INHIBITION OF THE CELLULOLYTIC ACTIVITY OF NEOCALLIMASTIX-FRONTALIS BY RUMINOCOCCUS-FLAVEFACIENS

A study was made of the antagonistic effect of Ruminococcus flavefacie ns on the cellulolytic activity of Neocallimastix frontalis. An extrac ellular factor inhibiting the cellulolytic activity of the fungus was detected in the bacterial supernatant. The antagonistic factor, which precipitated with ammonium sulphate at 40 % saturation, was temperatur e-sensitive and was destroyed at temperatures above 60-degrees-C. Afte r separation by anion-exchange chromatography, sequential precipitatio n, dialysis and SDS-PAGE, two protein species of 100 and 24 kDa were i dentified as being involved in this antagonistic effect. It is not kno wn whether the proteins are two subunits of a single protein or repres ent two different proteins. The inhibitory factor, which is not a bact erial cellulase, did not affect fungal growth, but it inhibited the ac tivity of the fungal cellulases.