Degradation of maize stem by two rumen fungal species, Piromyces communis and Caecomyces communis, in pure cultures or in association with cellulolytic bacteria.

Abstract

Two species of rumen fungi, Piromyces (Piromonas) communis FL and Caecomyces (Sphaeromonas) communis FG10, were cultured alone or in association with the cellulolytic bacteria Ruminococcus flavefaciens or Fibrobacter succinogenes on maize stem. A kinetic study of the degradation of the substrate was then made. After 48 h of culture, all non-lignified tissues observed by scanning electron microscopy disappeared with P communis and degradation was as complete as that observed in the rumen. In contrast, C communis degraded little of the plant cell walls. The ability of P communis to more rapidly degrade maize stem was probably due to the presence of filamentous rhizoids. The extent of dry matter loss after 8 days of incubation was practically the same in all the monocultures and in the 4 cocultures. However, the rate of degradation was faster in the bacterial than in the fungal monocultures and the co-cultures. No metabolic interaction was observed.