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221.
Lignosulfonates are abundantly available byproducts of the paper and pulping industry, and they therefore represent a promising feedstock for new sustainable processes. For industrial applications of lignosulfonates, their molecular weight distribution is a critical factor. In order to decrease the average molecular weight of lignosulfonates, Seventeen basidiomycetes were screened for their capability to depolymerize lignosulfonates from spent sulfite liquor (SSL) in surface and liquid cultures. Five basidiomycetes polymerized the lignosulfonates under the selected conditions. Only Irpex consors was found to efficiently degrade calcium lignosulfonates when SSL (0.5%, w/w) was used as the sole carbon and nitrogen source. The average molecular weight of the lignosulfonates was reduced from ∼26 to ∼4 kDa as determined by size exclusion chromatography (SEC) within two weeks. Various extracellular enzyme activities of I. consors were determined over the culture period. High peroxidase activities were correlating with a high degradation rate and the culture was harvested at the day of highest peroxidase activity. A putative versatile peroxidase was isolated by fast protein liquid chromatography (FPLC) and its encoding cDNA was cloned. 相似文献
222.
David Welch 《Inorganica chimica acta》2011,370(1):279-285
Heterometallic and homometallic nanoclusters of [Ag(CN)2]− and [Au(CN)2]− doped in NaCl, KCl, and NaBr exhibit interesting photophysical phenomenon that are related to the variety of sizes, orientations, and compositions these clusters adopt. Samples of various dopant-host systems have been grown and analyzed with luminescence spectroscopy. In order to predict what types of clusters are in these different systems, an atomistic surface model has been developed that probes the energetics of these clusters as they first form at surface kink sites. An order of preference in mixed-metal systems for heterometallic cluster formation over homometallic cluster formation, NaBr > NaCl > KCl, is predicted which agrees with findings on heterometallic cluster peaks in the luminescence spectra. Structural orientations are predicted to be very different in heterometallic clusters as opposed to homometallic clusters. 相似文献
223.
Densification of bulky forages by pelleting reduces their transportation, handling, and storage costs. Because of high shearing force and frictional heating during the pelleting process, it is hypothesized that pelleting of lignocellulosic biomass could also partially deconstruct its complex structure and facilitate bioethanol production. In this study, pelleted wheat straw, corn stover, big bluestem, and sorghum stalk were evaluated for sugars and ethanol production, and compared with those of unpelleted biomasses. Mass recovery after alkali pretreatment increased by 14%, 11%, 2%, and 5%, respectively, in unpelleted biomasses. Lignin content reduced significantly more in pelleted samples for all types of biomass, except sorghum stalk. Volumetric productivity of enzymatic hydrolysis was 23%, 21%, 20% and 12% higher, respectively, in pelleted samples; ethanol yield on the basis of released sugars did not differ significantly between pelleted and unpelleted samples. These results indicate that the pelleting process led to better enzymatic hydrolysis of pretreated biomasses without affecting the quality of sugars for fermentation. However, overall yield of ethanol from the raw biomass was not significantly higher in pelleted biomasses because of higher mass loss during pretreatment process. In our study, we propose a schematic for complete utilization of various byproducts for enhanced economic viability. 相似文献
224.
A. M. Calvo José L. Copa-Patiño Oriele Alonso A. E. González 《Archives of microbiology》1998,171(1):31-36
The basidiomycete Coriolopsis gallica decolorizes alkaline paper effluents efficiently. In this work, we found that C. gallica produces laccase during this decolorization process. This enzymatic activity was produced in all media studied; however,
the highest enzymatic activity was obtained in a medium containing paper effluent, where laccase was detected on the 2nd day
of the experiment. The laccase activity of C. gallica was purified and characterized. The amino-terminal sequence of this protein showed the highest similarity with the laccase
I of the basidiomycete PM1 and with Coriolus hirsutus laccase.
Received: 20 April 1998 / Accepted: 21 September 1998 相似文献
225.
Mutation at thealdox-2 locus inDrosophila melanogaster affects the specific activities of four molybdoenzymes differentially during development. Sulfite oxidase activity is normal during late larval and pupal stages but is reduced during early adult stages inaldox-2 organisms. There was complete concordance among the effects ofaldox-2 on sulfite oxidase, aldehyde oxidase, xanthine dehydrogenase, and pyridoxal oxidase, when 38 stocks were analyzed which were derived from single recombination events betweenc andpx, markers which flankaldox-2. Several different biochemical analyses indicate that the active molybdoenzymes present in thealdox-2 strain are normal with respect to size, shape,pH-activity profile,K
m
, and molecular weight. Significant differences were found between thealdox-2 strain and the OR control strain in their responses to dietary Na2MoO4 and Na2WO4. The mutant strain is much more resistant to the effects of dietary Na2WO4 and much more responsive to the administration of Na2MoO4 than the OR control strain when these effects are quantitated by measurements of molybdoenzyme specific activities. This evidence suggests that thealdox-2
+ gene product has a molybdenum binding site which can also bind tungsten and that this site is altered in the mutant strain. The hypothesis presented explains the observed effects of thealdox-2 mutation and relates them to the other mutations reported in this gene-enzyme system.This work was supported by an Operating Grant from the Natural Sciences and Engineering Research Council to M.M.B. 相似文献
226.
