The cellulase content of 15 species of entodiniomorphid protozoa, mixed bacteria and plant debris isolated from the ovine rumen

Abstract

SummaryThe cellulolytic activity of cell-free extracts of 15 species of entodiniomorphid protozoa grownin vitroand under two conditionsin vitrohas been measured using six different assays with substrates varying in complexity from carboxymethylcellulose to microcrystalline cellulose. Although there were differences between the assays, the highest activities were found inEudiplodinium maggii, Epidinium ecaudatum caudatumandOstracodinium obtusum bilobumwith little or no activity in fiveEntodiniumspp. There was no consistent effect of growth conditions on cellulase content although with protozoa grownin vitrothose grown on grass alone tended to contain more cellulase than those grown on starch and grass.A survey of methods for the release of cellulase from other rumen fractions was made and mild treatment with ultrasound of the fraction suspended in water gave the maximal release of enzyme with the highest specific activity. Using this method 62% of the total rumen cellulase was found in the protozoal fraction and 27% was associated with the plant debris in a normal sheep, fed on hay and oats, with an A-type protozoal population.