Showing papers on "Chitin published in 1982"
TL;DR: Trichoderma harzianum excreted β-1, 3-glucanase and chitinase into the medium when grown on laminarin and Chitin, respectively, or on cell walls of the pathogen Sclerotium rolfsii as discussed by the authors.
Abstract: Trichoderma harzianum excreted β-1, 3-glucanase and chitinase into the medium when grown on laminarin and chitin, respectively, or on cell walls of the pathogen Sclerotium rolfsii, as sole carbon s...
479 citations
TL;DR: Kinetic studies of the degradation reaction show that the hydrolysis of partially deacetylated chitin by lysozyme follows typical Michaelis-Menten kinetics with an apparent Km value of 45 micrograms/ml and a Vmax value of 0.083 x 10(-3) g/l/min.
263 citations
TL;DR: In this article, the use of cellulose-like biopolymers as functional additives for potential application in food formulations was studied, including water binding, fat binding and emulsifying properties.
Abstract: Chitin (poly-β (1⇒4)-N-acetyl-D-glucosamine), chitosan (deacetylated chitin) and microcrystalline chitin (redispersible chitin powder) were compared with microcrystalline cellulose to examine the use of those cellulose-like biopolymers as functional additives for potential application in food formulations. Water binding, fat binding and emulsifying properties were studied. Baking tests were performed with 0.5–2.0% (flour basis) of microcrystalline chitin added to wheat flour bread or to potato protein fortified (8% potato protein concentrate) white bread. Water-binding capacity and fat binding capacity of chitin, chitosan and microcrystalline chitin ranged from 230–440s (w/w) and from 170–315% (w/w). Chitosan and chitin did not produce emulsions but microcrystalline chitin showed good emulsifying properties and was superior to microcrystalline cellulose. Increasing concentration of microcrystalline chitin (0.12–0.8 g/100 ml water) had a positive effect on emulsion stability. Addition of microcrystalline chitin increased specific loaf volume of white bread and protein fortified breads. Water addition of 65% (flour basis) was found to be optimum for “chitin breads.”
172 citations
TL;DR: The extracellular chitinase produced by Serratia marcescens was obtained in highly purified form by adsorption-digestion on Chitin this article.
151 citations
TL;DR: It is shown that chitin, an important component of most fungal cell walls, elicited lignification in wheat leaves when applied as a suspension to wounds as well as the soluble derivatives ethylene glycol, ch itin and chitosan.
Abstract: Chitin, an important component of most fungal cell walls, elicited lignification in wheat leaves when applied as a suspension to wounds. The soluble derivatives ethylene glycol, chitin and chitosan were also active, but glucosamine, N-acetylglucosamine and small chitin oligomers did not elicit the response. The fungal glucan pullulan lacked activity, but laminarin, an algal glucan, was a weak elicitor. The response could also be elicited by fungal cell wall preparations. The possible role of chitin and related wall polymers in inducing host-defence mechanisms in wheat is discussed.
150 citations
TL;DR: In this article, the interaction of the natural marine polymer chitin and its deacetylated derivative chitosan with chromium has been investigated using atomic absorption spectroscopy.
Abstract: The interaction of the natural marine polymer chitin and its deacetylated derivative chitosan with chromium has been investigated. The uptake of chromium from aqueous solution was determined from changes in concentration as measured by atomic absorption spectroscopy. The uptake of Cr(III) on chitosan was significantly greater than that on chitin. The smaller the size fraction of the chitin/chitosan, the greater the uptake of Cr(III). The Cr(III) uptake increased with increasing solution pH. Minimal desorption of chromium was observed on washing previously chromium-equilibrated chitosan with distilled water. The uptake of Cr(III) by chitosan was enhanced in the presence of phosphate, whereas the converse was not observed. Minimal uptake of Cr(VI) as dichromate by chitin and chitosan was measured. Cr-containing nodules were noted in the SEM/EDAX analysis for Cr(III)-equilibrated chitosan. Cr-containing clusters were detected for Cr(III)- plus phosphate-equilibrated chitosan. XPS results supported the conclusions drawn from the isotherm studies.
