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PubMed1996

Biodegradation of cellulose acetate by Neisseria sicca.

Bacteria capable of assimilating cellulose acetate, strains SB and SC, were isolated from soil on a medium containing cellulose acetate as a carbon source, and identified as Neisseria sicca. Both strains degraded cellulose acetate membrane filters (degree of substitution, DS, mixture of 2.8 and 2.0) and textiles (DS, 2.34) in a medium containing cellulose acetate (DS, 2.34) or its oligomer, but were not able to degrade these materials in a medium containing cellobiose octaacetate. Biodegradation of cellulose acetate (DS, 1.81 and 2.34) on the basis of biochemical oxygen demand reached 51 and 40% in the culture of N. sicca SB and 60 and 45% in the culture of N. sicca SC within 20 days. A decrease in the acetyl content of degraded cellulose acetate films and powder was confirmed by infrared and nuclear magnetic resonance analyses. After 10-day cultivation of N. sicca SB and SC, the number-average molecular weight of residual cellulose acetate decreased by 9 and 5%, respectively. Activities of enzymes that released acetic acid and produced reducing sugars from cellulose acetate were mainly present in the culture supernatant. Reactivity of enzymes for cellulose acetate (DS, 1.81) was higher than that for cellulose acetate (DS, 2.34).

Acetic Acid↗
PubMed2003

Dietary cellulose has no effect on the regeneration of hemoglobin in growing rats with iron deficiency anemia.

The objective of the present study was to determine the effect of cellulose on intestinal iron absorption in rats during recovery from iron deficiency anemia. Twenty-one-day-old male Wistar-EPM rats were fed an iron-free ration for two weeks to induce anemia. At 5 weeks of age, the rats were divided into two groups (both groups receiving 35 mg of elemental iron per kg diet): cellulose group (N = 12), receiving a diet containing 100 g of cellulose/kg and control (N = 12), receiving a diet containing no cellulose. The fresh weight of the feces collected over a 3-day period between the 15th and 18th day of dietary treatment was 10.7 +/- 3.5 g in the group receiving cellulose and 1.9 +/- 1.2 g in the control group (P<0.001). Total food intake was higher in the cellulose group (343.4 +/- 22.0 g) than in the control (322.1 +/- 13.1 g, P = 0.009) during the 3 weeks of dietary treatment. No significant difference was observed in weight gain (cellulose group = 132.8 +/- 19.2, control = 128.0 +/- 16.3 g), hemoglobin increment (cellulose group = 8.0 +/- 0.8, control = 8.0 +/- 1.0 g/dl), hemoglobin level (cellulose group = 12.3 +/- 1.2, control = 12.1 +/- 1.3 g/dl) or in hepatic iron levels (cellulose group = 333.6 +/- 112.4, control = 398.4 +/- 168.0 g/g dry tissue). We conclude that cellulose does not adversely affect the regeneration of hemoglobin, hepatic iron level or the growth of rats during recovery from iron deficiency anemia.

Anemia, Iron-Deficiency↗
PubMed1980

Gastrointestinal responses to graded levels of cellulose feeding in conventional and germ-free mice.

Conventional (CV) and germ-free (GF) mice were fed on a semi-synthetic diet containing graded levels of cellulose (0, 5, 15 and 30%), and thereafter the length and wet weight of intestine, the morphology of mid-jejunum epithelium and the turnover of mid-jejunum epithelial cells were determined. The following results were obtained. enlarged stomachs were observed in CV mice fed on a non-cellulose or 30% cellulose diet, but there were no differences found among the four dietary groups in GF mice. On the other hand, no effect of intestinal bacteria was observed, at least with regard to caecum weight, since the responses of caecum wet weight to the graded cellulose intake in CV mice were similar to those in GF mice. The responses of intestine length to graded cellulose intake differed between CV and GF mice, indicating that intestinal bacteria may modify the length of intestine in some way. Marked differences were observed in the responses of villus length to graded levels of cellulose between CV and GF mice. That is, in CV mice there was a gradual increase in villus length as cellulose content increased, whereas in GF mice there was a marked decrease in villus length. In the CV mice, graded levels of dietary cellulose had no effect on the epithelial cell turnover. On the other hand, in the GF mice it was observed that the greater the amount of dietary cellulose, the faster the turnover rate becomes. As a result, dietary cellulose would enhance the turnover rates of jejunal epithelial cells only in the absence of intestinal bacteria.

