Showing papers on "Chitin published in 1981"
TL;DR: Research on chitin as a marine resource is pointing to novel applications for this cellulose-like biopolymer, and new methods for preparing the bioactive alkyl glycoside of N-acetyl-D-glucosamine and microcrystalline Chitin have encouraged their use as promoters for growth of bifidobacteria and as an aid in digestion of high-lactose cheese whey by domestic animals.
Abstract: Research on chitin as a marine resource is pointing to novel applications for this cellulose-like biopolymer. Discovery of nondegrading solvent systems has permitted the spinning of filaments, for example, for use as surgical sutures. New methods for preparing the bioactive alkyl glycoside of N-acetyl-D-glucosamine (the monomer unit of chitin) and a microcrystalline chitin has encouraged their use as promoters for growth of bifidobacteria and as an aid in digestion of high-lactose cheese whey by domestic animals. Chitin-protein complexes of several crustacean species show great variability in ratios of chitin to covalently bound protein and in residual protein in the "purified" chitins.
340 citations
TL;DR: Chitin and chitosan could be useful vehicles for the sustained release of drugs and used as model drugs in this evaluation.
Abstract: The suitability of chitin and chitosan for use as vehicles for the sustained release of drugs was examined. Indomethacin and papaverine hydrochloride were used as model drugs in this evaluation. Sustained release of the drugs from the dried gels was obtained. Drugs dispersed in the chitosan gels were released at a constant rate (zero order). Chitin and chitosan could be useful vehicles for the sustained release of drugs.
209 citations
TL;DR: Both residues were needed for cleavage, and polymers containing equal proportions of acetylated and non-acetylated sugars were optimal for chitosanase activity, which strongly indicated that P. islandicum chitOSanase cleaved chitan between N- acetylglucosamine and glucosamine.
Abstract: Penicillium islandicum produced an inducible extracellular chitosanase when grown on chitosan. Large-scale production of the enzyme was obtained using Rhizopus rhizopodiformis hyphae as substrate. Chitosanase was purified 38-fold to homogeneity by ammonium sulphate fractionation and sequential chromatography on DEAE-Biogel A, Biogel P60 and hydroxyl-apatite. Crude enzyme was unstable at 370C, but was stabilized by 1·0 mm-Ca2+. The pH optimum for activity was broad and dependent on the solubility of the chitosan substrate. Various physical and chemical properties of the purified enzyme were determined.
Penicillium islandicum chitosanase cleaved chitosan in an endo-splitting manner with maximal activity on polymers of 30 to 60% acetylation. No activity was found on chitin (100% acetylated chitosan) or trimers and tetramers of N-acetylglucosamine. The latter two oligomers and all small oligomers of glucosamine inhibited the activity of chitosanase on 30% acetylated chitosan. The pentamer of N-acetylglucosamine and glucosamine oligomers were slowly cleaved by the enzyme. Analysis of the reaction products from 30% acetylated chitosan indicated that the major oligomeric product was a trimer; with 60% acetylated chitosan as substrate a dimer was also found. The new terminal reducing groups produced by chitosanase hydrolysis of 30% acetylated chitosan were reduced by sodium boro[3H]hydride. The new end residues were found to be N-acetylglucosamine. The analyses strongly indicated that P. islandicum chitosanase cleaved chitosan between N-acetylglucosamine and glucosamine. Both residues were needed for cleavage, and polymers containing equal proportions of acetylated and non-acetylated sugars were optimal for chitosanase activity. The products of reaction depended on the degree of acetylation of the polymer.
131 citations
TL;DR: In Saccharomyces cerevisiae, Neurospora crassa, Aspergillus nidulans and Coprinus cinereus most of the alkali-insoluble (13)-β-D/(16)- β-D-glucan of the wall can be extracted with dimethyl sulphoxide, indicating that it is covalently linked to chitin in the wall.
Abstract: In Saccharomyces cerevisiae, Neurospora crassa, Aspergillus nidulans and Coprinus cinereus most of the alkali-insoluble (13)-β-D/(16)-β-D-glucan of the wall can be extracted with dimethyl sulphoxide. The same fraction, and in Saccharomyces cerevisiae a small additional fraction, can be extracted by a destructive procedure involving 40% NaOH at 100 C. The small fraction of the glucan which resists this treatment becomes soluble after a subsequent treatment with HNO2 indicating that it is covalently linked to chitin in the wall. In contrast, in Schizophyllum commune and Agaricus bisporus, nearly all the (1 3)-β-D-/(1 6)-β-D-glucan appears to be held insoluble by linkage to chitin.
