The Effect of Various Concentrations of Antinutrient Gossypol on the Adherence of Anaerobic Rumen Fungi to Cellulose in Culture

It has been reported that gossypol toxicity in ruminants and in other experiments that gossypol inhibits rumen microbial growth and fermentation by rumen bacteria and rumen protozoa. A further experiment in vitro was conducted to investigate whether the presence of gossypol may inhibit attachment by the rumen fungi. Antinutrient gossypol has been known to depress dry matter (DM) loss, gas production, altered volatile acid (VFA) concentration, survival of mixed rumen bacteria, and protozoa in culture. However, mixed rumen microbes appeared to adapt to the presence of the gossypol in culture. It is still unclear whether the rumen fungus was also affected by the gossypol. An experiment was conducted to investigate the attachment of rumen fungus to cellulose in the presence of gossypol in a consecutive batch culture system. A modified version of medium 2 was prepared under anaerobic conditions using O2-free CO2. The results of this experiment indicated that the total count of 14C-labelled fungus strain RE1 attached to cellulose in the control treatment increased as times of incubation increased. However, the presence of gossypol 0.1 mM decreased (p<0.05) the attachment of the rumen fungus to cellulose. It was concluded that the presence of gossypol in culture affects the life cycle of the rumen fungi possibly through binding of gossypol to attachment receptors on the fungal surface.