Animals↗
PubMed2001

Carbon partitioning to cellulose synthesis.

This article discusses the importance and implications of regulating carbon partitioning to cellulose synthesis, the characteristics of cells that serve as major sinks for cellulose deposition, and enzymes that participate in the conversion of supplied carbon to cellulose. Cotton fibers, which deposit almost pure cellulose into their secondary cell walls, are referred to as a primary model system. For sucrose synthase, we discuss its proposed role in channeling UDP-Glc to cellulose synthase during secondary wall deposition, its gene family, its manipulation in transgenic plants, and mechanisms that may regulate its association with sites of polysaccharide synthesis. For cellulose synthase, we discuss the organization of the gene family and how protein diversity could relate to control of carbon partitioning to cellulose synthesis. Other enzymes emphasized include UDP-Glc pyrophosphorylase and sucrose phosphate synthase. New data are included on phosphorylation of cotton fiber sucrose synthase, possible regulation by Ca2+ of sucrose synthase localization, electron microscopic immunolocalization of sucrose synthase in cotton fibers, and phylogenetic relationships between cellulose synthase proteins, including three new ones identified in differentiating tracheary elements of Zinnia elegans. We develop a model for metabolism related to cellulose synthesis that implicates the changing intracellular localization of sucrose synthase as a molecular switch between survival metabolism and growth and/or differentiation processes involving cellulose synthesis.

Amino Acid Sequence↗
PubMed1981

A simple, efficient method for coupling DNA to cellulose. Development of the method and application to mRNA purification.

A simple, efficient method to couple covalently DNA to cellulose is described. It utilizes the bifunctional oxirane 1,4-butanediol diglycidyl ether to activate cellulose and subsequently to link DNA to the cellulose. The optimal conditions for the latter reaction included use of a dehydration technique whereby DNA and activated cellulose were allowed to react on a glass slide in 0.1 N NaOH. Initial volume of the reaction was important; less than or equal to 250 microliters/50 mg cellulose was necessary for maximum efficiency. At DNA concentrations of less than or equal to 4 micrograms/mg cellulose, efficiency of binding was 90%. Binding studies using nucleotide homopolymers indicated that the order of the relative efficiencies of binding was poly(dT) greater than poly(dC) = poly(dA) greater than poly(dG). DNAs subjected to the binding conditions had an average of 0-1 breaks/molecule (for a 915-base DNA). A cloned double-stranded cDNA was coupled to cellulose by this technique. The cDNA was coupled to cellulose by this technique. The DNA-cellulose matrix was successfully used to purify the complementary mRNA from total poly(A)-enriched RNA by affinity chromatography. This method is very simple and highly efficient and can be conveniently adapted for the covalent coupling of various DNA species to cellulose for affinity chromatography.

Animals↗
PubMed1997

Clinical characterization of Dicea a new cellulose membrane for haemodialysis.

A prospective randomised clinical study comparing the functional performance and biocompatibility of a new cellulose diacetate variant (Dicea) in which the degree of hydroxyl group substitution differs, with cellulose diacetate and low flux polysulfone incorporated into commercially produced hollow fiber hemodialysers with a surface area 1.5-1.6 m2 has been undertaken. All dialysers studied demonstrated clinically acceptable performance in terms of their small molecular removal characteristics, with minor statistical but not clinical differences. Use of both cellulose diacetate membranes but not low flux polysulfone resulted in a reduction in plasma beta(2) microglobulin levels. The membranes were impermeable to albumin, but showed some permeability to low molecular weight proteins. The average protein recovery from the dialysis fluid was 3105 mg for Dicea, 2913 mg for cellulose diacetate and 2842 mg for low flux polysulfone. For Dicea the white cell count by 15 minutes had declined to 68% of pre treatment value, compared with 59% and 86% for cellulose diacetate and low flux polysulfone. The differences between Dicea and cellulose diacetate were not significant, but both cellulose based membranes differed from low flux polysulfone (p = 0.0015). There was a strong evidence of differences between the membranes in respect of C5a and C5b-9 generation (p = 0.0001) but not for C3a (p = 0.16) furthermore the levels of C5b-9 generated during dialysis also showed a significant positive correlation compared to C5a for all membranes. (Pearson's correlation coefficient = 0.856, p = 0.0001). It is concluded that the two cellulose diacetate membranes are not identical, with the differences observed being a consequence of the degree of acetyl substitution, resulting in alteration of membrane structure and the method of sterilization. The clinical significance of these differences are difficult to characterize but the modification of the cellulose structure appears to be a promising method to improve the biocompatibility of cellulose membranes. The improved biocompatibility offered by this method still falls short of that achieved with low flux synthetic membranes such as Fresenius Polysulfone.

