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61.
The simultaneous action of shear deformation and high pressure (SDHP) creates changes in the structure of wood and its main
components (cellulose, hemicelluloses, lignin). The formation of water and alkali soluble polysaccharides under SDHP action,
proceeds in seconds in the solid state, without the use of any reagents and solvents. Therefore, SDHP seems to be a technologically
safe method and friendly to the environment. The amorphization of cellulose crystallites and depolymerization of cellulose
chains were observed under a wide range of pressures (1–6 GPa), both for cellulose samples and the cellulose part of wood.
Similar depolymerization occurs in the hemicellulose part of wood. The decomposition of polysaccharides under SDHP causes
the formation of the water soluble part, whose content increases with pressure and the applied shear deformation. A maximum
solubility of 40% and 55% was registered at 6 GPa following treatment of cellulose and birch wood samples. A higher output
in the case of wood can be explained by a specific role of lignin under SDHP, which acts as a ‘grinding stone’ during cellulose
and hemicelluloses destruction. As shown by high-performance size exclusion chromatography, the water soluble fraction obtained
from cellulose contained glucose (2.6%), cellobiose (9.6%), cellotriose (16.6%) and other higher water soluble oligomers (71%).
Almost complete dissolution (98%) of the treated cellulose sample can be achieved by extraction with 10% NaOH solution. The
SDHP treated birch wood was subjected to submerged fermentation (with Trichoderma viride), and a 13% output of proteins was
obtained. In this case, the water soluble part played the role of the so called ‘start sugars’. Abbreviations: ASF, alkali
soluble fraction; DP, degree of polymerization; EC, energy consumption; HP, high pressure; LMWS, low molecular weight sugars;
MC, moisture content; MCC, microcrystalline cellulose; SD, shear deformation, SDHP, shear deformation under high pressure;
SS, shear strength; WSF, water soluble fraction
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
62.
Yusuke Sasaki Toshiyuki Takagi Keisuke Motone Toshiyuki Shibata Kouichi Kuroda 《Bioscience, biotechnology, and biochemistry》2018,82(8):1459-1462
A co-culture platform for bioethanol production from brown macroalgae was developed, consisting of two types of engineered Saccharomyces cerevisiae strains; alginate- and mannitol-assimilating yeast (AM1), and cellulase-displaying yeast (CDY). When the 5% (w/v) brown macroalgae Ecklonia kurome was used as the sole carbon source for this system, 2.1 g/L of ethanol was produced, along with simultaneous consumption of alginate, mannitol, and glucans. 相似文献
63.
64.
Hak Sung Lee 《Biotechnology and Bioprocess Engineering》1997,2(2):126-131
The biosorption and desorption of Cr, Cu and Al were carried out using brown marine algaeSargassum fluitans biomass, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by
physical and chemical pretreatment. The maximum uptake of Cr, Cu and Al was independent of the alginate content. The maximum
uptake of Al was two times(mole basis) than those of Cu and Cr. The aluminum-alginate complex was found in the sorption solution
of raw and protonated biomass. Most of Cu, Al and light metals sorbed in the biomass were eluted at pH 1.1. However, only
5 to 10% of Cr sorbed was eluted at pH 1.1. The stoichometric ion exchange between Cu and Ca ion was observed on Cu biosorption
with Ca-loaded biomass. A part of Cr ion was bound to biomass as Cr(OH)2
+ or Cr(OH)2+. Al was also bound to biomass as multi-valence ion and interfered with the desorbed Ca ion. The behavior of rawS. fluitans in ten consecutive sorption-desorption cycles has been investigated in a packed bed flow-through-column during a continuous
removal of copper from a 35 mg/L aqueous solution at pH 5. The eluant used was a 1%(w/v) CaCl/HCl solution at pH3. 相似文献
65.
It was found that alginate binds to glucoamylase, presumably through the recognition of starch binding domain of the latter. The present work exploits this for purification of glucoamylases from commercial preparation of Aspergillus niger and crude culture filtrate of Bacillus amyloliquefaciens by affinity precipitation technique in a single-step protocol. Glucoamylase is selectively precipitated using alginate as macroaffinity ligand and later eluted with 1.0 M maltose. In the case of A. niger, 81% activity is recovered with 28-fold purification. The purified glucoamylase gave a single band on SDS-PAGE corresponding to 78 kDa molecular weight. The developed affinity precipitation process also works efficiently for purification of Bacillus amyloliquefaciens glucoamylase from its crude culture filtrate, giving 78% recovery with 38-fold purification. The purified preparation showed a major band corresponding to 62 kDa and a faint band about 50 kDa on SDS-PAGE. The latter corresponds to the molecular weight for alpha-amylase of Bacillus amyloliquefaciens. 相似文献
66.
Summary The development of nuclei and cytoplasmic microtubules was studied in the maturing spermatids of the grasshopper, Acrida lata, fixed with glutaraldehyde-potassium bichromate-osmium tetroxide and embedded in epoxy Epon-resin. Utilization of microkaryosomes for the formation of paracrystalline nucleoprotein is suggested by the fact that they are no longer visible in the advanced spermatid nuclei showing the paracrystalline structure. The cytoplasmic microtubules approximately 220 Å in diameter develop in close association with a linear material similar in density to the nuclear envelope. Only a single layer of the double-layered nuclear envelope is visible during the development of microtubules. Although cytoplasmic microtubules are assumed to have several physiological functions, such apparatus seem to be related to the polymerization of nucleoproteins as well, since the depolymerization of nucleoproteins occurs simultaneously along with the disappearance of cytoplasmic microtubules. 相似文献
67.
