A modified perlite protocol with a mixed dimethyl sulfoxide and trehalose cryoprotectant improves the viability of frozen cultures of ectomycorrhizal basidiomycetes

Vermiculite as a culture substrate greatly improves the viability of frozen cultures of ectomycorrhizal basidiomycetes

We assessed a new cryopreservation protocol that uses vermiculite as a culture substrate, called the vermiculite protocol (VP), by assessing the viability, recovery time of hyphae after revival, and colony diameter of cryosensitive ectomycorrhizal basidiomycete strains after storage for 2 weeks or 1 year in a vapour-phase liquid nitrogen tank. Twelve difficult-to-preserve strains of nine species (Amanita citrina, A. pantherina, A. rubescens, A. spissa, Kobayasia nipponica, Lactarius akahatsu, L. hatsudake, Sarcodon aspratus, and Tricholoma flavovirens) that did not achieve good revival after cryopreservation with our previous Homolka's perlite protocol and modified perlite protocol (MPP) experiments were used to assess the new methodology. Vermiculite and liquid medium were put into a cryotube and inoculated with an agar plug containing mycelia. The cryotube was cultured for various incubation times. After adequate mycelial growth, a mixture of cryoprotectants (5% dimethyl sulfoxide and 10% trehalose [5D10T] or 5% glycerol and 10% trehalose [5G10T]) was placed into the cryotube. The cryotube was frozen in a freezing container in a -80 °C freezer and then stored in vapour-phase liquid nitrogen. In the recovery test, 10 of 12 strains showed 100% revival after 2 weeks of storage in the 5G10T cryoprotectant, and all 12 strains showed 100% revival after 2 weeks of storage in the 5D10T cryoprotectant. Furthermore, all strains were viable after 1 year of storage in a vapour-phase liquid nitrogen tank. Thus, the VP is applicable to a wide range of ectomycorrhizal basidiomycete cultures, including highly cryosensitive strains.

STABILITY OF THE STRAINS OF BASIDIOMYCETES DURING STORAGE IN THE COLLECTION

Basidial macromycetes may be a material for the development of new biotechnologies, medical preparations, components of dietary nutrition. Therefore, it is necessary for the highest level of quality for maintenance and identification of mushroom strains in the collection. An important parameter, in this case, is a stability of isolated and described collection strains of basidiomycetes. Stability is one of the key issues of long-term preservation of pure culture collections. For the collection of medicinal basidiomycetes of ONU I.I. Mechnikov, which preserves by the method of periodic reseeding of colonies the strain stability had not been studied yet. The goal of this research is to study the stability of this collection by a growth rate of mushroom colonies and electrophoretic spectra of carboxylesterases after different times of storage of cultures on malt agar. In this research the strains of three age categories (1, 2 and 3 years) of storage on malt-agar medium at temperature 4 ° С for were tested. The radial growth rate of their vegetative mycelium and the spectra of multiple molecular forms of carboxylesterases by the method of vertical electrophoresis in 7% of polyacrylamide gel were investigated. It was established that the stability of the radial growth rate of A. auricula-judae, F. velutipes, G. lucidum the vegetative mycelium after different storage periods is high according to the values of variation coefficients. At the same time, the expression of molecular forms of carboxylesterase showed sufficient variability. Partially conservative molecular forms were detected in some age groups of strains, as well as for individual strains. Thus the growth rate of colonies is a stable indicator and the molecular forms of carboxylesterases of different ages strains are variable.