Adult↗
PubMed2004

The evolutionary origin of animal cellulose synthase.

Urochordates are the only animals that produce cellulose, a polysaccharide existing primarily in the extracellular matrices of plant, algal, and bacterial cells. Here we report a Ciona intestinalis homolog of cellulose synthase, which is the core catalytic subunit of multi-enzyme complexes where cellulose biosynthesis occurs. The Ciona cellulose synthase gene, Ci-CesA, is a fusion of a cellulose synthase domain and a cellulase (cellulose-hydrolyzing enzyme) domain. Both the domains have no animal homologs in public databases. Exploiting this fusion of atypical genes, we provided evidence of a likely lateral transfer of a bacterial cellulose synthase gene into the urochordate lineage. According to fossil records, this likely lateral acquisition of the cellulose synthase gene may have occurred in the last common ancestor of extant urochordates more than 530 million years ago. Whole-mount in situ hybridization analysis revealed the expression of Ci-CesA in C. intestinalis embryos, and the expression pattern of Ci-CesA was spatiotemporally consistent with observed cellulose synthesis in vivo. We propose here that urochordates may use a laterally acquired "homologous" gene for an analogous process of cellulose synthesis.

Amino Acid Sequence↗
PubMed2002

Recent progress in cellulose biosynthesis.

Cellulose comprises the major polymer of the plant cell wall. It consists of a set of parallel chains composed of glucans and these chains are highly oriented to form a structure known as a microfibril. The orientation of the microfibrils controls the extension of the direction of the plant cell. Extensive studies on the cellulose biosynthesis have been carried out for over three decades, and recently (1996) genes for cellulose biosynthesis in plants ( CesA) were isolated. In the year 2002, a specific primer for cellulose biosynthesis reaction has been discovered and cellulose synthetic activity has been also confirmed by recombinant protein derived from the plant CesA gene. Furthermore, other proteins involved in cellulose biosynthesis besides CesA proteins were also proposed at the same time. One of these proteins, Korrigan cellulase, was suggested to act by removing sitosterol from the primer for biosynthesis reaction of cellulose. A membrane-bound sucrose synthase was also suggested to provide UDP-glucose as a substrate for cellulose biosynthesis. On the basis of these results, a new pathway for cellulose biosynthesis was proposed. Now, the research field of cellulose biosynthesis is facing a major turning point.

Journal Article↗
PubMed1998

Pretreatment for cellulose hydrolysis by carbon dioxide explosion

Cellulosic materials were treated with supercritical carbon dioxide to increase the reactivity of cellulose, thereby to enhance the rate and the extent of cellulose hydrolysis. In this pretreatment process, the cellulosic materials such as Avicel, recycled paper mix, sugarcane bagasse and the repulping waste of recycled paper are placed in a reactor under pressurized carbon dioxide at 35 degreesC for a controlled time period. Upon an explosive release of the carbon dioxide pressure, the disruption of the cellulosic structure increases the accessible surface area of the cellulosic substrate to enzymatic hydrolysis. Results indicate that supercritical carbon dioxide is effective for pretreatment of cellulose. An increase in pressure facilitates the faster penetration of carbon dioxide molecules into the crystalline structures, thus more glucose is produced from cellulosic materials after the explosion as compared to those without the pretreatment. This explosion pretreatment enhances the rate of cellulosic material hydrolysis as well as increases glucose yield by as much as 50%. Results from the simultaneous saccharification and fermentation tests also show the increase in the available carbon source from the cellulosic materials for fermentation to produce ethanol. As an alternative method, this supercritical carbon dioxide explosion has a possibility to reduce expense compared with ammonia explosion, and since it is operated at the low temperature, it will not cause degradation of sugars such as those treated with steam explosion due to the high-temperature involved.

