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PubMed2003

CelF of Orpinomyces PC-2 has an intron and encodes a cellulase (CelF) containing a carbohydrate-binding module.

A cDNA, designated celF, encoding a cellulase (CelF) was isolated from the anaerobic fungus Orpinomyces PC-2. The open reading frame contains regions coding for a signal peptide, a carbohydrate-binding module (CBM), a linker, and a catalytic domain. The catalytic domain was homologous to those of CelA and CelC of the same fungus and to that of the Neocallimastix patriciarum CELA, but CelF lacks a docking domain, characteristic for enzymes of cellulosomes. It was also homologous to the cellobiohydrolase IIs and endoglucanases of aerobic organisms. The gene has a 111-bp intron, located within the CBM-coding region. Some biochemical properties of the purified recombinant enzyme are described.

Base Sequence↗
PubMedDate not supplied

Differential thermal and thermogravimetric analyses of bound water content in cellulosic substrates and its significance during cellulose hydrolysis by alkaline active fungal cellulases.

Various cellulosic substrates were examined for bound water content by differential thermal analysis (DTA) and thermogravimetry (TG). Samples were heated in the range of 30-100 degrees C at a rate of 3 degrees C/min. DTA vaporization curves for different cellulose samples indicated that the bound water (Wf) was vaporized at higher temperature than free water (Wf) at the surface. Weight loss was observed in two stages, corresponding to Wf and Wb in TG curves. The bound water content was dependent on the degree of crystallinity of cellulose. Among different cellulosic substrates, Walseth cellulose showed the highest bound water content, and it also was found to be the least crystalline. The alkaline-active, alkali-stable cellulase was obtained from the alkalotolerant Fusarium sp. The substrate specificity and viscometric characteristics confirmed the enzyme to be an endoglucanase. The Wb content of Walseth cellulose was lowered during the enzymatic hydrolysis. The possible application of bound water analysis in understanding the hydrolysis of cellulosic substrates of different crystallinity is discussed.

Cellulases↗
PubMed2005

Enzymatic hydrolysis of steam-exploded and ethanol organosolv-pretreated Douglas-Firby novel and commercial fungal cellulases.

Softwood residues are the most abundant feedstock available for bioconversion in many northern countries. However, the high costs for delignification and enzymatic hydrolysis currently deter commercialization of softwood bioconversion processes. This study evaluates the abilities of two novel fungal preparations (MSUBC1 and MSUBC2) and two commercial cellulase preparations (TR1 and TR2) to hydrolyze cellulose in Douglas-firpretreated by steam explosion or ethanol organosolv process. MSUBC1 showed significantly better performance than the other preparations on both lignocellulosic substrates. In particular, MSUBC1 achieved >76% cellulose conversion for hydrolysis of steam-exploded Douglas-fir (approximately 44% lignin) after 72 h at low enzyme loading (10 filter paper units/g of cellulose) and without beta-glucosidase supplementation.

Biodegradation, Environmental↗
PubMed2006

Gene transfer between different Trichoderma species and Aspergillus niger through intergeneric protoplast fusion to convert ground rice straw to citric acid and cellulases.

Single-stage direct bioconversion of cellulosic materials to citric acid using intergeneric hybrids obtained from three different Trichoderma species and Aspergillus niger was carried out. The recent results were obtained on the basis of either resistance or sensitivity to one or more of five metal ions, two catabolite repressors, and five antifungal agents, which were used in this study at different concentrations. Sixty-six fusants were isolated after using the three intergeneric protoplast fusion experiments, belonging to two types of intergeneric fusants. Fusants of the first type are heterokaryons (35 fusants). On the other hand, those of the second type are haploids (31 fusants), i.e., they were stable. The present study can be successfully applied in the construction of 14 new genetic fusants, which produced at least 100% more citric acid than the citric acid producer strain A. niger. Out of the fusants, three (1/18, 2/13 and 2/15) showed about a threefold increase of citric acid production in comparison with the parent A. niger strain. Furthermore, studies on DNA content showed that this finding may be submitted on the evidence that citric acid and cellulases production was not correlated with DNA content; however, the productivity depends on specific DNA content.

Antifungal Agents↗
PubMedDate not supplied

Semi-solid-state fermentation of Eicchornia crassipes biomass as lignocellulosic biopolymer for cellulase and 3-glucosidase production by cocultivation of Aspergillus niger RK3 and Trichoderma reesei MTCC164.

