Hydrolysis of Avicel

B) Synergistic effect on the hydrolysis of Avicel by CBH I/CBH II (pH 5.0, 37°C). CBH I and CBH II in different combinations (abscis) are mixed with Avicel (30 mg/ml). The total enzyme concentration is always 10 /iM and reducing sugars in the supernatant measured after 45 min incubation. 

D) Synergistic effect on the hydrolysis of Avicel by core I/CBH II. Same conditions as in (B). 

Table VII. Hydrolysis of Avicel by Purified Cellulase Components, Alone and in Combination...

The changes in enzyme protein concentration and activities in the solution during hydrolysis of Avicel were measured as funetions of the addition of Tween 20 (Fig. 7). 

Fig. 6 Effect of Tween 20 on enzymatic hydrolysis of Avicel with 8% dry sohd loading at 15 FPU + 15 CBU/g cellulose enzyme loading...

Fig. 7 Changes in free protein concentration and relative enzyme activities in solution during enzymatic hydrolysis of Avicel at 8% dry solid loading with and without Tween 20 addition...

As shown above, the improvement upon addition of surfactant of hydrolysis of Avicel was much lower than that of pretreated CWR. This result agreed well with findings by Eriksson et al. [7] who reported that surfactants and BSA were both viewed as preventing nonproductive adsorption of cellulase on lignin. However, the contrary findings reported that the non-ionic surfactants could enhance the hydrolysis of cellulose such as Sigmacell 100 and Avicel and act differently from proteins [22, 25, 38]. Therefore, more research needs to be done to solve this discrepancy and better imderstand the mechanisms of additive effect. 

Synergistic Action of Ex-1 with other Endocellulases on the Hydrolysis of CMC and Avicel. The synergistic action of Ex-1 with F-l was investigated in the hydrolysis of both CMC and Avicel. For comparison, we investigated a similar action between S-l and F-l. The results are shown in Table V. 

The synergistic effect caused by a mixture of a typical endocellulase, F-l (CMCase), and an endocellulase of lower randomness (Avicelase) is slightly smaller than that caused by a mixture of F-l and Ex-1 (an exocellulase of Avicelase type) in the hydrolysis of both CMC and Avicel. This may be explained by the postulation that this kind of synergistic effect should be caused by the cooperation between cellulase components of extremely different types of hydrolysis. Consequently, the... 

Amylodextrin is the homogeneous product of prolonged hydrolysis of starch below Tgz, terminating in the crystalline equivalent of Avicel and approximating 25 glucose monomers. The hydrolysis is normally at room temperature over intervals of months, wherein the amorphous regions are degraded and the starch crystallites are left intact. Unlike Avicel crystallites, starch crystallites may be disrupted by stress (Kerr, 1950). 

In 1972 Ogawa and Toyama (56) purified three components— A-I-a, A-I-b, and A-II-1—which were adsorbed on a gauze column during purification from Cellulase Onozuka P1500, a commercial preparation of T. viride cellulase. These three components had molecular weights of 32,000, 48,000, and 48,000 as determined by gel filtration and contained 7-16% carbohydrate. Each is reported to carry out the random hydrolysis of CM-cellulose and to degrade hydrocellulose (Avicel) and cellooligosaccharides except for cellobiose. The order of reactivity toward either cotton or Avicel was A-II-1 > A-I-b > A-I-a. The proteins adsorbed on cellulose comprised 38% of the total cellulase protein. 

As currently understood, the cellulase complex contains the following components (listed in the order in which their action on cellulose occurs) 1. Ci is an enzyme whose action is unspecified. It is required for the hydrolysis of highly oriented solid cellulose (Cotton, Avicel, etc.) by 0-1 — 4 glucanases. 

Batch Hydrolysis of Pretreated Sugar Cane Bagasse and Avicel... 

Enzyme activity loss because of non-productive adsorption on lignin surface was identified as one of the important factors to decrease enzyme effectiveness, and the effect of surfactants and non-catalytic protein on the enzymatic hydrolysis has been extensively studied to increase the enzymatic hydrolysis of cellulose into fermentable sugars [7, 9 19]. The reported study showed that the non-ionic surfactant poly(oxyethylene)2o-sorbitan-monooleate (Tween 80) enhanced the enzymatic hydrolysis rate and extent of newspaper cellulose by 33 and 14%, respectively [20]. It was also found that 30% more FPU cellulase activity remained in solution, and about three times more recoverable FPU activity could be recycled with the presence of Tween 80. Tween 80 enhanced enzymatic hydrolysis yields for steam-exploded poplar wood by 20% in the simultaneous saccharification and fermentation (SSF) process [21]. Helle et al. [22] reported that hydrolysis yield increased by as much as a factor of 7, whereas enzyme adsorption on cellulose decreased because of the addition of Tween 80. With the presence of poly(oxyethylene)2o-sorbitan-monolaurate (Tween 20) and Tween 80, the conversions of cellulose and xylan in lime-pretreated com stover were increased by 42 and 40%, respectively [23]. Wu and Ju [24] showed that the addition of Tween 20 or Tween 80 to waste newsprint could increase cellulose conversion by about 50% with the saving of cellulase loading of 80%. With the addition of non-ionic, anionic, and cationic surfactants to the hydrolysis of cellulose (Avicel, tissue paper, and reclaimed paper), Ooshima et al. [25] subsequently found that Tween 20 was the most effective for the enhancement of cellulose conversion, and anionic surfactants did not have any effect on cellulose hydrolysis. With the addition of Tween 20 in the SSF process for... 

The enzymatic hydrolysis and sampling procedures for Avicel was the same as described in Enhancement of Enzymatic Hydrolysis of Pretreated CWR by Additives. Based on the experimental result fiom Effect of Tween 20 Loading on Enzymatic Hydrolysis of Pretreated CWR, the ratio of Tween 20 to Avicel was decided to be 0.1 g Tween 20 to 1 g Avicel. A homogeneous aliquot of I ml was withdrawn at start and after 1, 2, 4, 8, 24, 48, and 72 h of hydrolysis. The aliquots were treated as Effect of Tween 20 and BSA on Enzyme Protein Concentration and Activity to obtain 500-ul supernatant samples. The... 

Figure 1.7 TEM micrographs of nanocrystals obtained by sulfuric acid hydrolysis of (a) cotton (b) avicel and (c-e) tunicate cellulose. The insets of (a) and (b) provide higher resolution images of some characteristic particles. Reprinted with permission from [47, 53]. Copyright 2010 John Wiley and 2008 American Chemical Society.

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