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1.
Danny E. Akin W. Herbert Morrison III Luanne L. Rigsby Franklin E. Barton II David S. Himmelsbach Kevin B. Hicks 《Applied biochemistry and biotechnology》2006,129(1-3):104-116
Information is presented on structure, composition, and response to enzymes of corn stover related to barriers for bioconversion
to ethanol. Aromatic compounds occurred in most tissue cell walls. Ferulic acid esterase treatment before cellulase treatment
significantly improved dry weight loss and release of phenolic acids and sugars in most fractions over cellulase alone. Leaf
fractions were considerably higher in dry weight loss and released sugars with esterase treatment, but stem pith cells gave
up the most phenolic acids. Results help identify plant fractions more appropriate for coproducts and bioconversion and those
more suitable as residues for soil erosion control. 相似文献
2.
Leda M. F. Gottschalk Ronaldo Nobrega Elba P. S. Bon 《Applied biochemistry and biotechnology》2003,108(1-3):799-807
The effect of aeration on lignin peroxidase production by Streptomyces viridosporus T7A was studied in a bench-scale bioreactor using a previously optimized growth medium (0.65% yeast extract and 0.1% corn
oil, pH7.0) at 37°C and natural pH. Airflow rates of 0.3, 1.0, and 1.5 vvm and a fixed agitation of 200 rpm were initially
studied followed by 1.0 vvm and 200, 300, 400, and 500 rpm. The use of 1.0 vvm and 400 rpm increased enzyme concentration
1.8-fold (100–180 U/L) and process productivity 4.8-fold (1.4–6.7 U/[L·h]) in comparison with the use of 200 rpm and 0.3 vvm.
The inexpensive corn oil, used as carbon source, besides its antifoam properties, proved to be nonrepressive for enzyme production. 相似文献
3.
Catalytic nitrobenzene oxidation of lignins 总被引:1,自引:0,他引:1
A. F. Gogotov N. A. Rybal'chenko T. I. Makovskaya V. A. Babkin 《Russian Chemical Bulletin》1996,45(12):2854-2857
Alkaline nitrobenzene oxidation of hardwood and softwood lignins in the presence of redox and phase-transfer catalysts was studied. The selectivity of oxidation of lignins increased by 1.7 to 1.9 times. A possible mechanism of catalysis is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 3004–3007, December, 1996. 相似文献
4.
Raquel F. P. Nogueira Ronaldo A. Pilli Nelson durÁn 《Applied biochemistry and biotechnology》1992,33(3):169-176
Growth of the ascomyceteChrysonilia sitophila during degradation of lignin model dimers and monomers was compared to a glucose control. An inhibition of growth by Cα-carbonyl
monomers and stimulation by β-O-4 lignin model and vanillyl alcohol were observed. A comparison of the degradation by this
ascomycete with the basidiomycetePhanerochaete chrysosoporium showed similarities in relation to the type of degradation caused. 相似文献
5.
Aspen wood substrates with varying degrees of deacetylation, xylan, and lignin removal have been prepared and submitted to
enzymatic hydrolysis with a cellulase/hemicellulase preparation for an extended constant period of hydrolysis. Controlled
deacetylation has been achieved by treating wood with various alkali metal hydroxide solutions, at various alkali/wood ratios.
It has been found that samples with the same extent of deacetylation produce the same sugar yields upon enzymatic hydrolysis.
Increased degree of deacetylation increases the yield of sugars obtained from enzymatic hydrolysis, all other compositional
parameters held constant. The acetyl group removal is proportional to the stoichiometric relation between added base and wood
acetyl content, i.e., the same number of milliequivalents of base/weight of wood remove the same extent of acetyl groups,
regardless of the concentration of the base solution. No cation effects are found among Li, Na, and K alkali hydroxide solutions,
suggesting that swelling is not as important a parameter as is the removal of the acetyl groups from the xylan backbone in
determining the extent of hydrolyzability of the resulting sample. 相似文献
6.
Xuejun Pan Dan Xie Neil Gilkes David J. Gregg Jack N. Saddler 《Applied biochemistry and biotechnology》2005,124(1-3):1069-1079
Pretreatment of Douglas-fir by steam explosion produces a substrate containing approx 43% lignin. Two strategies were investigated
for reducing the effect of this residual lignin on enzymatic hydrolysis of cellulose: mild alkali extraction and protein addition.
