%0 Journal Article %A Blackburn, T. H. %A Hobson, P. N. %T Proteolysis in the Sheep Rumen by Whole and Fractionated Rumen Contents %D 1960 %J Microbiology, %V 22 %N 1 %P 272-281 %@ 1465-2080 %R https://doi.org/10.1099/00221287-22-1-272 %I Microbiology Society, %X SUMMARY: The proteolytic activity of the whole rumen fluid of sheep does not depend on the diet of the animals. The optimum pH value for proteolysis lies between 6 and 7, with an irregular maximum at about pH 6·5. All fractions of rumen contents (protozoa, large bacteria and small bacteria) show activity. Proteolytic activity can be demonstrated in the supernatant liquid after disruption of the microorganisms. The proteolytic activity of the whole rumen fluid was enhanced by cysteine at 0·06 and 0·006 % (w/v) unless the rumen fluid had been collected and processed under highly anaerobic conditions. Potassium cyanide and ascorbic acid were also slightly stimulatory, but sodium thiosulphate, thioglycollic acid, sodium sulphide and Fe++, Ca++ and Mg++ ions had no effect. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-22-1-272