Roland Fischer Judith Baumgartner Christoph Marschner Frank Uhlig 《Inorganica chimica acta》2005,358(11):3174-3182
Starting from tetrakis(trimethylsilyl)stannane, the tris(trimethylsilyl)stannyl alkali derivatives (Me3Si)3SnM, (M = Li, Na, K, Rb, Cs) were prepared in excellent yields. Reaction with MgBr2 · Et2O afforded bis[tris(trimethylsilyl)stannyl]magnesium. Reaction products were investigated by means of multinuclear NMR spectroscopy. At low temperatures, coupling of 7Li and 119Sn between [(Me3Si)3Sn]− and [Li · 3THF]+ (337 Hz) or [Li · 12Cr4]+ (275 Hz), was observed. NMR chemical shifts and coupling constants of the stannyl anions exhibit a strong dependency on the nature of the cation, solvent system, concentration and temperature. In addition, the molecular structure of tris(trimethylsilyl)stannyl sodium · 15Cr5 was determined by X-ray crystallography. The [Na · 15Cr5]+ and [(Me3Si)3Sn]− units are joined by a direct Sn-Na contact, 3.0775(18) Å in length. 相似文献
227.
Shabina Yeasmin Shah Md. Asraful Islam Ji-Young Lee 《Preparative biochemistry & biotechnology》2016,46(3):229-237
The efficacy of different concentrations of NaOH (0.25%, 0.50%, 0.75%, and 1.00%) for the pretreatment of rice straw in solid and powder state in enzymatic saccharification and fermentation for the production of bioethanol was evaluated. A greater amount of biomass was recovered through solid-state pretreatment (3.74 g) from 5 g of rice straw. The highest increase in the volume of rice straw powder as a result of swelling was observed with 1.00% NaOH pretreatment (48.07%), which was statistically identical to 0.75% NaOH pretreatment (32.31%). The surface of rice straw was disrupted by the 0.75% NaOH and 1.00% NaOH pretreated samples as observed using field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). In Fourier-transform infrared (FT-IR) spectra, absorbance of hydroxyl groups at 1,050 cm?1 due to the OH group of lignin was gradually decreased with the increase of NaOH concentration. The greatest amounts of glucose and ethanol were obtained in 1.00% NaOH solid-state pretreated and powder-state hydrolyzed samples (0.804 g g?1 and 0.379 g g?1, respectively), which was statistically similar to the use of 0.75% NaOH (0.763 g g?1 and 0.358 g g?1, respectively). Thus, solid-state pretreatment with 0.75% NaOH and powder-state hydrolysis appear to be suitable for fermentation and bioethanol production from rice straw. 相似文献
228.
The effects of alkali type and the concentration in the alkali treatments on the weight loss in six cellulosic fibers and their influences on the fibrillation tendency were investigated. The fibril number of the cellulosic fibers pretreated with alkalis (FNpre) increased with increasing the alkali concentrations as well as the weight loss of the fiber except in the lyocell fiber treated in NaOH and KOH solutions. The FNpre in lyocell was reduced as the fibers were treated in 5 mol/l NaOH and KOH solutions. This result and the fact that the fibers were split in organic alkali such as tetramethylammonium hydroxide even at the low weight loss suggested that not only the loss of cellulose component but also reorganization of microfibril structure, inhomogeneous swelling of the fibers and other influences control the fibrillation tendency of cellulosic fibers. 相似文献
229.
Spent cherry brine is an acidic byproduct of maraschino cherry processing and typically consists of variable amounts of glucose
and fructose of up to 11% fermentable solids, 0.5–1.5% CaCl2, up to 0.4% sulfur dioxide, sorbitol, and lesser amounts of other cherry constituents. Disposal of brine represents a significant
cost to processors because of its high biological oxygen demand. As an alternative, brine was tested as a substrate for ethanol
production. Initially, the toxic level of sulfur dioxide was reduced by raising brine pH to 8.0 to precipitate calcium sulfite.
Because alkalinization was subsequently found to result in a 10-fold reduction in phosphorous, brines were titrated with
phosphoric acid to pH 6.0 prior to inoculation with Saccharomyces cerevisiae. All strains of Saccharomyces cerevisiae tested were able to ferment all lots of Ca(OH)2-treated and phosphorous-enriched brines efficiently. One lot of brine containing 10% (w/v) fermentable sugar yielded 4.7%
(w/v) ethanol in 4 days.
Received 24 December 1996/ Accepted in revised form 14 April 1997 相似文献