Journal Article↗
PubMed1994

The Effect of Xyloglucans on the Degradation of Cell-Wall-Embedded Cellulose by the Combined Action of Cellobiohydrolase and Endoglucanases from Trichoderma viride.

Two endoglucanases of Trichoderma viride, endoI and endoIV, were assayed for their activity toward alkali-extracted apple xyloglucans. EndoIV was shown to have a 60-fold higher activity toward xyloglucan than endoI, whereas carboxymethyl cellulose and crystalline cellulose were better substrates for the latter. The enzymic degradation of cellulose embedded in the complex cell-wall matrix of apple fruit tissue has been studied using cellobiohydrolase (CBH) and these two different endoglucanases. A high-performance liquid chromatographic method (Aminex HPX-22H) was used to monitor the release of cellobiose and oligomeric xyloglucan fragments. Synergistic action between CBH and endoglucanases on cell-wall-embedded cellulose was, with respect to their optimal ratio, slightly different from that reported for crystalline cellulose. The combination of endoIV and CBH solubilized twice as much cellobiose compared to a combination of endoI and CBH. Apparently, the concomitant removal of the xyloglucan coating from cellulose microfibrils by endoIV is essential for an efficient degradation of cellulose in a complex matrix. Cellulose degradation slightly enhanced the solubilization of xyloglucans. These results indicate optimal degradation of cell-wall-embedded cellulose by a three-enzyme system consisting of an endoglucanase with high affinity toward cellulose (endoI), a xyloglucanase (endoIV), and CBH.

Journal Article↗
PubMed1983

[Effects of the isoenzymes of endoglucanase from Trichoderma longibrachiatum differing in their ability to be adsorbed on cellulose and on soluble, amorphous and crystalline substrates: a different role of adsorption efficiency].

The mode of action of two purified endoglucanase (Mr 42 000) from Trichoderma longibrachiatum on soluble CM-cellulose as well as on amorphous and crystalline celluloses was studied. Both enzymes had the same Km values for CM cellulose (1.4 g/l), similar V values (51 and 47 mumole . min . mg of protein) and synthesized glucose and cellobiose from CM-cellulose in comparable amounts. However, the enzymes differed essentially in their ability to be adsorbed on soluble cellulose, i. e. their partition coefficients (cellulose surface/bulk solution) differed by one order of magnitude. When the enzyme concentrations on the cellulose surface were equal (in two independent experiments), the rate of degradation of amorphous (but not crystalline) cellulose was also almost identical. However, when crystalline cellulose was subjected to hydrolysis, the more tightly adsorbed enzyme revealed the initial solubilizing activity which was 20 times greater than that of the less tightly adsorbed enzyme (at the same endoglucanase activity on the surface). In the presence of high cellobiase concentrations sufficient to convert all intermediate cellobiose into glucose the effectively adsorbed endoglucanase was capable to convert at least 50% of crystalline cellulose to glucose.

Enzymes, Immobilized↗
PubMed1980

Modes of action of exo- and endo-cellulases in the degradation of celluloses I and II.

Cotton and Valonia-cellulose (cellulose I) were readily attacked by endo-cellulase of a highly endowise-hydrolysis type, with a sharp decrease in the degree of polymerization, while the simultaneous production of reducing sugar was low. In contrast, viscose rayon and alkali-cellulose (cellulose II) showed little lowering of the degree of polymerization by endo-cellulase, though the effect was slightly greater than with an exo-cellulase, while the simultaneous production of reducing sugar was very high. The synergistic effect of exo- and endo-cellulases on the hydrolysis of cellulose was much higher with cellulose I than with cellulose II. These results can be explained in terms of differences in the polarity of cellulose chains and in the crystallinity and/or ultrastructure of the cellulose fibers.

