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Five different anaerobic fungi (Neocallimastix frontalis N1-1, Piromyces communis P1-2, Orpinomyces spp. 02-2, Caecomyces communis CI-5, Anaeromyces spp. AI-3) isolated from the rumen of a male Holstein were compared in fermentation characteristics and enzyme activities in a hope to select a proper fungal species with a high fiber-degrading capacity. The fungal isolates were incubated in Lowe´s medium containing rice straw as a substrate for 5 days, and pH, gas production, volatile fatty acid concentration, and activities of carboxymethylcellulase(CMCase), xylanase and amylase in the culture supernatant were determined. Culture supernatant of N-1 had the lowest pH, and monocentric generally showed lower pH than polycentric fungi. N-1 and P-I produced more gas than the other fungal isolates. Overall gas production data indicated that it could be used as a potential indicator of fungal growth. The concentration of acetic acid in the culture fluid of N1-1 and A1-3 was significantly higher than that of the other fungal isolates, and isobutylate was detected only in the culture of 02-2. All of five fungal species produced CMCase, xylanase and amylase, and Nl-I showed the highest enzmye activity. Based on data obtained in this study, Neocallimastix frontalis showed the highest fiber digesting ability among 5 fungal species.
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