Cellulase digestibility

A convenient procedure for assessing the digestibility of forages is the cellulase digestibility technique. This was refined by Jones and Hayward (1973) at the Welsh Plant Breeding Station (WPBS) in Aberystwyth (since 1992, the Institute for Grassland and Environmental Research). It was later extended to a two-stage procedure with a pepsin pre-treatment (Jones and Hayward, 1975). 

See the discussion in Chapter 4, Cellulase digestibility. This method is based on that of Jones and Hayward (1973 and 1975). 

Jones, D.I.H. and Hayward, M.V. (1973) A cellulase digestion technique for predicting the dry matter digestibility of forages. Journal of the Science of Food and Agriculture 24, 1419-1426. 

In the reported structures of products of cellulase digestion of xyloglucans from different sources, there has been considerable variation that may reflect different action-patterns of enzyme preparations as much as actual differences in the structures of the polysaccharides. On reaction of xyloglucan from the walls and culture medium of suspension-cultured, sycamore cells,26,27 four major oligosaccharide products were isolated. Stuctures were proposed for the heptamer (Z) and the nonamer (3). 

From the results of cellulase digestion and the characterization of a number of oligosaccharides, an improved partial structure for the runner bean cell wall xyloglucan was proposed (O Neill and Selvendran, 1985b). It would appear that the xyloglucan does not contain a simple repeating unit but is composed of a block-type structure that is commonly encountered in plant polysaccharides (Stephen, 1983). 

Cultures grown four days in shake flasks on T. viride cellulase digest of Solka Floe (filtered, pH adjusted to 5.0, sugar concentration 18 mg./ml., 0.03% urea and 0.01% yeast extract added). 

Cellulase-producing bacteria include CelMomonas, Clostridium, Pseudomonas, Streptomyces, Thermonospora, and Ruminococcus, but bacterial cellulases digest cotton fibers to lower levels compared to amorphous celluloses (Ray et al., 2006). Cellulases have two functionally distinct domains in their structure, namely catalytic domain and cellulose substrate binding domain, linked by an interdomain, glycosylated linker peptide at either the N or the C terminal of the protein cellulose binding domains exhibit different affinities, specificities, some binding to crystalline cellulose, while others restrict themselves to the disordered regions. Catalytic domain has an active site in the shape of a tunnel or cleft where hydrolytic reactions take place (Cavedon et al., 1990 Lee et al., 1996). 

Jeoh T, Ishizawa Cl, Davis ME, Himmel ME, Adney WS, Johnson DK. (2007). Cellulase digestibility of pretreated biomass is limited by cellulose accessibility. Biotechnol Bioeng, 98(1), 112-122. 

G. C. Marten, J. L. Halgerson, and D. A. Sleper, Near Infrared reflectance spectroscopy evaluation of ruminal fermentation and cellulase digestion of diverse forages. Crop ScL, 28 163-167 (1988). 

Tsai, G. J., Zhang, S. L. Shieh, P. L. (2004). Antimicrobial activity of a low-molecular -weight chitosan obtained from cellulase digestion of chitosan. J Food Protec., 67, 396-398a. 

Tsai, G. ]., Wu, Z. Y. Su, W. H. (2000). Antibacterial activity of a chltoollgosaccharlde mixture prepared by cellulase digestion of shrimp chltosan and Its application to milk Journal of Food Protection, 63, 747-752. 

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