103 citations
TL;DR: Several important groups of fungicides and insecticides are specific inhibitors of chitin synthesis in a Phycomyces enzyme system and in insect organ cultures, and the recently discovered benzoylphenylurea insect pesticides are apparently not direct-acting chit in synthetase inhibitors.
Abstract: Several important groups of fungicides and insecticides are specific inhibitors of chitin synthesis in a Phycomyces enzyme system and in insect organ cultures. The recently discovered benzoylphenylurea insecticides, which prevent chitin synthesis in insect tissues, are apparently not direct-acting chitin synthetase inhibitors. These insecticides may prevent insect chitin synthesis by interfering with the proteolytic activation of the chitin synthetase zymogen.
99 citations
TL;DR: The results are consistent with IMR-1E1 containing a regulatory mutation which increased production of the components of the chitinolytic enzyme system and/or with IMG1E2 containing a tandem duplication of theChitinase genes.
Abstract: Genetic modification of Serratia marcescens QMB1466 was undertaken to isolated mutants which produce increased levels of chitinolytic activity. After mutagenesis with ultraviolet light, ethyl methane sulfonate or N-methyl-N'-nitro-N-nitrosoguanidine, 19,940 colonies were screened for production of enlarged zones of clearing (indicative of chitinase activity) on chitin-containing agar plates. Forty-four chitinase high producers were tested further in shake flask cultures. Mutant IMR-1E1 was isolated which, depending on medium composition, produced two to three times more than the wild type of the other components of the chitinolytic enzyme system--a factor involved in the hydrolysis of crystalline chitin and chitobiase. After induction by chitin, endochitinase and chitobiase activity appeared at similar times for both IMR-1E1 and QMB1466, suggesting possible coordinate control of these enzymes. The results are consistent with IMR-1E1 containing a regulatory mutation which increased production of the components of the chitinolytic enzyme system and/or with IMR-1E1 containing a tandem duplication of the chitinase genes. The high rate of reversion of IMR-1E1 to decreased levels of chitinase production suggests that the overproduction of chitinase by IMR-1E1 is due to a tandem gene duplication.
98 citations
TL;DR: The sucker disc of Octopus is shown to contain chitin by chemical and physical methods and comparisons are made between the amino acid compositions of these and related chitIn-protein complexes in terms of parameters such as polar content, hydrophobicity and conformational potential.
Abstract: 1 1 Chitin-protein complexes from a variety of cephalopod tissues show a surprisingly wide range of composition both in terms of the chitin-protein ratio and the composition of the protein 2 2 Comparisons are made between the amino acid compositions of these and related chitin-protein complexes in terms of parameters such as polar content, hydrophobicity and conformational potential 3 3 The sucker disc of Octopus , a structure not previously identified as chitinous, is shown to contain chitin by chemical and physical methods
93 citations
TL;DR: The conversion of the enzymatic hydrolysate of shellfish chitin waste to single‐cell protein was investigated as part of a comprehensive waste treatment program and the Yeast Pichia Kudriavzevii was selected for study.
Abstract: The conversion of the enzymatic hydrolysate of shellfish chitin waste to single-cell protein was investigated as part of a comprehensive waste treatment program. Forty-two yeasts were screened for ability to assimilate the monomer of chitin, N-acetylglucosamine, which has been shown to be the sole product of enzymatic hydrolysis of chitin. The Yeast Pichia Kudriavzevii was selected for study, based on ability to grow at high temperature (37°C and above), low pH (4.0 ± 0.5), and in a nutritionally simple medium. Growth rates of P. kudriavzevii were similar on N-acetylglucosamine and on the chitin hydrolysate. Dependencies of specific growth rate on temperature, pH, medium composition, and oxygen tension were studied. The variations of yield, protein content, and total nucleic acid content with the specific growth rate were evaluated. The amino acid distribution of the protein of P. kudriavzevii was obtained.
88 citations
TL;DR: Chemical analyses reveal that ghosts consist largely, and perhaps exclusively, of chitin and protein, and indicates that the accompanying protein is exposed and therefore accessible to several types of proteolytic enzymes.
80 citations
TL;DR: The influence of pH on chitin hydrolysis by Streptomycetes from a range of acidic and neutral soils was studied in vitro in an acid soil and Acidophiles were involved in the decomposition process and the resulting ammonification led subsequently to activity of neutrophiles.