An aquatic weed biomass, Eicchornia crassipes, present in abundance and leading to a threatening level of water pollution was used as substrate for cellulase and beta-glucosidase production using wild-type strain Aspergillus niger RK3 that was isolated from decomposing substrate. Alkali treatment of the biomass (10%) resulted in a 60-66% increase in endoglucanase, exoglucanase, and beta-glucosidase production by the A. niger RK3 strain in semi-solid-state fermentation. Similarly, the alkali-treated biomass led to a 45-54% increase in endo- and exoglucanase and a higher (98%) increase in beta-glucosidase production by Trichoderma reesei MTCC164 under similar conditions. However, the cocultivation of A. niger RK3 and T. reesei MTCC164 at a ratio of 3:1 showed a 20-24% increase in endo- and exoglucanase activities and about a 13% increase in the beta-glucosidase activity over the maximum enzymatic activities observed under single culture conditions. Multistep physical (ultraviolet) and chemical (N-methyl-N'-nitrosoguanidine, sodium azide, colchicine) mutagenesis of the A. niger RK3 strain resulted in a highly cellulolytic mutant, UNSC-442, having an increase of 136, 138, and 96% in endoglucanase, exoglucanase, and beta-glucosidase, activity, respectively. The cocultivation of mutant UNSC-442 along with T. reesei MTCC164 (at a ratio of 3:1) showed a further 10-11% increase in endo- and exoglucanase activities and a 29% increase in beta-glucosidase activity in semi-solid-state fermentation.

Aspergillus niger↗
PubMed1995

Filament-specific expression of a cellulase gene in the dimorphic fungus Ustilago maydis.

The phytopathogenic fungus Ustilago maydis exists in a yeast-like haploid form and as a filamentous dikaryon. Only the dikaryon can infect corn plants. We have isolated a gene, egl1, that is not expressed in haploid cells but strongly induced in the filament. Molecular and biochemical analyses revealed that egl1 encodes a cellulase. By immunogold labelling, secreted protein could be detected at the hyphal tip. Mutants deleted for egl1 are viable and are affected neither in filament formation nor in pathogenic development under the conditions tested.

Amino Acid Sequence↗
PubMed1984

Influence of dietary fiber on the performance and cellulase activity of growing-finishing swine.

Number of cellulolytic bacteria and their cellulase activity were determined from fecal samples of eight pairs of littermate pigs representing four litters (26 to 32 kg) fed a low or high fiber diet ad libitum (0 or 35% alfalfa meal, respectively) over a 70-d period. Fecal samples were obtained from all pigs on d 0, 5, 11, 18, 32, 53 and a final sample between d 67 to 70. Cecum and colon samples were obtained at slaughter. Growth and carcass data were also obtained during the study. Pigs fed the high fiber diet gained 17.3% less, had increased feed to gain ratio and less carcass weight at slaughter than those fed the low fiber diet (P less than .05). Overall, a larger number of cellulolytic bacteria (P less than .05) were found in the fecal samples from pigs fed the high fiber diet. The overall mean cellulolytic activity (mg glucose released X g dry weight fecal sample-1 X 30 min-1) was 27.7 compared with 33.8 (P less than .05) for the pigs fed the low and high fiber diet, respectively. A lower concentration of organic acids (P less than .05) was present in the fecal samples of the high fiber pigs. The overall mean acetate to propionate ratio was 1.92 and 2.48 (P less than .01), and ammonia-N was 2.27 and .98 mg/g dry weight (P less than .01) for the low and high fiber diet pigs, respectively. These data indicated that a 35% alfalfa meal diet significantly affects intestinal bacterial metabolism and number and activity of the cellulolytic population, along with performance and carcass characteristics.

Animals↗
PubMed1978

A conjugate of cellulase with fluorescein isothiocyanate: a specific stain for cellulose.

A fluorescent technique has been developed for in situ staining of cellulose. The staining agent in conjugate of cellulase and fluorescein isothiocyanate (FITC). Application of this agent does not disturb intercellular or intracellular substances. The technique depends on the specific binding of the fluorescent labeled enzyme to its substrate. The stain has been tested on cell-free noncellulose polysaccharides similar to cellulose and does not stain them. The technique has been used to localize cellulose during the life cycle of Dictyostelium discoideum with results that correspond to previous work using other methods.

Acetobacter↗
PubMed2000

Determination of when during the lactation cycle to start feeding a cellulase and xylanase enzyme mixture to dairy cows.

