The Cultivation of Rumen Oligotrich Protozoa

Abstract

Various factors influencing the life of rumen protozoa, Entodinium species, were studied.Optimal conditions for entodinial survival were determined for the following factors : Temperature, 38-40°; pH, 6.0-7.0; redox potential, -250 to -400 mV ; osmotic pressure , 0.7-1.0% NaCI equivalent.The influence of various compounds formed by rumen microorganisms was examined and toxic levels were found; ammonia had a harmful effect on the protozoa above the level of 3 mmol/100 ml; methylamine, histamine, and formate above 10 mmol/100 ml; methanol and ethanol above 30 mmol/100 ml. Acetate, propionate, butyrate, and lactate had no deleterious effect within the limits tested.In addition, the influence of antibiotics is described.One hundred and thirty years have passed since rumen protozoa were discovered, and a number of studies have been made particularly regarding the nutrition and physiology of the host animal ; information from these studies was systematically summarized by HUNGATE (1). It is generally accepted that the protozoa participate in the digestion inn the rumen and that the bodies of the protozoa are an important source of protein for the ruminant.However, knowledge is incomplete as to the exact role played by these protozoa, incomplete as to the significance of these organisms for the host. Further investigation into the biochemistry of rumenn protozoa has been hampered in a large part due to the lack of pure cultures.Many attempts to cultivate rumen protozoa in vitro have been made inn the last hundred years. Since the first notable advance made by HUNGATE (2, 3), who cultured oertain oligotrich species for over a year, various investigators have been successful in maintaining several genera of oligotrich andd holotrich protozoa outside the host for extended periods. However, the populationn densities reported have been low, compared with those in the rumen, and the 305

A Method of Obtaining Axenic Rumen Ciliate Protozoa

“…Viable bacteria concentrations were determined by inoculating duplicate 1.0, 0.1, and 0.01 ml quantities in media A, B, and C of COLEMAN (2). Medium C supported growth better than A or B. Aliquots from dilutions in the sterile reduced salts solution of BRYANT and BURKEY (7) were transferred to Medium C and used to determine the initial concentration of bacteria. All bacterial cultures were incubated for 5 days at 37°.…”