113 citations
Journal Article•
TL;DR: The effect of amending soil with chitin on Meloidogyne arenaria (Neal) Chitwood was studied in a greenhouse experiment using silt loam [pH 6.5] from an infested peanut field as discussed by the authors.
Abstract: The effect of amending soil with chitin on Meloidogyne arenaria (Neal) Chitwood was studied in a greenhouse experiment using silt loam [pH 6.5, org. matter 1% (w/w)] from an infested peanut (Arachis hypogaea L.) field. Chitin was added to soil at rates of 0.5-4.0% (w/w). The chitin was allowed to decompose for 3 weeks, then the soil was planted with summer crookneck squash (Cucurbita pepo L.). After 6 weeks of growth, squash plants were examined to determine the level of root galling and the soil was analyzed for soil enzymic activity and microbial populations. No galls were found on plants from soil with 1% or more of chitin. Soils with 0.5 to 2.0% chitin produced plants which were significantly taller and with heavier shoots than those from untreated soil or from soil with 4.0% chitin. Chitin treatments of 2.0% or higher significantly reduced germination of seed, and chitin at rates above 1.0% resulted in a significant reduction in root weight. Chitin amendments resulted in incre
105 citations
TL;DR: The method was used to assay the chitin in the mycelia of basidomycetes obtained in vitro and the measured amount of glucosamine was proportional to theMycelial biomass and allowed the estimation of fungal growth.
93 citations
TL;DR: An integrated process scheme for conversion of shrimp shell chitin waste to yeast single-cell protein based on these and previous results was designed and analyzed economically, giving a negative after-tax cash flow of $0.06 per kg of wet waste.
Abstract: Study of pretreatment of shrimp processing waste for a chitin bioconversion scheme to produce yeast single-cell protein established conditions for size reduction, deproteination, and demineralization. Enzymatic hydrolysis of pretreated chitin waste achieved 80% conversion in 24 hr. Optimum temperature and pH were determined for maximum chitinase production in submerged culture, using pretreated chitin waste as substrate. An integrated process scheme for conversion of shrimp shell chitin waste to yeast single-cell protein based on these and previous results was designed and analyzed economically, giving a negative after-tax cash flow of $0.06 per kg of wet waste.
93 citations
TL;DR: In vitro adherence of Candida albicans to human vaginal epithelial cells was studied and data suggest that the amino groups of sugars are responsible for the inhibition of adherence of this eucaryotic microorganism to epithelial Cells.
Abstract: In vitro adherence of Candida albicans to human vaginal epithelial cells was studied, aimed at identifying the surface components involved in this binding. The inhibitory effect of yeast cell wall components and their constituents on the adherence of yeasts to epithelial cells was tested. Only chitin, its hydrolysate derivative and N-acetylglucosamine, the constituent of chitin, acted as inhibitors. Binding was also inhibited by the amino sugars glucosamine and mannosamine, while none of the other sugars tested (methylated or nonmethylated) exhibited such an effect. These data suggest that the amino groups of sugars are responsible for the inhibition of adherence of this eucaryotic microorganism to epithelial cells.
TL;DR: It could not, however, be conclusively established whether protein and carbohydrate are covalently linked, because the chitinase is resistant to endo-beta-N-acetyl-glucosaminidase.
TL;DR: Constitutive chitinases were purified from healthy tomato stem and culture filtrates of a tomato isolate of Verticillium albo-atrum and increased activity in infected tissue was due primarily to increased production of the constitutive endo-enzyme found in healthy tomato stems.