We used 48 multiparous Holstein cows to compare the response of dairy cows to a direct-fed mixture of cellulase and xylanase enzymes (1.25 L of enzyme concentrate/tonne of forage dry matter) applied to the forage portion (60% corn silage and 40% alfalfa hay) of a total mixed diet starting either in the close-up dry period, at calving, or at peak milk production. Cows were blocked by calving date and, within blocks, randomly assigned to one of four treatment diets. Treatments were: 1) an untreated control diet, 2) enzyme addition to the forage from wk 6 to 18 postpartum, 3) enzyme addition to the forage from calving to wk 18 postpartum, and 4) enzyme addition to the forage from wk 4 prepartum to wk 18 postpartum. Total mixed diets were 65% forage and 35% concentrate prepartum, and 50:50 forage:concentrate postpartum. The production of milk, solids-corrected milk, fat-corrected milk, and energy-corrected milk was higher for cows fed enzyme-treated diets than for cows fed control diet. Production was similar for cows in all enzyme-treated groups, although numerically highest for cows that started receiving enzyme-treated forages right after parturition and numerically lowest when started prepartum. Concentrations of fat, protein, and lactose in milk were similar for all treatments; yields of protein and fat were higher for cows fed enzyme-treated forages. Dry matter intake and body condition scores, both prepartum and postpartum, were similar for all diets. Eating rates, as determined in two 24-h studies, were similar for control and enzyme-treated diets. The feeding of enzyme-treated forages increased milk production. While the effect of when the feeding of enzyme-treated forages started was not statistically significant, we recommend starting soon after parturition because of the greatest total milk production when starting at that time.

Animal Feed↗
PubMed1999

Response of lactating dairy cows to a cellulase and xylanase enzyme mixture applied to forages at the time of feeding.

Fifty Holstein cows (20 primiparous and 30 multiparous) were used in an experiment to evaluate the dose response to a direct-fed cellulase and xylanase enzyme mixture applied to the forage portion (60% corn silage and 40% alfalfa hay) of a total mixed ration just prior to feeding. Cows were fed one of five treatment diets for 12 wk. Diets 1 through 4 were 55% forage: 45% concentrate and consisted of an untreated control and the control diet plus 0.7, 1.0, or 1.5 L of enzyme concentrate/tonne of forage dry matter, respectively. Diet 5 was an untreated 45% forage: 55% concentrate diet. Actual production of milk increased as much as 10.8% relative to the control diet with 1.5 L of enzyme, and production of fat and protein increased as much as 20 and 13%, respectively. The lowest concentration of enzyme treatment (0.7 L/tonne) accounted for approximately one-half of the production increases. The responses to enzyme-treated forages occurred 2 to 4 wk after the cows started to consume the treated forages, and the same responses were maintained throughout the remainder of the experiment. Cows that started to receive enzyme-treated forage during the first 100 d postpartum produced 9 to 15% more milk and 16 to 23% more energy-corrected milk than did cows fed the control diet. However, production was not increased when cows were in midlactation at the start of the experiment. Responses to enzyme-treated forages fed in 55: 45 forage to concentrate rations were similar to the response to increased proportions of concentrates fed with untreated forages at the 45:55 forage to concentrate ratio.

Animal Feed↗
PubMed2000

Antibacterial activity of a chitooligosaccharide mixture prepared by cellulase digestion of shrimp chitosan and its application to milk preservation.

The antibacterial activity of a chitooligosaccharide mixture prepared by digestion of shrimp chitosan with cellulase at 50 degrees C for 14 h was evaluated. Sugars with 1 to 8 degrees of polymer (DP) were found in this chitooligosaccharide mixture, and the weight percentage of sugars with DP > or = 6 was 44.3%. Minimal lethal concentrations of this mixture against Aeromonas hydrophila, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, Shigella dysenteriae, Staphylococcus aureus, Vibrio cholerae, and Vibrio parahaemolyticus in nutrient broth were 5 to 29 ppm, which were much lower than those of the chitosan reactant (50 to 1,000 ppm). The antibacterial activity of this mixture in the sterilized milk against E. coli O157, L. monocytogenes, Salmonella Typhimurium, and S. aureus was much stronger at 4 degrees C than at 37 degrees C. When raw milk was supplemented with either 0.24% or 0.48% (wt/vol) of this oligosaccharide mixture and stored at 4 degrees C for 12 days, its mesophilic and psychrotrophic counts were reduced by at least 3 log cycles, and there was very little change in pH. In addition, this mixture retarded the growth of Salmonella species and caused quicker reduction of Staphylococcus species in raw milk. Accordingly, the shelf life of raw milk at 4 degrees C was extended by at least 4 days.

Aeromonas hydrophila↗
PubMed2004

Antimicrobial activity of a low-molecular-weight chitosan obtained from cellulase digestion of chitosan.

