Degradation, cellulase

Filter paper degrading cellulase activity was measured by the author s (39) shaking method using 2 sheets of Toyo filter paper No. 2, 10 mm. X 10 mm. at 40°C., pH 5.0. Complete degradation was shown by + + ++. 

With the view of elucidating the cellulolytic component responsible for the degradation of plant cell wall, Imai and Kuroda (16) investigated the breakdown of cell walls of unicellular potato with T. viride cellulase. Potato unicells prepared with Rhizopus CSE were incubated with the fraction containing filter paper degrading cellulase and CMCase, which was obtained from T. viride cellulase preparation by using a cellulose column akin to the author s gauze column method. 

Furthermore, T. viride cellulase was fractionated by Amberlite CG 50 column into filter paper degrading cellulase, CMCase, and xylanase fractions. It was conclusively shown that only filter paper degrading cellulase contributed to the degradation of cell walls of unicellular potato. 

The catalytic and non-catalytic domains of hemiceUulases have been elucidated, which reveal the principles of catalysis and specificity for these enz5mies (28). Also, the production o cellulase in microorganisms has been thoroughly investigated (29). For example, the filamentous fungus Trichoderma reesei produces and secretes superabimdant amounts of enzymes that act S5mergistically to degrade cellulase and related biomass components. 

Microbiological degradation Cellulase - enzymes also cause hydrolysis of the p-glucoside linkages. This possibility has found increasing interest to use cheap biomass as a feed medium for biotechnological processes. 

However, if theoritically, the combination of pectinases to cellobiohydrolases plus endo-glucanases should release more than 80% of all polysaccharides from the cell walls (according to Voragen and al. [4]), in industrial conditions, we arrive almost at this level of degradation but only for the pectin. Commercial enzymes preparations contain pectinases, hemicellulases and cellulases. 

The types of spoilage caused by bacteria in fruits and vegetables are diverse they include sensory changes, degradation of compounds, and formation of new substances such as acids, volatile compounds, and polymers. For example, the bacteria produce a set of enzymes such as pectinases, cellulases, proteases, and others that causes maceration and softening of tissue. Off-flavor development is common in contaminated tissues, caused by volatile compounds produced by microflora (Jay 1992). 

Fig. 38.—13C-N.m.r. Spectrum of A, Partly Depolymerized O-Methylcellulose (d.s. 2.8) in CDC13 at 30° (R, signal due to reducing-end residue Me, O-methyl inset lines represent chemical shifts of corresponding carbon atoms in methyl hepta-O-methyl-jS-cellobioside) and of B, O-Methylcellulose (d.s. 0.7), Partially Degraded by Cellulase, in D20 at 30°. (S represents a 13C nucleus bonded to an OMe group inset lines give the chemical shifts of corresponding carbon atoms in methyl /3-cellobioside.)...

The titers of cellulase activities found in anaerobic digesters, when compared to the few other "hydrolytic environments" for which analytical data are available, are strikingly low. Table III shows such values for filter paper and carboxymethyl cellulose degrading activities. This evidence seems to indicate that the cellulose degrading enzymes in ... 

Figures 1 and 2 show positive correlation, although of varying degrees of goodness of fit, between the specific activities of endo ucanase, exoglucanase, and -glucosidase activities with the cellulose composition and degradation in digester feed, respectively. These data indicate a direct relationship between the cellulose content in the feed and cellulase enzyme complex production by the digester consortia. In this system, as in many others studied, cellulose is an effective inducer of cellulase secretion (67,68),...

Figure 2. Comparisons of cellulose degradation of the MSW feedstock with specific cellulase enzyme activities in sludge from 7 CSTR digesters operated under different retention times and various conditions of nutrient limitation.

RunUnococcus albus and Ruminococcus flavefadens. These bacteria are important cellulose-degraders found in the rumen of cattle and sheep (2). Most isolated strains ferment cellulose and xylan and all ferment cellobiose. Fermentation of glucose and some other carbohydrates depends on the particular strain. R flavefadens and B. succinogenes can ferment the highly ordered crystalline cellulosic su trates but R albus cannot. No evidence has been found for extracellular cellulase production by R albus, but Ohmiya et al. purified cellobiosidase from this culture 17). Laboratory growth of R albus has been conducted at pH 7.0 and 37 C. 

---