Abstract: Constitutive chitinases were purified from healthy tomato stem and culture filtrates of a tomato isolate of Verticillium albo-atrum Both chitinases hydrolyzed chitin, chitosan and 3,4-dinitrophenyl-tetra- N -acetyl-β- d -chitotetraoside, but the tomato enzyme showed enhanced production of N -acetylglucosamine from chitin in the presence of chitobiase The tomato chitinase, purified to homogeneity, had a molecular weight of 27 000–31000 and functioned as an endo-enzyme The partially purified chitinase from V albo-atrum had a molecular weight of 63 000, appeared to be an exo-enzyme and was unaffected by the addition of chitobiase to the reaction mixture It differed from the tomato enzyme in the hydrolysis of chitobiose and in its inhibition by 2-acetamido-2-deoxy- d -gluconolactone The origin of increased chitinase activity in V albo-atrum -infected tomato stem was investigated by comparing the response of chitinase in extracts from healthy and infected stem to pH and temperature and by examining the patterns of activity in healthy and infected stem extracts after gel isoelectric-focusing The enzymes from healthy and infected stem and from V albo-atrum were also compared during the various purification stages The increased activity in infected tissue was due primarily to increased production of the constitutive endo-enzyme found in healthy tomato stems An additional chitinase similar to the fungal enzyme was also present
TL;DR: Mass-isolated imaginal discs of Drosophila melanogaster form a chitin-containing pupal procuticle In vitro and incorporation of [3H]glucosamine into chitan fraction is sensitive to inhibitors of protein, RNA and chit in synthesis, but has little sensitivity to inhibitor of DNA synthesis, and dolichol-dependent glycosylation.
TL;DR: It is suggested that chitin and chitosan may be suitable for use as diluents with friction-lowering properties in direct compression processes.
Abstract: As a part of a series of study on pharmaceutical applications of chitin and chitosan, the fluidity and compressibility of combined powders of lactose with chitin and chitosan, and potato starch with chitin and chitosan, as well as the disintegration properties of the tablets made from these powders were investigated in comparison with those of crystalline cellulose with lactose and potato starch. The lubricating properties of combined powders of lactose with chitin and chitosan were also investigated in comparison with those of lactose with crystalline cellulose. The fluidity of combined powders with chitin and chitosan was greater than that of the powder with crystalline cellulose. The hardest tablet was obtained with chitosan, followed by crystalline cellulose and chitin in that order. Tablets containing less than 70% of chitin or chitosan passed the disintegration test of JP X. The ejection force of the tablets of lactose/chitin and lactose/chitosan was significantly smaller than that of lactose/crystalline cellulose tablets. It is suggested that chitin and chitosan may be suitable for use as diluents with friction-lowering properties in direct compression processes.
01 Jan 1982
TL;DR: The physical structures of cellulose and chitin are reviewed in this article, and the implications of these structures for studies of the biosynthesis of these two polymers are discussed.
Abstract: In this chapter, we will review what is currently known about the physical structures of cellulose and chitin and discuss the implications of these structures for studies of the biosynthesis of these two polymers. Cellulose and chitin are both fiber-forming polymers, and as fibers they serve as the load-bearing components of major groups of natural composite tissues—cellulose in many plant-cell walls and chitin in the skeletal materials of many lower animals. Their chemical structures are very similar: cellulose is poly-β(1→4)-d-glucose and chitin is its 2-acetamido derivative (see Fig. 1); not surprisingly, this leads to similar structures and morphologies. The β(1→4) glucan chain is inherently stiff and extended and must be judged ideal for the formation of fibrous structures. Both polymers are naturally crystalline, and their crystal structures have been the subject of X-ray crystallographic studies for over 60 years. From early studies, it was known that both cellulose and chitin could adopt a number of different polymorphic structures. These have different unit cells, but in all cases the chains have extended ribbonlike conformations, with two pyranose residues repeating in approximately 10.3 A. The actual packing of these chains and their intermolecular hydrogen bonding proved more difficult to determine, and it has only been in the last decade that these problems have yielded to X-ray investigations. The central question for cellulose was the polarity of adjacent chains: the unit cells contain sections of two chains that could have the same (parallel) or opposite (antiparallel) sense.
TL;DR: Chitin polymerization is catalyzed by cell-free enzyme complexes from the integument of Trichoplusia larvae and wing tissue of developing Hyalophora cecropia pupae, indicating possible hormonal control and integumental CS activity decreases in starved larvae or those about to pupate.
TL;DR: In this article, the grafting of styrene onto chitin powder and chitosan powder and film initiated by γ-ray irradiation was carried out at 30°C.