M. Alcalde F.J. Plou A. Gómez de Segura M. Remaud-Simeon R.M. Willemot P. Monsan A. Ballesteros 《Biotechnology Techniques》1999,13(11):749-755
Dextransucrase from Leuconostoc mesenteroides NRRL B-512F was immobilized using two different methods: covalent attachment to activated silica and entrapment in calcium alginate. For immobilization on silica, native enzyme and dextran-free enzyme were compared. However, the entrapment in calcium alginate beads gave the best results in terms of immobilization yield and stability. This biocatalyst was employed in the acceptor reaction with maltose showing similar glucooligosaccharide production than the native enzyme but increased operational stability. 相似文献
68.
A Laca L A García F Argüeso M Díaz 《Journal of industrial microbiology & biotechnology》1999,23(3):155-165
A microscopic technique has been developed to obtain the protein profiles inside calcium alginate gel. To do this, the diffusion
of BSA, previously marked with FITC, inside calcium alginate beads was observed using confocal laser microscopy, thus obtaining
the spatio-temporal evolution of the protein concentration. The technique, however, presents certain limitations and zones
where it is impossible to obtain experimental data. Wavelets analysis, commonly used in signal processing and statistics,
was employed to reconstruct and subsequently analyse the experimental results. Once the diffusion model was defined, the substrate
profiles obtained were used to calculate a diffusivity value for BSA in alginate gel.
Received 09 February 1999/ Accepted in revised form 14 May 1999 相似文献
69.
Shubhant Pandey Pranjal Mahanta Bryan W. Berger Rudresh Acharya 《The Journal of biological chemistry》2021,297(4)
Polysaccharide lyases (PLs) are a broad class of microbial enzymes that degrade anionic polysaccharides. Equally broad diversity in their polysaccharide substrates has attracted interest in biotechnological applications such as biomass conversion to value-added chemicals and microbial biofilm removal. Unlike other PLs, Smlt1473 present in the clinically relevant Stenotrophomonas maltophilia strain K279a demonstrates a wide range of pH-dependent substrate specificities toward multiple, diverse polysaccharides: hyaluronic acid (pH 5.0), poly-β-D-glucuronic (celluronic) acid (pH 7.0), poly-β-D-mannuronic acid, and poly-α-L-guluronate (pH 9.0). To decode the pH-driven multiple substrate specificities and selectivity in this single enzyme, we present the X-ray structures of Smlt1473 determined at multiple pH values in apo and mannuronate-bound states as well as the tetra-hyaluronate-docked structure. Our results indicate that structural flexibility in the binding site and N-terminal loop coupled with specific substrate stereochemistry facilitates distinct modes of entry for substrates having diverse charge densities and chemical structures. Our structural analyses of wild-type apo structures solved at different pH values (5.0–9.0) and pH-trapped (5.0 and 7.0) catalytically relevant wild-type mannuronate complexes (1) indicate that pH modulates the catalytic microenvironment for guiding structurally and chemically diverse polysaccharide substrates, (2) further establish that molecular-level fluctuation in the enzyme catalytic tunnel is preconfigured, and (3) suggest that pH modulates fluctuations resulting in optimal substrate binding and cleavage. Furthermore, our results provide key insight into how strategies to reengineer both flexible loop and regions distal to the active site could be developed to target new and diverse substrates in a wide range of applications. 相似文献
70.
Anandwardhan A. Hardikar Makarand V. Risbud Ramesh R. Bhonde 《Journal of biosciences》1999,24(3):371-376
Techniques for immunoisolation and immobilization of viable cells within semipermeable microcapsules have been developed using
highly sophisticated droplet generator systems. We propose here an indigenously designed, simple and efficient droplet generator
system for encapsulation of the pancreatic islets employing chitosanalginate matrix. The droplet generator system comprises
of a needle assembly, a 3-way valve with extended rubber tubing and a filtration unit connected to a pressure pump. Microbeads
of the size of around 400 μm diameter or even lesser (minimun attainable size 20.2 μm) could be easily generated using the
droplet generator system proposed here. Islet microcapsules cultured in Roswell Park Memorial Institute (RPMI) 1640 with 10%
fetal calf serum showed around 98% viability, comparable to that of the non-encapsulated islets. Transplantation of microencapsulated
islets to streptozotocin (STZ)-induced diabetic mice, resulted in disappearance of hyperglycemia and restoration of normoglycaemia
during a 30-day follow-up suggesting graft functionality. No graft failures were observed in any of the transplanted mice
(n = 15) and none of them showed membrane associated fibrous overgrowth, which can be attributed to the fibroblast-growth inhibitory
properties of chitosan. The proposed design appears to be superior in its simplicity and cost effectiveness and comparable
in performance with the microcapsule generator designs proposed so far. The proposed system can be further exploited for encapsulation
and immunoisolation of various cell types in alginate based matrices. 相似文献