Cellulase↗
PubMed2004

Quantitative analysis of cellulose-reducing ends.

Methods for the quantification of total and accessible reducing ends on traditional cellulose substrates have been evaluated because of their relevance to enzyme-catalyzed cellulose saccharificaion. For example, quantification of accessible reducing ends is likely to be the most direct measure of substrate concentration for the exo-acting, reducing end-preferring cellobiohydrolases. Two colorimetric assays (dinitrosalicylic acid [DNS] and bicinchoninic acid [BCA] assay ) and a radioisotope approach (NaB3H4 labeling) were evaluated for this application. Cellulose substrates included microcrystalline celluloses, bacterial celluloses, and filter paper. Estimates of the number of reducing ends per unit mass cellulose were found to be dependent on the assay system (i.e. the DNS and BCA assays gave strikingly different results). DNS-based values were several-fold higher than those obtained using the BCA assay, with fold-differences being substrate specific. Sodium borohydride reduction of celluloses, using cold or radiolabeled reagent under relatively mild conditions, was used to assess the number of surface (solvent-accessible) reducing ends. The results indicate that 30-40% of the reducing ends on traditional cellulose substrates are not solvent accessible; that is, they are buried in the interior of cellulose structures and thus not available to exo-acting enzymes.

Biotechnology↗
PubMed2002

Release of salbutamol sulphate and ketoprofen enantiomers from matrices containing HPMC and cellulose derivatives.

We studied the release of salbutamol and ketoprofen enantiomers from HPMC K100M matrices containing two types of cellulose derivatives: cellulose tris (3,5-dimethylphenylcarbamate) and cellulose tris (2,3-dichlorophenylcarbamate), chiral excipients used as stationary phases for liquid chromatography. These matrices provided an extended release of both drugs. Ketoprofen release from formulations elaborated with cellulose tris (2,3-dichlorophenylcarbamate) was by anomalous transport, because the value of n (release exponent of the diffusion equation) ranged between 0.60-0.68, whereas for all other formulations the value of exponent n ranged from 0.50-0.54. The drug thus diffuses through the matrix and is released following a quasi-Fickian diffusion mechanism (stereoselective process). The matrices preferentially retained R-salbutamol and S-ketoprofen and cellulose tris (3,5-dimethylphenylcarbamate) showed more capacity of chiral discrimination for both drugs than cellulose tris (2,3-dichlorophenylcarbamate). Moreover, we observed that stereoselectivity is dependent on the amount of chiral excipient in the formulation. Diffusion tests confirmed the chiral interaction between drugs and cellulose derivatives observed in the dissolution assays except for matrices elaborated with ketoprofen and cellulose tris (2,3-dichlorophenylcarbamate), where the low stereoselectivity observed with the matrices is due to the presence of HPMC K100M. We conclude that the inclusion of these cellulose derivatives in HPMC matrices does not result in a relevant stereoselectivity with respect to the two drugs studied.

Albuterol↗
PubMed1989

Tissue biocompatibility of cellulose and its derivatives.

Tissue biocompatibility of cellulose and its derivatives was examined in two in vivo tests, one for absorbance by living tissue and one for foreign body reaction. The samples examined were regenerated celluloses and cellulose derivatives: methyl cellulose, ethyl cellulose, aminoethyl cellulose, hydroxyethyl cellulose, and cellulosic polyion complexes. The in vivo absorbance by living tissue was found to depend on the degree of crystallinity and the chemical structure of the sample. The foreign body reaction was relatively mild for all the samples examined, showing that cellulose can be converted to biocompatible materials by physical and/or chemical transformation.

Animals↗
PubMed1992

The cellulose paradox: pollutant par excellence and/or a reclaimable natural resource?