Abstract: The graft polymerization of styrene onto chitin powder, and chitosan powder and film initiated by γ-ray irradiation was carried out at 30°C. The graft polymerization was found to proceed predominantly in the presence of water, and the degree of grafting increased with an increase in the radiation dose. From ESR spectroscopy it was noted that the free radicals generated both in chitin and in chitosan were stable enough at ambient temperature. Styrene-grafted chitin and chitosan powders thus obtained showed less swelling in water, and chitosan after graft polymerization was insoluble in dilute acids. Graft polymerization of other vinyl monomers was also studied.
TL;DR: It is suggested that chitin and chitosan, as well as crystalline cellulose, may be suitable as diluents for chewable, sublingual or oral mucosal tablets prepared by direct compression processes.
Abstract: As a part of a series of studies on pharmaceutical applications of chitin and chitosan, the fluidity and compressibility of combined powders of mannitol with chitin and chitosan, as well as the disintegration properties of tablets made from these powders were investigated in comparison with those of crystalline cellulose with mannitol. The fluidity of the combined powders with chitin and chitosan was a little greater than that of the powder with crystalline cellulose. At more than 30% addition of chitin, chitosan or crystalline cellulose, tablets were easily formed. Tablets containing less than 60% chitin or chitosan passed the disintegration test of JP X. It is suggested that chitin and chitosan, as well as crystalline cellulose, may be suitable as diluents for chewable, sublingual or oral mucosal tablets prepared by direct compression processes.
TL;DR: Cell walls of Micrococcus luteus, Escherichia coli, and Bacillus subtilis were degraded by the lysozyme but chitin or cell walls of Staphylococcus aureus were resistant to its activity.
Abstract: 1.
1. Lysozyme isolated from the crystalline style of Mytilus edulis is a true N-acetylmuramylhydrolase (E.C. 3.2.1.17).
2.
2. The enzyme is optimally active at approx pH 7.1, I = 0.011, with a secondary optimum at pH 4.6, I = 0.054.
3.
3. Cell walls of Micrococcus luteus, Escherichia coli, and Bacillus subtilis were degraded by the lysozyme but chitin or cell walls of Staphylococcus aureus were resistant to its activity.
4.
4. Tetra-N-acetyl chitotetraose inhibited enzyme activity more than N-acetylglucosamine, di-N-acetyl chitobiose, tri-N-acetyl chitotriose or penta-N-acetyl chitopentaose.
TL;DR: The 'inhibitor' of chit in synthetase previously isolated from the cytosol of Mucor rouxii was found to be a chitinase, which was much more effective against nascent chitins than against preformed chitIn.
TL;DR: In this paper, the 13C NMR spectra of chitin in lithium thiocyanate and in LiCl/dimethylacetamide solutions were used to characterize regular polymers.
Abstract: The 13C NMR spectra of N-acetyl-D-glucosamine (1) and chitobiose (2), monomer and dimer of chitin, were assigned and used to assign the 13C NMR spectra of chitin in lithium thiocyanate and in LiCl/dimethylacetamide solutions. The dissolution of chitin in formic acid was studied. IR, 13C and 1H NMR spectra show that dissolution occurs by a reaction of formic acid with chitin with the formation of formyl chitin as a statistical derivative of chitin. 13C NMR spectra of diformyl- and diacetylchitin were also assigned to characterize these regular polymers.
TL;DR: Biosynthesis of cell-wall glucans was studied during regeneration of protoplasts from Schizophylhum commune and polyoxin D, an inhibitor of chitin synthase, completely arrested accumulation of alkali-insoluble (1 → 3)-β-glucan.
Abstract: SUMMARY: Biosynthesis of cell-wall glucans was studied during regeneration of protoplasts from Schizophylhum commune. Double-labelling experiments using [14C]glucose and [3H]glucose indicated a larger pool size of precursors for an alkali-insoluble (1 → 3)-β-glucan than for the other cell-wall components, (1 → 3)-α-glucan and chitin. Pulse-chase experiments established the existence of a water-soluble, partly alkali-soluble (1 → 3)-β-glucan as a precursor for the alkali-insoluble wall glucan, containing only (1 → 3)-β-linkages. Polyoxin D, an inhibitor of chitin synthase, completely arrested accumulation of alkali-insoluble (1 → 3)-β-glucan. This antibiotic did not inhibit the synthesis of the water-soluble glucan, but prevented the incorporation of this material into the alkali-insoluble glucan/chitin complex. Cycloheximide added at the start of regeneration prevented the synthesis of the alkali-insoluble (1 → 3)-β-glucan and of the water-soluble glucan precursor, whereas no effect on the formation of the alkali-insoluble glucan was observed when cycloheximide was added 3 h after the onset of the regeneration.