Abstract: The influence of pH on chitin hydrolysis by Streptomycetes from a range of acidic and neutral soils was studied in vitro in an acid soil. On the basis of activity ranges and optima for chitin hydrolysis, acidophilic, acidoduric and neutrophilic categories of Streptomycetes were dis- tinguished; these categories were broadly related to the pH requirements for growth. Responses of Streptomycetes to chitin amendment of acidic organic and mineral horizons of a pine forest soil were studied. Acidophiles were involved in the decomposition process and the resulting ammonification led subsequently to activity of neutrophiles. This succession was particularly marked in the poorly buffered mineral horizon. Similar, but smaller, responses occurred when the horizons were amended with mycelium from basidiomycete sporocarps. The role of streptomycetes in decomposition of fungal chitin in acidic litters and soils is discussed.
71 citations
01 Jan 1981
TL;DR: The polysaccharide chitin, which may be considered the equivalent of cellulose in the plant kingdom, is of great importance in fungal growth and physiology and constitutes a very useful model for the study of morphogenetic processes.
Abstract: Chitin is ans ubiquitous component of fungal cell walls. Only a few classes of fungi, such as the Oomycetes and Trichomycetes (Bartnicki-Garcia 1968) appear to lack chitin. Even in species of the Saccharomycetaceae, which were classified as devoid of chitin by Bartnicki-Garcia, small amounts of the polysaccharide are found in the cell wall, with a preferential localization in the septum (Cabib et al. 1974). Because of its function in the generation and maintenance of cell shape and in the formation of septa, chitin is of great importance in fungal growth and physiology. For the same reasons, it constitutes a very useful model for the study of morphogenetic processes. Hence the interest of many investigators in this polysaccharide, which may be considered the equivalent, for fungi, of cellulose in the plant kingdom.
TL;DR: A microsomal preparation from larval stages of the brine shrimp Artemia salina was found to catalyze the transfer of N- acetyl-D-glucosamine from UDP-N-acetylglucOSamine to an endogenous acceptor, which was identified as chitin by its resistance to extraction with alkali and high concentrations of urea.
TL;DR: Chitin synthase activity in total membrane fractions from two polyenes-resistant, ergosterol-deficient mutants of Candida albicans was significantly higher in comparison to the parental polyene-sensitive strain.
Abstract: Chitin synthase activity in total membrane fractions from two polyene-resistant, ergosterol-deficient mutants ofCandida albicans was significantly higher in comparison to the parental polyene-sensitive strain The zymogen component from membrane preparations of stationaryphase cells of ergosterol mutants was more susceptible to trypsin digestion than those from the parental polyene-sensitive strain Mechanisms that might explain the effect of changes in membrane composition in the mutant strains on chitin synthase activity are discussed
TL;DR: In this paper, the adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water.
Abstract: The adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid during the first 10 min and was affected by pH of the solution, temperature, granule radius and the co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate.
TL;DR: An alkali-insoluble core material was isolated from the fruit bodies of Lentinus edodes after exhaustive extraction with 24% NaOH at 5 degrees C and methylation analysis has shown that the glucan part of the core material has a highly branched structure with 1,6 and 1,3 linkages in a molar ratio of 2 : 1.
Abstract: An alkali-insoluble core material was isolated from the fruit bodies of Lentinus edodes after exhaustive extraction with 24% NaOH at 5 degrees C. This material consists mainly of glucan which is closely associated with chitin. Methylation analysis has shown that the glucan part of the core material (skeletal glucan) has a highly branched structure with 1,6 and 1,3 linkages in a molar ratio of 2 : 1. Stepwise enzymatic hydrolysis with basidiomycete sp. QM 806 beta-1,3-glucanase has indicated the heterogeneity of the skeletal glucan. The outer part of the skeletal glucan seems to be composed mainly of beta-1,3 and beta-1,6 glucoside linkages and has a close structural similarity to lentinan, a water-soluble beta-glucan from L. edodes. The middle part of the skeletal glucan appears to be composed mainly of beta-1,6 glucoside linkages. The innermost part of the skeletal glucan is a highly branched glucan with beta-1,6 and beta-1,3 linkages. Probably, it is associated with chitin and a small amount of amino acid polymer.
TL;DR: Results obtained with an in vitro system for the study of chitinase give results consistent with a processive mechanism for molting fluid chit inase, i.e., data are given demonstrating that molbing fluid ch itinase continues to act on the same chitIn particle(s) with which it initially associates rather than diffusing freely from substrate particle to substrate particle, and the product of its action appears to be a monosaccharide rather than a mixture of olig
TL;DR: The method, adapted from one described for assaying plant material for fungal content, is based on estimating soluble chitosan derivatives and is not affected by the presence of nonchitinous cuticular components.
