Bibliography: leaves 139-167 The aim of this project was to identify an enzyme responsible for the metabolism of oxalate which would be suitable for degrading oxalate in the rumen, and clone and characterise that gene.

Call number: LD2668 .T4 1961 H39

Call number: LD2668 .T4 1955 H36 / Master of Science

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Colony counts of proteolytic ruminal bacteria in the order of 1 x 10⁹ organisms per gram of whole rumen contents and total colony counts in the order of 2 to 3 x 10⁹ organisms per gram were obtained from rumen contents of cattle fed a maintenance ration of hay and grain. The proteolytic counts averaged 381 of the total counts. An anaerobic, differential medium characterizing proteolytic colonies by clear zones in an opaque skim milk suspension was utilized. Proteolytic isolates were assigned to the following taxa; Butyrivibrio fibrisolvens, Succinivibrio dextrinosolvens, Selenomonas ruminantium var. lactilyticas, Borrelia, Bacteroides (butyric acid-producing R•2 group of Bryant), and selenomonad-like organisms similar to B-385 group of Bryant. 1 A portion of the Ph.D. dissertation by the senior author. 2 Present address: Division of Natural Sciences, Susquehanna University, Selinsgrove, Pennsylvania. Proteolysis in the ruminal fermentation may benefit the host animal if the resulting products are later synthesized to digestible microbial proteins of higher biological value than the feed protein, or conversely this activity may be detrimental because of net protein loss. In spite of the nutritional significance of this activity the proteolytic ruminal bacteria have received relatively little attention as a physiological group. Studies have largely been restricted to observations of the degradation of gelatin or casein incidental to other studies of ruminal organisms. Gelatin proteolysis was reported among isolates from the rumen by Bryant (1951), Bryant and Burkley (1953a, 1953b, 1953c), Bryant and Small (1956a), Bryant et al. (1958a), Hamlin and Hungate (1956), Buhtanen and Gall (1953), Hungate (1957), and Hann et al. (1954). Bryant and Doetsch -- (1954) also reported isolates which attacked casein but not gelatin and Bryant (1956) reported a strain of Selenomonas ruminantium which digested casein but not gelatin. Bryant (1959) revealed the paucity of information on the proteolytic flora of the rumen in his excellent review of the bacteriology of the rumen. A casein medium designed for the isolation of proteolytic ruminal bacteria was described by Appleby (1955). Blackbum and Hobson (1960a) found proteolytic activity in all fractions of rumen contents (protozoa, large bacteria and small bacteria) and they initiated isolation of proteolytic bacteria from the ovine rumen (Blackburn and Hobson, 1960b). Fulghum (1958) described the development of two anaerobic, differential media for the isolation and enumeration of proteolytic ruminal bacteria, these media were developed through modification of the media of Hamlin and Hungate (1956) and ling and Smith (1955), and of the medium used by Donovan and Vincent (1955) for studying proteolytic organisms from milk. Fulghum (1958) found the optimum level of clarified rumen fluid added to these media to be 401. Colonies of proteolytic organisms in these media were characterized by clear zones in opaque skim milk or plant protein suspensions in the media. Plant proteins failed to maintain a uniform opacity and were therefore of limited value in delineating the proteolytic segment of the flora even though the plant proteins stimulated total counts by a factor of from three to five. Earlier Fulghum et al. (1958) reported that dispersion of whole rumen contents in anaerobic diluting fluid in a blendor increased total counts by a factor of four when compared with total counts obtained from rumen fluid samples which were diluted by shaking in anaerobic diluting fluid. Proteolytic counts were the same from both inocula. In later studies (Fulghum, 1958), proteolytic counts were also found to be increased by a factor of four when dispersed whole contents were compared with shake dilutions of rumen fluid. Proteolytic and total counts were found to be slightly higher in the dorsal sac of the rumen than in the ventral sac, although this phenomenon was variable with regard to time of sampling following feeding of animals. Similarly, the ratio of proteolytic to total counts varied at different times following feeding. The proteolytic flora remained constant while the total counts varied. The sequence of fluctuation was different in each individual animal. / Ph. D.

Ten strains of anaerobic, gram negative, monotrichous, butyric acid-producing curved rods have been isolated from ingesta of the bovine rumen. These 10 strains of butyrivibrio represented 1/5 of all isolates at 1 x 10⁻⁸ dilutions. Morphological and physiological characteristics of the 10 strains and a strain isolated by gill and king (1958) have also been studied. No two of the isolates were identical in all reactions. Most of the organisms produced a large amount of butyric and some lactic, formic, propionic and succinic acids with the utilization of acetic acid in a rumen fluid glucose medium. The fermentation carried on by these organisms was sensitive to most tested environmental changes. Studies with buffered rumen fluid-glucose media demonstrated a shift of the fermentation products with pH. Addition of fatty acids to this medium indicated that these organisms were active in the conversion of acetate and possibly propionate to butyrate. Two strains apparently had the ability to produce propionate at the expense of lactate. The results of the fermentation tests in 98 per cent rumen fluid medium showed that the tested strains used acetic (plus formic) or lactic (plus succinic) to produce butyric or propionic acid, and produced higher concentrations of fatty acids under a carbon dioxide atmosphere than under nitrogen. When rumen fluid and acetic acid were absent all strains had the ability to produce either formic or acetic acid. / Master of Science

One or more factors which occur in bovine rumen fluid stimulate the growth of a strain of Butyrivibrio. The stimulating material is heat stable, organic in nature and non-dialyzable. It cannot be extracted from rumen fluid with lipid solvents and is retained in part on anion and cation exchange resins. It can be eluted from the resins with strong acid. It is stable to enzymatic hydrolysis by trypsin. Granular mucin or bovine saliva will partially replace the stimulatory activity. The part of the material which was not replaced by mucin did not appear to be any compound that is commonly used to stimulate bacterial growth. The presence of a possible inhibitor for the growth of a strain of Butyrivibrio was demonstrated. / Master of Science