TL;DR: In this article, the dissolution behavior of ground mixtures of griseofulvin with chitin, chitosan and crystalline cellulose was investigated, with a view to an application of Chitin and Chitosans to pharmaceutical preparations.
Abstract: The dissolution step of practically insoluble drugs plays an important role in the drug absorption. In this study, with a view to an application of chitin and chitosan to pharmaceutical preparations, the dissolution behavior of ground mixtures of griseofulvin with chitin and chitosan was investigated. Ground mixtures of griseofulvin with chitin, chitosan and crystalline cellulose were prepared by grinding in a ball mill. The X-ray diffraction patterns and results of differential scanning calorimetry suggested a relative decrease in the size of the crystals of griseofulvin in the ground mixtures. The dissolution rate of griseofulvin from the ground mixtures was significantly greater than that from the physical mixture or from intact griseofulvin powder. The ground mixture with chitosan showed fastest dissolution. These results indicate that chitin and chitosan can improve the dissolution properties of griseofulvin.
TL;DR: Findings suggest that chitin synthesis inhibitors may serve as drugs which specifically block the life cycle of the Entamoeba parasite.
TL;DR: In this paper, the effect of several variables on the adsorption rate of four dyestuffs onto chitin was studied, and a model was proposed enabling the film mass transfer coefficients to be determined.
Abstract: The effect of several variables on the adsorption rate of four dyestuffs onto chitin was studied. A model is proposed enabling the film mass transfer coefficients to be determined. The coefficients were independent of initial dye concentration, chitin mass, chitin particle size, and temperature; a slight dependence with agitation was obtained. The film mass transfer coefficients at 400 rpm were 2.8×10−3, 2.9×10−3, 3.9×10−3, and 0.9×10−3 cm/s for Acid Blue 25, Acid Blue 158, Mordant Yellow 5, and Direct Red 85, respectively.
TL;DR: A chemical method for the quantitative measurement of fungal chitin was used to estimate the level of mold contamination in tomato products and showed a significant correlation between fungal glucosamine content and the Howard mold count.
Abstract: A chemical method for the quantitative measurement of fungal chitin was used to estimate the level of mold contamination in tomato products. The alkaline degradation of chitin results in a polyglucosamine which is measured calorimetrically and the results expressed as μg of fungal glucosamine. Addition of fungal mycelium to tomato products gave recoveries of 97 ± 3% of the expected level of glucosamine. Analysis of various types of tomato products showed a significant correlation (P < 0.01) between fungal glucosamine content and the Howard mold count.
TL;DR: A method of short-term culturing is described for the analysis of chitin and glyconjugates biosynthesis by epidermal tissue of Triatoma infestans.
TL;DR: Values of the dispersive and nondispersive components of the surface tension that are very close to those obtained for glutaraldehyde-treated umbilical cord vessels are found, and all of the acylated Chitin surfaces show longer clotting times than the original chitin surface.
Abstract: Various acylated chitins, including formyl, acetyl, propionyl, butyryl, caproyl, capryl, lauroyl, and benzoylchitin, were evaluated as materials for blood contact surfaces by means of contact angle and blood-clotting time measurements. Critical surface tensions of acylated chitins varied within the range of 20-30 dyn cm-1 and were dependent on the length of the acyl side chains. Furthermore, the dispersion and nondispersion components of the surface tension show remarkable differences which are dependent on the type of acyl group attached to chitin. The chitin derivative with 2.0 acetyl groups per N-acetylglucosamine residue gave values of the dispersive and nondispersive components of the surface tension that are very close to those obtained for glutaraldehyde-treated umbilical cord vessels. All of the acylated chitin surfaces show longer clotting times than the original chitin surface.