Implementación de la gelificación iónica con biopolímeros y el método de Castellani como dos métodos accesibles para la preservación del hongo micorrízico Ceratobasidium sp

Abstract

Orchid mycorrhizal fungi are essential for the germination of their seeds and the maintenance of populations in their natural habitat. Preserving mycorrhizal fungi in a controlled laboratory environment can ensure the morphological and genetic integrity of a culture, whose purpose is to maintain the germinative characteristics of the original strain. Currently, the Orchidarium of the University of Cuenca preserves a species of mycorrhizal fungi: Ceratobasidium sp., through subcultures in Potato Dextrose Agar (PDA) and Oatmeal Agar (OMA). However, in the long term, there is a risk of contamination with other microorganisms and altering its physiological and genetic characteristics. In this study, two accessible methods for the long-term preservation of Ceratobasidium sp. were investigated: ionic gelation and the Castellani method. In ionic gelation, fungal mycelium was encapsulated within sodium alginate and carboxymethylcellulose (CMC) beads. In the Castellani method, plugs of PDA agar (traditional method) and filter paper disks (modified method), both colonized by mycelium, were submerged in sterile distilled water inside cryovials. Concentrations of 1%, 1,5% and 2% sodium alginate and 1 % and 1,2 % CMC were shown to produce beads with favorable characteristics for long-term storage at 4°C. Additionally, the Castellani method is effective in preserving the Ceratobasidium sp. mycelium.