the Biological Resource Center of Institut Pasteur, we undertook the challenge of rescuing the dormant legacy fungal collection. A total of 64 freeze-dried strains, including yeasts and filamentous fungi, were characterized by using a polyphasic approach combining morphological features and molecular data. We assessed the viability, purity, and authenticity of selected strains isolated from multiple sources and stored for more than 20 years. Our preliminary results show long-term stability of the selected strains and successful qualification in terms of purity and authentication. Moreover, based on the most recent taxonomic revisions, we updated and revised the nomenclature, where applicable. Our findings demonstrated the potential value of reviving historical microbial collections for biobanking and research activities and reassure us about the collection's future reopening.