Dp. Morgavi et al., EFFECTS OF RUMINAL PROTOZOA ON CELLULOSE DEGRADATION AND THE GROWTH OF AN ANAEROBIC RUMINAL FUNGUS, PIROMYCES SP STRAIN OTS1, IN-VITRO, Applied and environmental microbiology, 60(10), 1994, pp. 3718-3723
An anaerobic rumen fungus, Piromyces sp. strain OTS1, was incubated in
the presence or absence of a mixed, A-type, protozoal population obta
ined from a goat, in a medium containing filter paper cellulose as ene
rgy source and antibiotics to suppress bacterial growth. Fermentation
end products, cellulose degradation, and chitin as an indicator of fun
gal biomass were examined. In the presence of protozoa, total volatile
fatty acids, notably propionate and butyrate, increased, and lactate
decreased. In fungus-protozoan coincubations, formate was not detected
at the end of the experiment and the amount of reducing sugars remain
ed low throughout the incubation period. The fungal growth in the coin
cubations was negatively affected. While protozoal predation on zoospo
res was one mechanism of inhibition, mature fungal cells were also aff
ected. Total cellulose degradation was greater in fungal monocultures,
but the amount of cellulose degraded per unit of fungal biomass was 2
5% larger in the coincubations. The negative effects that the protozoa
l predatory activity had on the fungal growth and subsequently on the
amount of cellulose degraded by Piromyces sp. strain OTS1 were partial
ly attenuated by the protozoal fibrolytic activity or by an enhanced f
ungal activity due to a more favorable environment.