Inhibition of cellulolysis by anaerobic rumen fungi using Butyrivibrio fibrisolvens WV1

Aims:To explore anaerobic fungal inhibition by rumen bacteria, Butyribivrio fibrisolvens WV1 and four fungal strains, namely Neocallimastix frontalis PNK2, Piromyces communis 12A, Piromyces sp.P1 and the polycentric fungus KP1 were used in this study. Methodology and results:The WV1 culture fluid was inoculated onto the fungal cultures and incubated.The degradation of dry matter in the paper strip within the medium, hydrogen production, and the pH of the culture fluid were assessed.To elucidate the characteristics of the inhibitory activity, the WV1 culture grown in glucose medium was subjected to centrifugation, followed by separate analyses of the supernatant and the cell pellet.Half the supernatant was filtrated through a cartridge filter (cell-free supernatant).The remaining half was autoclaved (autoclaved supernatant).The sediment was washed twice with a basal medium to remove residual inhibitors from the culture fluid and then resuspended in the basal medium.These fractions were inoculated onto the N. frontalis PNK2 culture.Relative inhibition, H2 production, and pH of the culture fluid were measured.The WV1 culture inhibited cellulolysis and growth in N. frontalis PNK2, P. communis 12A, and Piromyces sp.P1 significantly (p <0.01).The cell suspension of WV1 significantly inhibited cellulolysis and H2 production (p <0.01). Conclusion, significance and impact of study:The results clearly showed that B. fibrisolvens WV1 contained cellassociated inhibitory factor(s) against fungal cellulolysis.Removal of WV1 through immunological methods, such as the introduction of strain-specific immunoglobulins, could facilitate an enhancement in fungal cellulolytic activity within the rumen.