cellulase and chlorite

Cellulose nanofibers (CNF) are renewable and biodegradable nanomaterials with attractive barrier, mechanical and surface properties. In this work, three different recombinant enzymes: an endoglucanase, a xylanase and a lytic polysaccharide monooxygenase, were combined to enhance cellulose fibrillation and to produce CNF from sugarcane bagasse (SCB). Prior to the enzymatic catalysis, SCB was chemically pretreated by sodium chlorite and KOH, while defibrillation was accomplished via sonication. We obtained much longer (μm scale length) and more thermostable (resisting up to 260 °C) CNFs as compared to the CNFs prepared by TEMPO-mediated oxidation. Our results showed that a cooperative action of the set of hydrolytic and oxidative enzymes can be used as a "green" treatment prior to the sonication step to produce nanofibrillated cellulose with advanced properties.

Topics: Biocatalysis; Biodegradation, Environmental; Cellulase; Cellulose; Chlorides; Cyclic N-Oxides; Endo-1,4-beta Xylanases; Green Chemistry Technology; Humans; Hydrolysis; Hydroxides; Mixed Function Oxygenases; Nanofibers; Oxidation-Reduction; Polysaccharides; Potassium Compounds; Saccharum; Sonication

In this work, a simplified and cost-effective chlorite pretreatment method to improve the hydrolysabiliy of biomass was developed. Compared to common used sodium chlorite-acetic acid (SCA) pretreatment (18.1%), sodium chlorite (SC) pretreatment resulted in less xylan loss (7.8%), thus led more carbohydrates retention. Moreover, the Chinese silvergrass pretreated by SC for 2 h achieved higher glucose yield (70.5%) than the substrate pretreated by SCA under the same pretreatment conditions did (58.7%), after 48 h enzymatic hydrolysis by cellulase. By synergistic action of cellulase and xylanase, the glucose yield of SC pretreated (12 h) samples reached to 93.5% with 808.7 mg/g DM total reducing sugars yields. In addition, without the usage of acetic acid could decrease the process cost and result in less inhibitor generation in pretreatment process.

Topics: Carbohydrate Metabolism; Carbohydrates; Cellulase; Chlorides; Hydrolysis; Poaceae

The multiple effects of pretreatments by chemical delignification using acidified sodium chlorite (ASC) and swelling using sodium bicarbonate (SB) for enzymatic saccharification of rice straw in bioethanol production have been investigated in this study. The treatment with the combination of ASC three times (3× ASC) first and SB later resulted in the significant reduction in Klason lignin content up to 90% (wt./wt.). By the saccharification of the pretreated rice straw with cellulase enzymes, it was confirmed that SB treatment was an important step in the pretreatment process not only to disintegrate the cellulose structure but also to facilitate the amorphization of the crystalline cellulose as well as the extended removal of integrated lignin. Furthermore, FTIR analyses revealed that the crystal type of cellulose appeared to be changed from type I to type II by SB treatment, thereby increasing the cellulose surface area and making it more accessible to the cellulase enzyme. Conversion rate to sugar was remarkably increased when 3× ASC + SB treatments were applied to untreated rice straw, even though the saccharification of the treated rice straw was performed at a low enzyme loading (1/100, wt.-enzymes/wt.-substrate). Conclusively, rice straw could be saccharified at high yield in short time at low cellulase loading, enables the enzymatic saccharification to be more feasible for practical bioethanol production using rice straw as a substrate.

