Recent developments on cellulases and carbohydrate-binding modules with cellulose affinity

Hildén, Lars; Johansson, Gunnar

doi:10.1007/s10529-004-4579-8

Cited by 105 publications

(42 citation statements)

References 101 publications

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“…To hydrolyze cellulose, endoglucanases locate surface sites randomly along the cellodextrin and insert a water molecule in the intramolecular -1,4-glucosidic bonds, creating a new reducing and non-reducing chain end pair; exoglucanases processively cleave cellulose chains at the ends to release cellobiose, and -glucosidases convert cellobiose to glucose and thus relieve the system from end-product inhibition [12]. However, the division into endo-and exoglucanases in many cases is not absolute and may have the risk of over-simpliWcation [2,10,11,14,29,30]. A processive endoglucanase in ThermobiWda fusca E4 has been documented [14], and it has been suggested that exoglucanases could exhibit some endoglucanase activity due to temporary conformational structural changes [33,38].…”

Section: Introductionmentioning

confidence: 99%

Study of cellulases from a newly isolated thermophilic and cellulolytic Brevibacillus sp. strain JXL

Liang

Yesuf

Schmitt

et al. 2009

J Ind Microbiol Biotechnol

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A potentially novel aerobic, thermophilic, and cellulolytic bacterium designated as Brevibacillus sp. strain JXL was isolated from swine waste. Strain JXL can utilize a broad range of carbohydrates including: cellulose, carboxymethylcellulose (CMC), xylan, cellobiose, glucose, and xylose. In two different media supplemented with crystalline cellulose and CMC at 57 degrees C under aeration, strain JXL produced a basal level of cellulases as FPU of 0.02 IU/ml in the crude culture supernatant. When glucose or cellobiose was used besides cellulose, cellulase activities were enhanced ten times during the first 24 h, but with no significant difference between these two simple sugars. After that time, however, culture with glucose demonstrated higher cellulase activities compared with that from cellobiose. Similar trend and effect on cellulase activities were also obtained when glucose or cellobiose served as a single substrate. The optimal doses of cellobiose and glucose for cellulase induction were 0.5 and 1%. These inducing effects were further confirmed by scanning electron microscopy (SEM) images, which indicated the presence of extracellular protuberant structures. These cellulosome-resembling structures were most abundant in culture with glucose, followed by cellobiose and without sugar addition. With respect to cellulase activity assay, crude cellulases had an optimal temperature of 50 degrees C and a broad optimal pH range of 6-8. These cellulases also had high thermotolerance as evidenced by retaining more than 50% activity at 100 degrees C after 1 h. In summary, this is the first study to show that the genus Brevibacillus may have strains that can degrade cellulose.

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Section: Introductionmentioning

confidence: 99%

Study of cellulases from a newly isolated thermophilic and cellulolytic Brevibacillus sp. strain JXL

Liang

Yesuf

Schmitt

et al. 2009

J Ind Microbiol Biotechnol

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“…The mechanisms and the effects of cellulase on cellulose fibers have been extensively reviewed. [9][10][11][12] Cellulase is a general term for a group of enzymes that hydrolyze the b-(1,4)-linkages in cellulose. Cellulase consists of three different enzymes that act synergistically in the hydrolysis of cellulose.…”

Section: Introductionmentioning

confidence: 99%

Surface and pore structure modification of cellulose fibers through cellulase treatment

Park

Venditti

Abrecht

et al. 2006

J of Applied Polymer Sci

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The surface and pore structure of cellulose fibers have a significant impact on the properties and performance in applications. Cellulase enzymatic hydrolysis of cellulose fibers can result in changes to the surface and pore structure, thus providing a useful tool for fiber modification. This research characterizes these changes using various test methods such as fiber dimension, water retention value (WRV), hard-to-remove (HR) water content, freezing and nonfreezing bound water content, polymer adsorption, and crystallinity index. For a high-dosage cellulase treatment (600 U/g dry solid), the fiber length was significantly decreased and the fibers were ''cut'' in the cross direction, not in the axial direction. The swelling capacities as measured by the WRV and HR water content increased for the high-dosage treatment. Three independent measurements (nonfreezing bound water, polymer adsorption, and crystallinity index) are in good agreement with the statement that the amorphous regions of cellulose fibers are a more readily available substrate relative to crystalline regions.

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“…However, the enzymatic hydrolysis reaction (most commonly with cellulases from the fungus Trichoderma reesei) is (still) too expensive (2.5-5 US cent per liter (10-20 US cents per gallon) of ethanol produced) and time-consuming (about 100-fold slower than the average fermentation rate with yeast) (Schubert, 2006;Gray et al, 2006). Many new enzymes from bacteria and fungi have been isolated and characterized in the last few years (Hildén & Johansson, 2004). Recently, the metagenome of the hindgut of the wood-feeding termite Nasutitermes has been analyzed with the aim to find novel cellulases (Warnecke et al, 2007).…”

Section: Cellulosic Biofuelsmentioning

confidence: 99%

The Past, Present, and Future of Biofuels – Biobutanol as Promising Alternative

Köpke¹,

Steffi²,

Dürre³

2011

Biofuel Production-Recent Developments and Prospects

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Recent developments on cellulases and carbohydrate-binding modules with cellulose affinity

Cited by 105 publications

References 101 publications

Study of cellulases from a newly isolated thermophilic and cellulolytic Brevibacillus sp. strain JXL

Study of cellulases from a newly isolated thermophilic and cellulolytic Brevibacillus sp. strain JXL

Surface and pore structure modification of cellulose fibers through cellulase treatment

The Past, Present, and Future of Biofuels – Biobutanol as Promising Alternative

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