Identification and Characterization of Gliocladium viride Isolated from Mushroom Fly Infested Oak Log Beds Used for Shiitake Cultivation

ABSTRACT

A green mold species that has not previously been reported in Korea was isolated from oak log beds used for shiitake (Lentinula edodes) cultivation that were infested by mushroom flies. In this study, we identify the mold species as Gliocladium viride (an anamorph of Hypocrea lutea) and describe its mycological properties. The fungus was cottony on both potato dextrose agar (PDA) and Czapek yeast extract agar (CYA), but was colored white on PDA and became yellowish green and brown on CYA. Mycelial growth on PDA attained a diameter of 73 mm at 30degrees C after 5 days. The fungus grew faster on malt extract agar (> 80 mm, 5 days at 25degrees C) compared to CYA and PDA (< 68 mm, 5 days at 25degrees C). Penicillate conidiophores of the fungus are hyaline, smooth walled, branching above typically in four stages, and 120~240 microm in length. Club-shaped or slender phialides are formed on the metulae. Conidia of the fungus were ovate and elliptic, yellowish brown and green, and 2.5~3.0 microm x 1.8~2.3 microm in size. Typically, slimy conidia are formed in a mass and colored brown to dark green to almost black. The internal transcribed spacer rDNA and translation elongation factor 1 alpha gene sequences of the fungus isolated here show 99% identity with previously identified G. viride strains.