The various aspects of cellulose as a pollutant are considered in view of its lack of toxicity on the one hand and its recalcitrant durable nature on the other. The microbial degradation of cellulosics is discussed, and the contrast between its success in handling natural cellulosic wastes versus its failure to cope with man-made refuse is described. Research carried out in the past decade has demonstrated that cellulolytic organisms are provided with cell surface multifunctional multienzyme conglomerates, called cellulosomes, which are capable of solubilizing solid cellulosic substrates. The intriguing properties of such complexes include their cohesive nature, their many enzymatic components, and a characteristic glycosylated cellulose-binding, 'scaffolding' component. The latter appears to serve as a substrate-targeting carrier, which delivers the other (hydrolytic) components to the cellulose. Progress in establishing efficient model systems for in vitro solubilization of purified cellulose or natural cellulosic substrates has been achieved using purified cellulosome preparations, fortified with beta-glucosidase and pectinase. The latter enzymes were required in order to alleviate the phenomenon of product inhibition which reduces the efficiency of the free cellulosome. Such combined enzyme systems are proposed as examples of future tailor-made cellulolytic systems for the degradation of natural cellulosics.

Biodegradation, Environmental↗
PubMed1993

Preliminary experimental study on a newly-developed coating material (liquid cellulose) for cerebral aneurysms.

We have developed a new coating material for cerebral aneurysms consisting of cellulose. The possible usefulness of this ethyl cellulose-ethyl acetate solution ("Liquid cellulose") as a coating material was evaluated as follows: 1) The liquid cellulose (ethyl cellulose concentration, 10%; degree of polymerization, 100) and Biobond had pHs of 7.35 and 3.16, and viscosities of 1,385 and 626 cp, respectively. The properties of the coat (N = 30, M +/- SD) of the liquid cellulose and Biobond at a cast coat thickness of 254 microns were as follows: coat thickness after drying (microns), 17.8 +/- 2.8 and 109.8 +/- 44.2; coat formation time (sec), 62 and 1,800; strength of the coat (gm), 432.3 +/- 51.4 and 8.0 +/- 5.6; strength index (kg/cm2), 572.8 +/- 84.7 and 2.4 +/- 1.8; and elongation index (%), 14.8 +/- 3.5 and 705 +/- 188.8, respectively. The coat using liquid cellulose was more physiological and far stronger. It was also more readily manipulated during the operation than Biobond. 2) The liquid cellulose showed excellent adhesiveness when applied to the vascular wall. Sequential histological observations for 12 months showed that the liquid cellulose remained stable without histotoxicity or cracks in the coat. These results indicate the potential usefulness of this agent for reinforcing the vascular wall.

Acetates↗
PubMed1991

Liquid crystal-type assembly of native cellulose-glucuronoxylans extracted from plant cell wall.

In numerous plant cell walls, the cellulose microfibrils are arranged in a helicoidal pattern which has been considered as an analog to a cholesteric order. Here, we report on the spontaneous helicoidal organization which occurs in acellular conditions from aqueous suspensions of cellulose. The cellulosic mucilage of mature seeds of quince (Cydonia oblonga L) was studied both in situ (pre-release mucilage) and after water extraction and in in vitro re-assembly (prolonged high speed ultracentrifugation, further progressive dehydration and embedding in LR White methacrylate or hydrosoluble melamine resin). The cellulosic component was characterized by the use of cellobiohydrolase (CBH1) bound to colloidal gold, and the glucuronic acid residues of the xylan matrix were characterized by the use of cationised gold. Inside the seeds, the pre-release mucilage is mostly helicoidal, with the occurrence of more or less ordered domains, which indicate a fluid organization relevant to an actual liquid crystal state. Cytochemical tests revealed the tight association between cellulose and glucuronoxylans, the latter constituting a charged coat around each microfibril. Following the hydration of the seed, a cellulosic suspension was extracted in which microfibrils were totally dispersed. The progressive dehydration of the suspension gave rise to concentrated viscous drops. Ultrastructural observations revealed the occurrence of multidomain organization, from non-ordered to cholesteric-like regions, revealing that the mucilage is at the same time crystalline and liquid. This constitutes the first demonstration that liquid crystal type assemblies can arise from crystalline and biological cellulose in aqueous suspension. It strengthens the hypothesis that a transient liquid crystal state must occur during the cellulose ordering. The possible morphogenetic role of the glucuronoxylans in the cholesteric organization of the cellulose is discussed.

Cell Wall↗