TL;DR: The covalently bound chitin-protein mucopolysaccharides of several species of marine invertebrates have been fractionated by alkali and acid treatments similar to those used in the normal isolation of chitins, with marked species variation in their identity and content.
Abstract: 1. 1. The covalently bound chitin-protein mucopolysaccharides of several species of marine invertebrates have been fractionated by alkali and acid treatments similar to those used in the normal isolation of chitin. 2. 2. These chitin isolates and even the further-deproteinated chitins all contained small amounts of residual amino acids, with marked species variation in their identity and content. 3. 3. Aspartic acid, serine and glycine were most prevalent (aspartic acid persistent) and could be involved in the covalent linkage between chitin and protein.
TL;DR: The effect of various organisms on the decompositon of chitin in a gnotobiotic soil system was investigated and net mineralization of ammonium was greatest in the Chitin-ainended microcosms containing the fungus and the actinomycete.
Abstract: The effect of various organisms on the decompositon of chitin in a gnotobiotic soil system was investigated. Chitin decomposers were isolated from the short grass prairie in Colorado and selected by their ability to use chitin as a source of both C and N. Three bacteria, a fungus, and an actinomycete were grown for 45 days in sterile chitin amended (3 mg g−1 chitin-C) and unamended soil microcosms. Net mineralization of ammonium was greatest in the chitin-ainended microcosms. The greatest increases in N mineralization occurred in chitin-amended microcosms containing the fungus and the actinomycete. A second series of sterile soil microcosms amended with chitin (3 mg g−1 chitin-C) were inoculated with decomposers, a fungus and a bacterium, and a nematode and an amoeba (bacteriophagic grazers) in various combinations. Bacterial and grazer populations, NH4+ CO2 evolution, and residual chitin were measured periodically for 80 days. Bacterial grazing reduced bacterial populations, increased N mineralization, but had no effect on the decomposition of chitin.
TL;DR: The hydrolysis of chitin by Serratia marcescens chit inase was studied as part of an overall project to develop a chitIn waste treatment bioconversion scheme.
Abstract: The hydrolysis of chitin by Serratia marcescens chitinase was studied as part of ar overall project to develop a chitin waste treatment bioconversion scheme. Hydrolyses were conducted with automatic pH control in stirred flasks. Parameters varied were temperature, enzyme activity, and chitin particle size and concentration. A temperature of 30°C is suitable. Hydrolysis increases with increasing enzyme activity and chitin slurry concentration, and with decreasing particle size.
TL;DR: It was found that invertase and amyloglucosidase achieved high activity after immobilization on chitin obtained at not too rigorous conditions of deproteinization, however, the activity of immobilized α‐amylase and diastase increased significantly with the increase in concentration of KOH used for dep Proteinization.
Abstract: The suitability of krill chitin, prepared by using different concentrations of KOH and HCI for deproteinization and demineralization, respectively, was investigated. The activity of enzymes immobilized on such supports depends on the degree of deproteinization of chitin, availability of amino groups, content of minerals, mesh size, structure of the surface, and conformation of the chitin molecules. It was found that invertase and amyloglucosidase achieved high activity after immobilization on chitin obtained at not too rigorous conditions of deproteinization. However, the activity of immobilized α-amylase and diastase increased significantly with the increase in concentration of KOH used for deproteinization. High content of minerals and proteins in chitin preparation causes a loss of immobilized enzyme activity.
TL;DR: In this paper, a quick and sensitive chitin assay has been developed which will provide a useful adjunct to other methods for the quantitative assessment of fungal attack of wood, including wood preservatives in field trial situations.
Abstract: A quick and sensitive chitin assay has been developed which will provide a useful adjunct to other methods for the quantitative assessment of fungal attack of wood. Various parameters of the general technique were studied, including the Optimum time for hydrolysis of chitin, the effects of various amino-acids on the procedure, and the effect of CCA salts on qualitative and quantitative determinations. Further, the chitin contents (% w/w) of selected fungi grown in lownitrogen medium were investigated. The technique was compared with other described assay procedures for the estimation of soft-rot attack of wooden poles. The chitin assay could be especially useful for the evaluation of wood preservatives in field trial situations.
TL;DR: Comparison of the synthesis of chitin in epidermis of G. mellonella with previously published ecdysone titres, indicated that chitIn production in vivo is preceded by an elevated ecdYSone titre.
TL;DR: By simple adsorption or covalent binding, enzymes were immobilized on chitin isolated from the shells of edible shellfish as discussed by the authors, and the best results were obtained by immoblizing diastase on krill chitIN by adsorment at pH 6.7 and an ionic strength of 0.05.
