Digestion by Rumen Microorganisms, Hydrolytic Products of Cellulose and the Cellulolytic Enzymes

Kitts, W. D.; Underkofler, L. A.

doi:10.1021/jf60032a007

Cited by 39 publications

(10 citation statements)

References 3 publications

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“…Such low rates of cellulose hydrolysis may well represent enzymic breakdown of non-reducing fractions (xylans, glucosans) associated with relatively undegraded cellulose. Support for this proposal is seen in the chromatographic identification of xylose from an Alphaeel+ rumen microorganism incubation (Kitts & Underkofler, 1954 …”

Section: Discussionmentioning

confidence: 88%

Cellulolysis by Rumen Micro-organisms

Halliwell¹

1957

Journal of General Microbiology

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SUMMARY: The optimal conditions for accurate and reproducible analysis of cellulose hydrolysis by micro-organisms, particularly from the m e n , were determined. Rumen micro-organisms were found to require approximately 50 mg. substrate (cellulose powder) in a p0 hr. incubation at 3 7 ' with 1 ml. of m e n liquor, and a total volume of 8 ml., in static vessels. All types of cellulose or simpler substituted derivatives, from soluble carboxymethylcellulose through insoluble cellulose powder to cotton fibres, are nearly quantitatively hydrolysed by mixed rumen micro-organisms. The effect of the inorganic composition of the medium, of antibacterial agents (thymol, fluoride, toluene) and of concentration procedures on the cellulolytic activity of rumen micro-organisms was examined. Rumen protozoa appear to play a minor role in cellulose degradation; their effective activity is due mainly to closely associated, possibly ingested, bacteria. The validity of the results obtained by various methods of ' cellulase ' assay is discussed.

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Section: Discussionmentioning

confidence: 88%

Cellulolysis by Rumen Micro-organisms

Halliwell¹

1957

Journal of General Microbiology

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“…Much cellulose is digested in the rumen. Cell-free cellulose-digesting extracts of mixed rumen bacteria have been obtained (9), and a multiplicity of cellulases has been demonstrated (7,8).…”

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confidence: 99%

Factors Affecting Cellulolysis by Ruminococcus albus

Smith

Hungate

1973

J Bacteriol

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The factors influencing the digestion of pebble-milled cellulose by enzymes were studied by using several strains of Ruminococcus albus including a mutant characterized by a more eccentric location of its colony in the clearing produced by digestion of the cellulose in the thin layer lining the wall of a culture tube. Most of the cellulase is extracellular. As much as 65% of the cellulose could be digested by the cell-free enzymes provided the quantity of cellulose was small. Fresh enzyme was repeatedly administered or the digestion experiment was arranged in a dialysis bag through which digestion products could diffuse. Cellobiose and, to a lesser extent, glucose inhibited digestion. Pebble-milled filter paper, moist crystalline cellulose from cotton, and dry crystalline cellulose (Sigmacel) were digested, but in decreasing rapidity, respectively. Carboxymethylcellulose was digested more rapidly than pebble-milled cellulose but to approximately the same final extent as judged by Cu reduction values. Cell walls from alfalfa were digested. The enzyme preparation was active over the pH range 6.0 to 6.8 and showed most rapid cellulose digestion at 45 C. Part of the cellulolytic activity was irreversibly destroyed by exposure to oxygen. Much of the enzyme was absorbed on cellulose. The absorption and desorption characteristics, as well as the partial inhibition by oxygen, indicate that multiple enzymes are involved. 729

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“…Enzyme activity was measured as either reduction in the viscosity of CMC or by production of reducing sugar by culture filtrates of the Cellulomonas or Clostridium species. Kitts and Underkofler (1954) determined that rumen fermentation could be arrested at the reducing sugar stage by the addition of toluene, thymol, or sodium fluoride. Cultures so treated produced primarily glucose, which Kitts and Underkofler presume to be the main intermediate of rumen fermentations.…”

Section: Bacteriamentioning

confidence: 99%

“…In some cases, investigators used extracts of rumen preparations to determine the degradability of various cellulosic or lignocellulosic materials. Investigators who tested crude rumen extracts on cellulosic materials include Kitts andUnderkofler (1954), Festenstein (1957), and . These investigators have used various substrates.…”

Section: Cellulasesmentioning

confidence: 99%

“…Halliwell suggested that the high degradation percentages and rapid rates are due to the mixed culture used. The products of degradation are given as glucose from carboxymethylcellulose (Festenstein, 1957) and as soluble reducing compounds (Kitts and Underkofler, 1954;. Halliwell stated that there is no known method of producing a rumen microorganism extract which has the same vigor against whole native lignocellulose or cellulose shown by a whole rumen culture .…”

Section: Cellulasesmentioning

confidence: 99%

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