Agaricostilbales » Kondoaceae » Mastigobasidium

Mastigobasidium intermedium

Mastigobasidium intermedium Golubev 1999, in Golubev, International Journal of Systematic and Evolutionary Microbiology, 49(3), 1301-1305 (1999).

Diagnosis: Growth in glucose-yeast extract-peptone water: after 3 d, the cells are oval or elongate [the width/length ratios are from 1.6-3-4 (mean 2-4)], 2-5-51 x 5.1-17-0 µm (mean 4.0 x 8.5 µm) and after a month, there is a sediment and a pellicle. Growth on yeast morphology agar (Difco): after a month, the streak culture is yellowish grey, smooth to delicately wrinkled, dull, soft, and has an entire or undulating margin; ballistospores are kidney-shaped, 2-5-5.1 x 5.9-10-2 µm (mean 4.0 x 7.6 µm), their width/length ratios are 1.3-2-5 (mean 1.9). Slide cultures on corn meal agar: after 10 d, a primitive pseudomycelium and poor true mycelium without clamp connections are formed. The species is heterothallic. Conjugation of opposite mating types on corn meal agar results within 2 weeks in the formation of true mycelium with clamp connections at the septa and thick-walled, intercalary and terminal, usually spherical, ovoid or sometimes pear-shaped teliospores, 11.4- 15-6 x 114-21.3 µm (mean 13.8 x 15.0 µm). After soaking 3- to 4-week-old teliospores for 8-10 months at 5 "C in distilled water they germinate by producing several (up to 10) narrow (width 14-23 µm) and long (from several tens to 200 pm) aseptate hyphae. Two- to four-celled club-shaped, usually curved phragmometa basidia (Figs 1 and 2), which may break up into individual cells (Fig. 2c), are born on the apex of these hyphae. One to eight ellipsoidal or bacilliform basidiospores, 2-5-4-2 x 5-1-9-3 pm (mean 3.5 x 7.0 µm), are formed terminally and laterally (Fig. 2). They occur singly or in clusters of up to six in number on pegs (Fig.2a) and germinate by budding (Fig. 2d). Fermentation: absent. Assimilation of carbon compounds: positive for D-glucose, arbutin, D-glucitol, D-mannitol, D-glucono-&lactone, 2-keto-~-ghconate, 5-keto-D-gluconate, succinate and ethanol; weak for D-galactose, sucrose, DL-lactate and citrate; weak or negative for L-sorbose and maltose; negative for D-glucosamine, D-ribose, D-xylose, L-arabinose, D-arabinose, L-rhamnose, methyl a-D-glucoside, salicin, melibiose, lactose, raffinose, melezitose, inulin, soluble starch, erythritol, ribitol, xylitol, L-arabitol, galactitol, i-inosito1 and methanol ; slow for trehalose, cellobiose, glycerol, D-glucuronate and D-galacturonate. Assimilation of nitrogen compounds: negative for nitrate, nitrite, creatine and creatinine; weak for L-lysine and cadaverine; positive for ethylamine. Maximum temperature of growth (on malt agar): 24 oC. Growth in vitamin-free medium: weak (thiamin is required for growth). Growth on 50 % (w/w) glucose-yeast extract agar: negative. Growth in the presence of 0.1 % cycloheximide: negative. Production of starch-like compounds: negative. Acid formation on chalk agar: negative. Urease activity: positive. Diazonium blue B reaction: positive. Sensitivity to mycocins: M . intermedium strains are weakly sensitive to the mycocins produced by Sporidiobolus salmonicolor, Rhodotorula glutinis and some killers of Rhodotorula mucilaginosa but are resistant to Sporidiobolus pararoseus and Rhodotorula pallida mycocins. They are insensitive to mycocins of tremellaceous (Bullera, Cystofilobasidium, Filobasidium, Cryptococcus) and ustilaginaceous (Tilletiopsis) yeast-like fungi (Golubev & Boekhout, 1995; W. I. Golubev, unpublished data). Cell wall structure by TEM: sections showed the cell wall to be of the basidiomycetous type. Monosaccharide composition of extracellular polysaccharides: mannose, glucose and galactose (at molar ratios of 1: 0.4: 0.3); fucose occurs in trace amounts. G+C content: 57-8, 60-0, 60.3 and 62.5 mol% (from Tm) and 58-9 mol% (by HPLC) (Nakase & Suzuki, 1986, 1987; Boekhout, 1991; Takashima et al., 1995a). The levels of DNA similarities of Mastigobasidium intermedium to species of Bensingtonia are 7-14Y0 (Takashima et al., 1995b). Major ubiquinone: Q-9 (minor fractions Q-8, Q- 10) (Nakase & Suzuki, 1987).

Index Fungorum Number: IF460068

Figure 1. Mastigobasidium intermedium VKM Y-2720T x VKM Y-2727AL grown on corn meal agar at 20 oC for 4 weeks and then incubated in water at 5°C for 40 weeks. Phase-contrast. Bar, 20 µm. (a)-(d) Young metabasidia on hyphal tips.