Cellulose hydrolysis products from

As further evidence, we demonstrated by paper chromatography that hydrolysis products from cellooligosaccharides by Ex-1 are Gi and G2 from G3, and Gi, G2, and G3 from G5, but only G2 from G4, Ge, CMC, cellodextrine, and insoluble cellulose such as Avicel, swollen cellulose, absorbent cotton, and filter paper (Figures 13 and 14). However, G3 was formed from G6 when Ex-1 was incubated with a mixture of G6 and Gi. There is no indication that G6 was split by this cellulase into G3 plus G3, but rather that G2 produced from G6 was transferred immediately to Gi to form G3. The results are shown in Figure 15. 

Figure 14. Paper chromatogram of the hydrolysis products from higher cellulose substrates by Ex-1. Developed by the descending technique for 96 hr at room temperature on Whatman No. 1 paper, using 1-butanol pyridine water (6 4 3, v/v) as a solvent (S) standard, (Gt) glucose, (Gz) cellobiose, (Gs) cellotriose, (Gu) cellotetraose, (G5) cellopentaose, (G6) cellohexaose final enzyme concentration 2.82 X 10 2%.

Figure 4 Comparative analysis of glucose and gluconic acid production from cellulose demonstrating inhibition of cellulolytic enzymes by cellulose hydrolysis products...

Cane and beet sugars can be extracted in almost pure form and used as highly reactive chemical intermediates or for edible purposes. Ntuaerous other sugars have been extracted from plant products or produced as hydrolysis products from hemicelluloses, celluloses, and starches. 

About half of the wodd production comes from methanol carbonylation and about one-third from acetaldehyde oxidation. Another tenth of the wodd capacity can be attributed to butane—naphtha Hquid-phase oxidation. Appreciable quantities of acetic acid are recovered from reactions involving peracetic acid. Precise statistics on acetic acid production are compHcated by recycling of acid from cellulose acetate and poly(vinyl alcohol) production. Acetic acid that is by-product from peracetic acid [79-21-0] is normally designated as virgin acid, yet acid from hydrolysis of cellulose acetate or poly(vinyl acetate) is designated recycle acid. Indeterrninate quantities of acetic acid are coproduced with acetic anhydride from coal-based carbon monoxide and unknown amounts are bartered or exchanged between corporations as a device to lessen transport costs. 

The acid-oxidant method is based on the idea that the hydrolysis of cellulose might be continuously determined from the rate of carbon dioxide evolution. Since, under controlled conditions, the rate of evolution of carbon dioxide is proportional to glucose concentration, it should be possible to follow the course of cellulose hydrolysis by means of the rate of carbon dioxide evolution provided that the sole final product of hydrolysis of cellulose is glucose. The latter assumption appears to be justified where the sample is reasonably pure. 

The advances made in enzymatic hydrolysis of cellulosic materials (14) are also of interest. This technology involves only moderate temperature processes in simple equipment which promises to be of significantly lower capital cost than the pressure equipment associated with conventional acid wood hydrolysis processes. All of these considerations combined to lead us to study processes for ethanol production from wood, especially in an effort to obtain data for material and energy balances, and possibly for the economics. 

In addition to the variations in the LHC composition that occur from species to species, each species has its extractives, which include resins and waxes. These constituents are capable of interfering with cellulose hydrolysis because of their hydrophobic nature. Tannins and other highly reactive materials are constituents of some woody species. When LHC is obtained from nonwoody (herbaceous) species, the range of interfering constituents increases greatly. Sugars, starches, dextran, carotenoids, and many isoprenoids are to be found. Operators of a cellulose hydrolysis process that uses municipal solid waste as its biomass resource may experience seasonal variations in composition and chance inclusion of crankcase oil and other products that inhibit enzymes or kill yeast. 

Specific hydrolysis products obtained from both cellulose and cello-dextrins by cellobiohydrolase and endoglucanases were analyzed by low pressure liquid chromatography using water as the sole eluent (25,40). 

The following gives a brief compilation of procedures to determine hexenuronic acids in cellulosic pulp samples. The common methods are based on hydrolysis of HexA moieties from pulp, either enzymatically or chemically, with subsequent quantification of the hydrolysis products either directly or after chemical conversion into UV active compounds. A comparison of these three methods is given by Tenkanen et al. [136]. For comparison rather than exact determination of HexA, e.g., during bleaching stages, the diffuse reflection UV VIS method can be applied [137]. A photoacoustic FTIR procedure based on chemometric analysis has been described as well [138]. In Table 3, the available methods to analyze HexA moieties in cellulosic material are summarized. 

The filamentous fungi investigated showed coinduction of cellulolytic and xylanolytic enzymes. During growth on cellulose, products from the hydrolysis of cellulose also induced production of xylanolytic enzymes, and during growth on xylan, products from the hydrolysis of xylan also induced the production of cellulolytic enzymes. 

A 72-h hydrolysis profile of a 10% acetic acid-pretreated softwood substrate (Fig. 1) represents a typical enzymatic cellulose hydrolysis course with the majority of the cellulose (up to 70%) broken down within the first 24 h. However, the conversion of the remaining cellulose ( 30%) was incomplete, even after another 2 d of incubation. The decrease in the hydrolysis rate in the latter phase is likely owing to accumulation of end products. To demonstrate that the end products played a major inhibitory role, we removed the produced sugar from the hydrolysate through ultrafiltration. Fresh buffer was then added to the retained protein and the residual substrate to attain the initial volume, and the hydrolysis was continued under the same condition. As shown in Fig. 1, significant increases in the hydrolysis rate were observed after the sugar removal at both 24 h and 48 h of incubation, with complete hydrolysis attained after 48 h and 60 h of incubation respectively. 

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