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21.
Melanocarpus albomyces, a thermophilic fungus isolated from compost by enrichment culture in a liquid medium containing sugarcane bagasse, produced
cellulase-free xylanase in culture medium. The fungus was unusual in that xylanase activity was inducible not only by hemicellulosic
material but also by the monomeric pentosan unit of xylan but not by glucose. Concentration of bagasse-grown culture filtrate
protein followed by size-exclusion and anion-exchange chromatography separated four xylanase activities. Under identical conditions
of protein purification, xylanase I was absent in the xylose-grown culture filtrate. Two xylanase activities, a minor xylanase
IA and a major xylanase IIIA, were purified to apparent homogeneity from bagasse-grown cultures. Both xylanases were specific
forβ-1,4 xylose-rich polymer, optimally active, respectively, at pH 6.6 and 5.6, and at 65°C. The xylanases were stable between
pH 5 to 10 at 50°C for 24 h. Xylanases released xylobiose, xylotriose and higher oligomers from xylans from different sources.
Xylanase IA had a Mr of 38 kDa and contained 7% carbohydrate whereas xylanase IIIA had a Mr of 24 kDa and no detectable carbohydrate. The Km for larchwood xylan (mg ml−1) and Vmax (μmol xylose min−1 mg−1 protein) of xylanase IA were 0.33 and 311, and of xylanase IIIA 1.69 and 500, respectively. Xylanases IA, II and IIIA showed
no synergism in the hydrolysis of larchwood glucuronoxylan or oat spelt and sugarcane bagasse arabinoxylans. They had different
reactivity on untreated and delignified bagasse. The xylanases were more reactive than cellulase on delignified bagasse. Simultaneous
treatment of delignified bagasse by xylanase and cellulase released more sugar than individual enzyme treatments. By contrast,
the primary cell walls of a plant, particularly from the region of elongation, were more susceptible to the action of cellulase
than xylanase. The effects of xylanase and cellulase on plant cell walls were consistent with the view that hemicellulose
surrounds cellulose in plant cell walls. 相似文献
22.
23.
R.R.M. Zautsen F. Maugeri‐Filho C.E. Vaz‐Rossell A.J.J. Straathof L.A.M. van der Wielen J.A.M. de Bont 《Biotechnology and bioengineering》2009,102(5):1354-1360
Several compounds that are formed or released during hydrolysis of lignocellulosic biomass inhibit the fermentation of the hydrolysate. The use of a liquid extractive agent is suggested as a method for removal of these fermentation inhibitors. The method can be applied before or during the fermentation. For a series of alkanes and alcohols, partition coefficients were measured at low concentrations of the inhibiting compounds furfural, hydroxymethyl furfural, vanillin, syringaldehyde, coniferyl aldehyde, acetic acid, as well as for ethanol as the fermentation product. Carbon dioxide production was measured during fermentation in the presence of each organic solvent to indicate its biocompatibility. The feasibility of extractive fermentation of hydrolysate was investigated by ethanolic glucose fermentation in synthetic medium containing several concentrations of furfural and vanillin and in the presence of decanol, oleyl alcohol and oleic acid. Volumetric ethanol productivity with 6 g/L vanillin in the medium increased twofold with 30% volume oleyl alcohol. Decanol showed interesting extractive properties for most fermentation inhibiting compounds, but it is not suitable for in situ application due to its poor biocompatibility. Biotechnol. Bioeng. 2009;102: 1354–1360. © 2008 Wiley Periodicals, Inc. 相似文献
24.
S. Prakash Y. Veeranagouda L. Kyoung K. Sreeramulu 《World journal of microbiology & biotechnology》2009,25(2):197-204
A halophilic and alkali-tolerant Chromohalobacter sp. TPSV 101 with an ability to produce extracellular halophilic, alkali-tolerant and moderately thermostable xylanase was
isolated from solar salterns. Identification of the bacterium was done based upon biochemical tests and 16S rRNA sequence.
The culture conditions for higher xylanase production were optimized with respect to NaCl, pH, temperature, substrates and
metal ions and additives. Maximum xylanase production was achieved in the medium with 20% NaCl, pH-9.0 at 40°C supplemented
with 1% (w/v) sugarcane bagasse and 0.5% feather hydrolysate as carbon and nitrogen sources. Sugarcane bagasse (250 U/ml)
and wheat bran (190 U/ml) were the best inducer of xylanase when used as carbon source as compared to xylan (61 U/ml). The
xylanase that was partially purified by protein concentrator had a molecular mass of 15 kDa approximately. The xylanase from
Chromohalobacter sp. TPSV 101 was active at pH 9.0 and required 20% NaCl for optimal xylanolytic activity and was active over a broad range
of temperature 40–80°C with 65°C as optimum. The early stage hydrolysis products of sugarcane bagasse were xylose and xylobiose,
after longer periods of incubation only xylose was detected. 相似文献
25.
A complete cellulase from Penicillium pinophilum was evaluated for the hydrolysis of α-cellulose derived from steam exploded sugarcane bagasse and other cellulosic substrates. α-Cellulose at 1% substrate concentration was completely hydrolyzed by Penicillium cellulase within 3 h wherein at 10% the hydrolysis was 100% within 24 h with an enzyme loading of 10 FPU/g. The hydrolysate yielded glucose as major end product as analyzed by HPLC. Under similar conditions, hydrolysis of Sigmacell (microcrystalline cellulose), CP-123 (pulverized cellulose powder) and ball milled Solka Floc were 42%, 56% and 52%, respectively. Further the hydrolysis performance of Penicillium sp. cellulase is compared with Trichoderma reesei cellulase (AccelleraseTM 1000) from Genencore. The kinetics of hydrolysis with respect to enzyme and substrate concentration will be presented. 相似文献
26.
