Some properties of the endo-(1 → 4)-β-D-glucanase synthesized by the anaerobic cellulolytic rumen bacterium Ruminococcus albus

Authors:
  • TWThomas M. Wood
    Thomas M. Wood
  • CWCatriona A. Wilson
    Catriona A. Wilson
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Abstract
The extracellular and cell-bound cellulase (CM-cellulase) elaborated by the rumen bacterium Ruminococcus albus SY3 in synthetic medium was an endo-(1 → 4)-β-glucanase in that (i) it produced a rapid fall in the degree of polymerisation (1900 → 300) of H3PO4-swollen cellulose, while causing only 0.5% hydrolysis, and (ii) it released large amounts of cellotriose and smaller amounts of cellotetraose from H3PO4-swollen cellulose. The enzyme appeared in a wide range of molecular weights, which varied according to the culture conditions, but nevertheless focused at pH 6.0–6.1 in all cases in a pH gradient supported in a polyacrylamide gel. Cell-bound enzyme, which was of very large molecular weight (> 1.5 × 106), was excluded from the polyacrylamide gel. Under certain conditions, cellulose swollen in H3PO4 was hydrolysed extensively, but highly ordered cellulosic substrates were poorly hydrolysed. The enzyme acted synergistically with an endwise-acting cellobiohydrolase from the fungus Trichoderma koningii in solubilizing a microcystalline wood α-cellulose preparation (Avicel): the same cooperation was not apparent when Avicel was swollen in H3PO4 or when cellulose in the form of cotton fibre was used.

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