A water-soluble chitosan hydrolysate with high activity against Escherichia coli was obtained during cellulase digestion of chitosan for 18 h. This 18-h hydrolysate is composed of low-molecular-weight chitosan (LMWC), with a molecular weight of 12.0 kDa, and chitooligosaccharides, which are composed of sugars with a degree of polymerization of 1 to 8. LMWC has a strong activity at 100 ppm against many pathogens and yeast species, including Bacillus cereus, E. coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica serovar Typhi, and Saccharomyces cerevisiae, while the chitooligosaccharides have much weaker antimicrobial activity than does LMWC. Accordingly, the antimicrobial activity against E. coli in the 18-h hydrolysate proved to come mainly from the presence of LMWC.

Anti-Bacterial Agents↗
PubMed1999

Cellulase complex from Chaetomium cellulolyticum: isolation and properties of major components.

Four major components of the cellulase complex of Chaetomium cellulolyticum have been isolated by gel-filtration, ion-exchange chromatography on DEAE-Toyopearl and Macro Prep Q, and chromatofocusing on Mono P. These components include three endoglucanases (19, 35, and 40 kD) and a cellobiohydrolase (45 kD). The isoelectric points of the enzymes vary from 3.8 to 4.2. The optimal pH values for catalytic activity are in the range 4.5-6.0, and the optimal temperatures are in the range 60-70 degrees C. Of these enzymes the 19 kD endoglucanase is the most stable; it retained high activity within a broad pH range (from 5.0 to 9.6) at 50 degrees C for 3 h. This enzyme also had the highest topolytic activity determined by the efficiency of removal of indigo from the surface of cotton.

Cellulase↗
PubMed2000

Structure and function of Humicola insolens family 6 cellulases: structure of the endoglucanase, Cel6B, at 1.6 A resolution.

Cellulases are traditionally classified as either endoglucanases or cellobiohydrolases on the basis of their respective catalytic activities on crystalline cellulose, which is generally hydrolysed more efficiently only by the cellobiohydrolases. On the basis of the Trichoderma reesei cellobiohydrolase II structure, it was proposed that the active-site tunnel of cellobiohydrolases permitted the processive hydrolysis of cellulose, whereas the corresponding endoglucanases would display open active-site clefts [Rouvinen, Bergfors, Teeri, Knowles and Jones (1990) Science 249, 380-386]. Glycoside hydrolase family 6 contains both cellobiohydrolases and endoglucanases. The structure of the catalytic core of the family 6 endoglucanase Cel6B from Humicola insolens has been solved by molecular replacement with the known T. reesei cellobiohydrolase II as the search model. Strangely, at the sequence level, this enzyme exhibits the highest sequence similarity to family 6 cellobiohydrolases and displays just one of the loop deletions traditionally associated with endoglucanases in this family. However, this enzyme shows no activity on crystalline substrates but a high activity on soluble substrates, which is typical of an endoglucanase. The three-dimensional structure reveals that the deletion of just a single loop of the active site, coupled with the resultant conformational change in a second 'cellobiohydrolase-specific' loop, peels open the active-site tunnel to reveal a substrate-binding groove.

Amino Acid Sequence↗
PubMed2000

Electrochemical assay of endo-depolymerase activity of cellulases.

A method for determination of endo-1,4-beta-D-glucanase activity of cellulase samples based on the indirect measurement of decrease in viscosity of a carboxymethylcellulose solution in an electrochemical cell in the presence of an electron carrier was developed. A rotating disk electrode is used as the working electrode. When two reactions (enzymatic and electrochemical) proceeded in the cell simultaneously, the limiting diffusion current at a constant applied potential increases as the viscosity of the solution decreases. Conditions where the initial rate of change of diffusion current (dI/dt) is proportional to the enzyme concentration were found. A good correlation between the new method and a previously known viscometric method for determination of endoglucanase activity was observed.

Carboxymethylcellulose Sodium↗
PubMed1999

[The reactions in ginseng cells induced by elicitor derived from digesting ginseng cell walls by cellulase].

After treatment of the elicitor derived from digesting ginseng cell walls by cellulase, the starch grains were degraded, and a large number of spherosomes were produced in Ginseng cells. In the mean time, the activity of amylase in the cells was increased and the activities of esterases in the cells were reduced; in addition, the content of soluble sugar and the content of lipoid were increased. These indicate that the emergency reactions and the adjustment of metabolism of lipoid were taken placed in the cells elicited. Besides, after the treatment with certain concentrations of elicitor, the content of ginseng saponin and the activity of phenylalanine ammonia lyase (PAL) were increased in ginseng cells. On the contrary, the activities of peroxidase (POD) and polyphenoloxidase (PPO) were reduced.

Amylases↗