To promote the decomposition of sugarcane bagasse (SCB) for conversion into value-added products and to reduce waste, the capability of fungal mixes (FMs) to degrade SCB was examined. A total of 169 isolates from SCB and non-SCB were categorized as thermotolerant and thermoresistant. Thirty-six fungal candidates were screened for the presence of polyphenol oxidase, endoglucanase (EDN) and xylanase (XLN) activities, and EDN and XLN activities were quantitated. Five identified isolates (Aspergillus flavus AG10; Aspergillus niger AG68 & NB23; and Penicillium citrinum AG93 & AG140) were selected as the best enzyme producers, and 15 moderately to highly xylolytic, cellulolytic and ligninolytic isolates were added to construct FMs. Using a Taguchi design, the top ten reducing sugar-producing FMs (no. 12 showed the maximum amount of reducing sugar, at 2.11 mg g−1, followed by no. 7, 15, 2, 16, 11, 13, 6, 4, & 8) were selected as potential agents for decomposition durations of 1, 2 and 3 months. The maximum decrease in SCB materials compared with the control was generated by FM 6 (9.08% cellulose reduction); FM 13 (21.03% hemicellulose reduction); and FM 16 (9.21% lignin reduction). These results indicate the potential use of SCB as a substrate for synergistic FMs. These FMs could be applied to the large-scale composting of SCB and other related agricultural residues, thus improving the biological pretreatment of lignocellulose. 相似文献
27.
Hydrothermal processing and enzymatic hydrolysis of sorghum bagasse for fermentable carbohydrates production 总被引:1,自引:0,他引:1
Ioannis Dogaris Sofia Karapati Diomi Mamma Emmanuel Kalogeris Dimitris Kekos 《Bioresource technology》2009,100(24):6543-6549
Untreated and hydrothermally treated sorghum bagasse (SB) was hydrolyzed to simple sugars by the synergistic action of cellulases and hemicellulases produced by the fungi Fusarium oxysporum and Neurospora crassa. Synergism between the two lignocellulolytic systems was maximized with the application of higher fraction of N. crassa enzymes.Hydrothermolysis of SB was studied at a wide range of treatment times and temperatures. At intense pretreatment conditions (210 °C for 20 min; logR0 = 4.54), the residual hemicellulose percentage was 17.45%, while formation of inhibitory products, 5-hydromethyl-furfural (HMF), furfural, acetic and formic acid, (0.21, 0.51, 3.36 and 1.80 g/l, respectively) remained in acceptable levels.Maximum conversion of cellulose and total polysaccharides of the untreated SB were 23.18% and 18.79%, respectively. Combining hydrothermal treatment and enzymatic hydrolysis of released oligosaccharides and insoluble solids resulted in improvement of cellulose (approximately 15% increase) and total polysaccharides (two fold) hydrolysis compared to that of untreated SB. 相似文献
28.
Giselle Torres-Farradá Ana M. Manzano Miguel Ramos-Leal Osmel Domínguez María Isabel Sánchez Jaco Vangronsveld 《Bioremediation Journal》2018,22(1-2):25-32
White-rot fungi are considered to be promising biotechnological tools to complement or replace the current technologies for the treatment of effluents from textile production plants. The aim of this work was to investigate the decolorization capacity of Ganoderma weberianum B-18 in solid state fermentation with sugarcane bagasse as a substrate and ligninolytic inducer as well as to decolorize and detoxify industrial effluents by this strain in a laboratory scale packed-bed bio-reactor. The results demonstrated that G. weberianum B-18 indeed showed to possess decolorization capacity in solid state fermentation with sugarcane bagasse supplemented with synthetic dyes. Moreover, fungal biomass of G. weberianum B-18 immobilized in sugarcane bagasse in a packed-bed bioreactor was shown to efficiently decolorize and detoxify different dyes and authentic industrial effluents in semi-continuous conditions. In this decolorization process, laccase enzymes secreted by the fungus played the main role. Hence, a packed-bed reactor with G. weberianum B-18 immobilized in sugarcane bagasse seems to be a suitable system for the further development of an efficient bioprocess for large-scale treatment of dye-containing wastewaters. 相似文献
29.
30.
M G A Felipe M Vitolo I M Mancilha S S Silva 《Journal of industrial microbiology & biotechnology》1997,18(4):251-254
The bioconversion of xylose to xylitol by Candida guilliermondii FTI 20037 cultivated in sugar cane bagasse hemicellulosic hydrolyzate was influenced by cell inoculum level, age of inoculum
and hydrolyzate concentration. The maximum xylitol productivity (0.75 g L−1 h−1) occurred in tests carried out with hydrolyzate containing 54.5 g L−1 of xylose, using 3.0 g L−1 of a 24-h-old inoculum. Xylitol productivity and cell concentration decreased with hydrolyzate containing 74.2 g L−1 of xylose.
Received 02 February 1996/ Accepted in revised form 15 November 1996 相似文献