Exocellular Carbohydrase Formation by Rumen Holotrich Ciliates

SYNOPSIS Exocellular carbohydrase activity was detected, in the absence of cell lysis, in cell‐free culture supernatant fluids of rumen holotrich ciliates after incubations in buffer systems of varying tonicity, from cell suspensions that were isolated by various technics, and in which bacterial activity had been suppressed by antibiotics. The kinetic characteristics of the holotrich invertases and β–glucosidase from Dasytricha , although having interspecies variations, were the same for the intra‐ and extracellular form of the enzyme. The properties of the invertase activity present in cell‐free rumen contents resembled those of the exocellular enzymes formed by the holotrichs. Invertase activity in the in vitro culture supernatant fluid of Dasytricha ruminantium increased throughout the incubation period and was influenced by the initial pH, temperature, sucrose concentration, and inoculum size. Exocellular holotrich carbohydrase activity was increased when the incubation substrate was not readily utilized by the protozoa. Intracellular carbohydrase activity was also influenced by the carbohydrate substrate.