Extraction with cold 1% NaOH reduced the lignin content by only approx 7%, but cellulose to glucose conversion was enhanced
by about 30%. Before alkali extraction, addition of exogenous protein resulted in a significant improvement in cellulose hydrolysis,
but this protein effect was substantially diminished after alkali treatment. Lignin appears to reduce cellulose hydrolysis
by two distinct mechanisms: by forming a physical barrier that prevents enzyme access and by non-productively binding cellulolytic
enzymes. Cold alkali appears to selectively remove a fraction of lignin from steam-exploded Douglas-fir with high affinity
for protein. Corresponding data for mixed softwood pretreated by organosolv extraction indicates that the relative importance
of the two mechanisms by which residual lignin affects hydrolysis is different according to the pre- and post-treatment method
used. 相似文献
7.
A large amount of inedible plant material, generated as a result of plant growth in a Controlled Ecological Life Support System
(CELSS), should be pretreated and converted into forms that can be recycled on earth as well as in space. The main portion
of the inedible biomass is lignocellulosic material. Enzymatic hydrolysis of this cellulose would provide sugars for many
other uses by recycling carbon, hydrogen, oxygen, and nitrogen through formation of carbon dioxide, heat, and sugars, which
are potential foodstuffs. To obtain monosaccharides from cellulose, the protective effect of lignin should be removed. White-rot
fungi degrade lignin more extensively and rapidly than other microorganisms.Pleurotus ostreatus degrades lignin effectively, and produces edible and flavorful mushrooms that increase the quality and nutritional value
of the diet. This mushroom is also capable of metabolizing hemicellulose, thereby providing a food use of this pentose containing
polysaccharide. This study presents the current knowledge of physiology and biochemistry of primary and secondary metabolisms
of basidiomycetes, and degradation mechanism of lignin. A better understanding of the ligninolytic activity of white-rot fungi
will impact the CELSS Program by providing insights on how edible fungi might be used to recycle the inedible portions of
the crops. 相似文献
8.
Oskar Faix 《Mikrochimica acta》1988,94(1-6):21-25
Based on own research activities this survey demonstrates the potential applications of FTIR spectroscopy in wood and wood-product research. This rapid method can be used e.g. with success for determination of lignin in woody materials and pulps. Crucial analytical data of lignins were also determined by quantitative evaluation of FTIR data. The degree of substitution of cellulose derivatives can be estimated. The course of delignification during pulping was monitored using transmission and circular ATR cells for the IR spectroscopy of the cooking liquors. Based on these spectra the Kappa number of pulps can be predicted. 相似文献
9.
William Doherty Peter Halley Les Edye David Rogers Francisco Cardona Yoosup Park Tim Woo 《先进技术聚合物》2007,18(8):673-678
Sugarcane fiber (i.e. bagasse) lignin has a larger fraction of aromatics unsubstitution in the ortho position than hardwood or softwood lignin and hence has the greater ability to be derivatized. Furthermore, organosolv lignin has a higher purity than sulfonated and kraft lignins. This work examines the purification of organosolv lignin derived from bagasse and the physico‐chemical properties of the lignin and lignin‐phenol formaldehyde (PF) resin coatings, and composites. The wetability tests have shown that lignin and lignin‐PF resin films are effective water barrier coatings, though the contact angles of lignin‐PF resin films were considerably less than the wax films. The overall mechanical properties (i.e. peak stress, peak strain and modulus) of the bagasse fiber composites were lower than the values obtained with the composites without the inclusion of bagasse fiber. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
10.
The effect of carbon and nitrogen sources, lignocellulosic substrates, and metal ions on lignin peroxidase (LiP) activity
of Aspergillus sp., which was isolated from a mangrove area, was studied. Glucose (1%) was found to be the best carbon source. Among the
various lignocellulosic substrates used, coir pith at 3% concentration increased LiP activity twofold on the second day of
incubation. Peptone and KNO3 completely inhibited the enzyme synthesis while (NH4)2SO4 at 12.5 mM produced maximum activity. Since seawater contained all the requisite metal ions, any added ions had a negative effect on
activity. Cu2+ had the most inhibiting effect while K+ the least. When all the optimized conditions were provided, in nitrogen- and carbon-sufficient medium, a maximum LiP activity
of 345 U/mL was obtained on the second day of incubation. 相似文献