Topics: Biofuels; Carbohydrates; Cellulase; Cellulose; Cellulose 1,4-beta-Cellobiosidase; Chlorides; Ethanol; Lignin; Oryza; Sodium Bicarbonate

Cellulases which are active and stable under extreme conditions have attracted considerable attention because of their potential industrial applications. Marinimicrobium sp. LS-A18 showed high extracellular carboxymethylcellulase (CMCase) activity when grown on mineral salt medium containing carboxymethylcellulose as the sole carbon source. Maximum CMCase activity was obtained at 55°C and pH 7.0 in the absence of NaCl. Under the optimized fermentation conditions, the yield of CMCase was increased up to 2.5 U/ml, which was 3.1-fold higher than that before optimization. The enzyme retained 84 % of residual activity after incubation at 60°C for 1 h and more than 88 % of residual activity after incubation for 72 h in the presence of different pH (5-11) and NaCl concentrations (0-25 %, w/v), indicating it was halotolerant, thermostable and alkali-stable. These characteristics made the CMCase from Marinimicrobium sp. LS-A18 as a potentially novel biocatalyst in biotechnological and industrial applications.

Topics: Alkalies; Alteromonadaceae; Bacterial Proteins; Cellulase; Chlorides; Enzyme Stability; Extracellular Space; Kinetics; Seawater; Temperature

The effect of delignification methods on enzymatic hydrolysis of forest biomass was investigated using softwood and hardwood that were pretreated at an alkaline condition followed by sodium chlorite or ozone delignification. Both delignifications improved enzymatic hydrolysis especially for softwood, while pretreatment alone was found effective for hardwood. High enzymatic conversion was achieved by sodium chlorite delignification when the lignin content was reduced to 15%, which is corresponding to 0.30-0.35 g/g accessible pore volume, and further delignification showed a marginal effect. Sample crystallinity index increased with lignin removal, but it did not show a correlation with the overall carbohydrate conversion of enzymatic hydrolysis.

Topics: beta-Glucosidase; Biomass; Cellulase; Chlorides; Chromatography, High Pressure Liquid; Endo-1,4-beta Xylanases; Hydrolysis; Lignin; Ozone; Trees; Wood

1. Polymers were solubilized from the cell walls of parenchyma from mature runner-bean pods with minimum degradation by successive extractions with cyclohexane-trans-1,2-diamine-NNN'N'-tetra-acetate (CDTA), Na2CO3 and KOH to leave the alpha-cellulose residue, which contained cross-linked pectic polysaccharides and Hyp-rich glycoproteins. These were solubilized with chlorite/acetic acid and cellulase. The polymers were fractionated by anion-exchange chromatography, and fractions were subjected to methylation analysis. 2. The pectic polysaccharides differed in their ease of extraction, and a small proportion were highly cross-linked. The bulk of the pectic polysaccharides solubilized by CDTA and Na2CO3 were less branched than those solubilized by KOH. There was good evidence that most of the pectic polysaccharides were not degraded during extraction. 3. The protein-containing fractions included Hyp-rich and Hyp-poor glycoproteins associated with easily extractable pectic polysaccharides, Hyp-rich glycoproteins solubilized with 4M-KOH+borate, the bulk of which were not associated with pectic polysaccharides, and highly cross-linked Hyp-rich glycoproteins. 4. Isodityrosine was not detected, suggesting that it does not have a (major) cross-linking role in these walls. Instead, it is suggested that phenolics, presumably linked to C-5 of 3,5-linked Araf residues of Hyp-rich glycoproteins, serve to cross-link some of the polymers. 5. There were two main types of xyloglucan, with different degrees of branching. The bulk of the less branched xyloglucans were solubilized by more-concentrated alkali. The anomeric configurations of the sugars in one of the highly branched xyloglucans were determined by 13C-n.m.r. spectroscopy. 6. The structural features of the cell-wall polymers and complexes are discussed in relation to the structure of the cell walls of parenchyma tissues.

Topics: Acetates; Acetic Acid; Amino Acids; Bicarbonates; Carbohydrate Conformation; Cell Wall; Cellulase; Chlorides; Chromatography, Ion Exchange; Edetic Acid; Fabaceae; Glycoproteins; Glycosides; Hydroxides; Magnetic Resonance Spectroscopy; Methylation; Plants; Plants, Medicinal; Polymers; Polysaccharides; Potassium; Potassium Compounds; Sodium; Sodium Bicarbonate; Solubility; Tyrosine