Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing compound containing saccharide radical
Patent
2000-02-14
2000-11-14
Lilling, Herbert J.
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing compound containing saccharide radical
435201, 435209, 435263, C12P 1904, C12N 926, C12N 942, D06M 1600, C08B 106
Patent
active
061468584
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of cellulose derivatives using cellulose pretreated with endoglucanases.
A reduction in the amount of alkali to be used by using cellulases in an enzymatic pretreatment stage has been described by Michels and Meister (DE 4 440 245 C1). Cellulases are enzyme complexes in which enzymes having different catalytic activities are combined: endoglucanases (EC 3.2.1.4), exoglucanases, which are also known as cellobiohydrolases (EC 3.2.1.74, EC 3.2.1.91) and .beta.-glucosidases (EC 3.2.1.21). Those enzyme activities together decompose cellulose completely to glucose, whereas each on its own catalyses only partial steps of the decomposition. Endoglucanases, for example, cleave only endogenous .beta.-1,4-glycosidic bonds in the amorphous regions of the polymer.
Surprisingly, endoglucanases can also be used alone in a similar pretreatment step for reducing the amount of alkali required. Moreover, the use of endoglucanases offers two important advantages in comparison with cellulases. Firstly, pretreatment with cellulases leads to a considerable loss of cellulose substrate to a marked reduction in the degree of polymerisation (DP value) and to a loss of cellulose substrate. Secondly, the cellulase activity is inhibited by soluble oligomeric decomposition products, which considerably restricts the possibility of the repeated use of a cellulase solution. That difference can be attributed to the different catalytic activities of the two enzymes.
Accordingly, the invention relates to a process by means of which cellulose of a suitable commercial quality is pretreated with endoglucanases prior to chemical conversion to commercial cellulose derivatives. With the aid of that pretreatment process, the degree of alkalisation of the cellulose and hence also the amount of chemicals used in the after-treatment steps can be reduced considerably. The process comprises treating the cellulose enzymatically with endoglucanases before it is introduced into the industrial manufacturing process. The cellulose pretreated in that manner and separated from the enzyme solution is hereinafter referred to as "activated". The cellulose derivatives prepared by the chemical conversion of activated cellulose are comparable with today's industrially manufactured products.
According to the invention, the process is as follows: incubation at a certain temperature and for a certain period of time in a suitable buffer system. mixture consisting of the buffer and the enzyme. industrial conditions, but substantially less alkali is required for the reaction.
The conditions for the enzymatic pretreatment in step (A) can be varied as desired. Factors that affect the enzymatic pretreatment are: and plants, preferably from the fungi Trichoderma reesei, Humicola insolens and bacteria of the genera Bacillus, Cellulomonas, Sporocytophaga, Cytophaga, Clostridium. The use of Denimax Ultra L.RTM. (Novo Nordisk) is especially preferred. mM, especially preferred range 50 mM sodium acetate or potassium phosphate according to the required buffer range. Other buffers or buffer/solvent mixtures are also in accordance with the invention. from pH 4 to pH 10, especially preferred range from pH 5 to pH 7.5. g:0.5 ml to 1 g:1000 ml, preferably from 1 g:5 ml to 1 g:100 ml, especially from 1 g:10 ml to 1 g:30 ml. 0.01 to 50%, preferred range from 1 to 30%, especially preferred range from 3 to 12%. 20 to 80.degree. C., especially preferred range from 50 to 60.degree. C. from 1 to 24 hours, especially preferred range from 2 to 3 hours. preferred range from 10 to 2000 rpm, especially preferred range from 200 to 300 rpm.
The effect of those factors on the enzyme activity is known per se. Moreover, it has been shown that the cellulolytic enzymes obtained from various species have different degrees of affinity and activity. Changing those factors in the pretreatment process will, therefore, affect the activation of the cellulose. That in turn leads to changes in the degree of substitution of the chemically reacted cellulo
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Berendes Frank
Engelhardt Jurgen
Foster John
Koch Rainhardt
Koch Wolfgang
Gil Joseph C.
Lilling Herbert J.
Preis Aron
Wolff Walsrode AG
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