Abstract: By simple adsorption or covalent binding, enzymes were immobilized on chitin isolated from the shells of edible shellfish. It is reported that the best results were obtained by immoblizing diastase on krill chitin by adsorption at pH 6.7 and an ionic strength of 0.05.
TL;DR: The components and structure of the cell wall of Rhizopus delemar were investigated using purified lytic enzymes, protease and chitosanase from Bacillus R-4 and Chitinase II from Streptomyces orientalis and when used together, a complete lysis was achieved by cooperative action.
Abstract: The components and structure of the cell wall of Rhizopus delemar were investigated using purified lytic enzymes, protease and chitosanase from Bacillus R-4 and chitinase II from Streptomyces orientalis. When these enzymes were used individually they only partially lysed the cell wall, but when allowed to react on the cell wall together, a complete lysis was achieved by cooperative action. These modes of action on the cell wall and the chemical and morphological data suggested that the cell wall structure was different in Rhizopus delemar of Zygomycetes from filamentous fungi of Euascomycetes and that its wall structure might be composed mainly of chitin fibers cemented by chitosan and protein or peptides scattered in a mosaic manner.
TL;DR: The results indicate that Mucor yeasts have a relatively low differential rate of chitin-plus-chitosan synthesis and that mycelial cells have a threefold-elevated differential rate, and strengthen the idea that cyclic adenosine 3',5'-monophosphate plays an important role in dimorphism in Mucors.
Abstract: The in vivo differential rates of chitin-plus-chitosan biosynthesis in Mucor racemosus were determined under a variety of conditions, leading to yeast cell or mycelial morphology Chitin-chitosan was determined as hot NaOH-insoluble radioactivity derived from N-acetyl-D-[1-3H]glucosamine in the medium Control experiments demonstrated that the labeled material possessed the properties of chitin-plus-chitosan Our results indicate that Mucor yeasts have a relatively low differential rate of chitin-plus-chitosan synthesis and that mycelial cells have a threefold-elevated differential rate Treatment of aerobic cells with exogenous N6, O2-dibutyryl cyclic adenosine 3',5'-monophosphate, an agent which induces yeast cell morphology, also results in a lowered rate of chitin-plus-chitosan synthesis Control experiments eliminated the possibility that the observed rate changes were due to changes in endogenous pool size, uptake of exogenous N-acetyl-p-[1-3H]glucosamine, or alterations in growth rate Therefore, the changes are seemingly linked to morphogenesis These results strengthen the idea that cyclic adenosine 3',5'-monophosphate plays an important role in dimorphism in Mucor In addition, pulse-chase experiments suggest that considerable modification of newly synthesized chitin plus chitosan in both yeast cells and mycelia occurs in vivo
TL;DR: When gamma particles isolated from the aquatic fungus, Blastocladiella emersonii, were incubated in a supernatant derived from a homogenate of zoospores previously triggered to encyst with 50 mM KCl, they exhibited a three-fold increase in chitin synthetase activity and produced chitosome-like vesicles.
Abstract: When gamma particles isolated from the aquatic fungus, Blastocladiella emersonii, were incubated in a supernatant derived from a homogenate of zoospores previously triggered to encyst with 50 mM KCl, they exhibited a three-fold increase in chitin synthetase activity and produced chitosome-like vesicles. Passage of such vesicles through a linear sucrose gradient resulted in a symmetrical distribution of chitin synthetase activity over a broad portion of the gradient, and the specific activity of the peak fraction was seven times greater than that of the gamma particles. After isopycnic sucrose gradient centrifugation, chitin synthetase activity occurred in a band of particles with a peak buoyant density of 1.18 g/cm3. Ultrastructural examination of negatively stained samples from the peak fraction revealed spheroidal, chitosome-like particles 70–120 nm in diameter. Suspension of these particles produced chitin microfibrils when incubated with uridine diphosphate N-acetylglucosamine, the substrate for chitin synthetase.
TL;DR: Two chitin synthesising systems in Tetranychus urticae are described: one chitosomal system located in the oocytes where spatial and temporal distances are large, and one membrane bound system Located in the hypodermis.
Abstract: Two chitin synthesising systems in Tetranychus urticae are described: one chitosomal system located in the oocytes where spatial and temporal distances are large, and one membrane bound system located in the hypodermis. Similarity of mechanisms of chitin synthesis in animals and plants is suggested.
TL;DR: During culture of Rhodotorula glutinis the fall in pH from 4.5 to 2 stimulates the synthesis of chitin and there is no proportional value between the chit in content fall and that of total hexosamines.