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1.
Two types of chitosan oligosaccharides (COS), COS I (1-kDa < MW < 3-kDa) and COS II (3-kDa < MW < 5-kDa), were tested for antimutagenic activities against chemical mutagens using Umu gene expression, Ames, and Bacillus subtilis Rec mutagenicity tests. At the highest chitosan oligosaccharide dose (1 mg) tested, mutagenic activity of indirect-acting mutagen was inhibited by 50% in the Umu gene expression system and in the Ames test. Chitosan oligosaccharide (0.01, 0.1 and 1 mg) also suppressed 4-nitroquinoline-N-oxide (NQO)-induced mutagenicity in the B. subtilis Rec assay.  相似文献   

2.
The crude fractions of chitooligosaccharides (COS) and low-molar-mass chitosans (LMWC) were prepared by enzyme hydrolysis of chitosan (CS). Specific growth rate of B. adolescentis, B. bifidum, B. breve, B. catenulatum, B. infantis and B. longum ssp. longum was determined in the presence of 0.025 and 0.5 % COS (<5 kDa), LMWC (5–10 kDa), and 0.025, 0.1 and 0.5 % of CS, chitosan succinate and chitosan glutamate in vitro. Minimum inhibitory concentrations (MIC; assayed by colony counting on TPY agar plates) of COS-LMWC and CS ranged from 0.025 % to 0.75 % of CS-LMWC. The growth of all bifidobacterial strains in the presence of chitosan, its derivatives and LMWC decreased at a concentration of 0.025 %; the bacterial growth was completely inhibited at a concentration of 0.5 %. COS did not show any inhibitory effect, an increased growth rate was even observed in the case of B. bifidum, B. catenulatum and B. infantis.  相似文献   

3.
Dietary chitosans with different molecular weight Mw and the degree of deacetylation DDA (high molecular weight chitosan HCS with Mw 7.60 × 105 and DDA 85.5%, middle molecular weight chitosan MCS with Mw 3.27 × 104 and DDA 85.2%, chito-oligomer COS with Mw 0.99 × 103 and DDA 85.7% and water-soluble chitosan WSC with Mw 3.91 × 104 and DDA 52.6%) were used at the 1.05% level to feed mice for 90 days. Afterwards no pathological symptoms, clinical signs or deaths were observed. The body weight of mice in chitosan group and control group showed no significant difference. Although HCS, COS and WSC had no significant effect on the level of Fe, Zn and Cu in the tested mice’s liver, spleen, heart and kidney, MCS significantly increased the level of Fe, Zn and Cu in liver. Therefore dietary ingestion of chitosan did not depress the level of Fe, Zn and Cu in mice.  相似文献   

4.
Chitooligosaccharides (COS), depolymerized products of chitosan, has received considerable attention as bioactive material due to their biocompatible, biodegradable, non-toxic and non-allergenic natures. In this study, COS of four different molecular weight ranges (<1, 1-3, 3-5 and 5-10 kDa) were investigated for their abilities to modulate inflammatory mediators in lipopolysaccharides (LPS)-stimulated BV2 microglia. At the concentration of 500 μg/ml, COS attenuate the productions of nitric oxide (NO) and prostaglandin E2 (PGE2) by inhibiting inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions. Furthermore, the release and expression levels of inflammatory cytokines; including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were also attenuated by COS. Notably, the inhibitory activity of COS depends significantly on its molecular weight, with lower molecular weight showed higher activity. In addition, the suppressive effects on the phosphorylation of JNK and p38 mitogen-activated protein kinase (MAPK) by COS were confirmed. These results indicate that COS could be used as an inhibitor in regulating microglial inflammatory responses. Moreover, COS may assist therapeutic treatment of neurodegenerative diseases which accompanied with microglial activation.  相似文献   

5.
Antibacterial effect of chitooligosaccharides (COS) and low molar mass chitosans (LMWC) is considered as one of the most important characteristics of chitosan (CS) hydrolysates. Here, we show the in vitro effect of different COS, LMWC, and CS on representative anaerobic bacteria isolated from human colon as a possibility of targeting modification of colonic microflora composition by supplementation of dietary CS products by humans. Specific growth rate of seven selected nonpathogenic anaerobic bacterial strains (Clostridium paraputrificum, Clostridium beijerinckii, Roseburia intestinalis, Bacteroides vulgatus, Bacteriodes thetaiotaomicron, Faecalibacterium prausnitzii and Blautia coccoides) was determined in the presence of 0.25 and 0.5% COS (2, 3, and 6 kDa), 0.025 and 0.05% of LMWC (10 and 16 kDa), and 0.025 and 0.1% of CS in vitro. The growth rate decreased in all strains in the presence of COS and LMWC in higher concentrations in comparison to control incubations. A relatively higher resistance to CS hydrolyzates was detected in R. intestinalis and F. prausnitzii, and more susceptible were bacteria belonging to Bacteoides sp. and Clostridium sp. The antimicrobial activity, minimum inhibitory concentrations (MIC), and minimal bactericidal concentrations (MBC) were determined. The antimicrobial activity increased with the degree of polymerization (DP). MIC ranged from 0.25 to 4.5% in dependence on bacterial strain and DP of CS/LMWC. MBC also decreased with DP. The most effective antimicrobial action was detected in LMWC with 16 kDa and CS. Weak antimicrobial activity was found in COS with small molecules (2 and 3 kDa).  相似文献   

6.
为了探讨拟南芥O-岩藻糖基转移酶(SPINDLY)在病原体相关分子模式诱导抗性中的作用,该研究以SPINDLY缺失拟南芥突变体spy-3为实验材料,从叶片表型、病情指数、病菌定殖量以及丁香假单胞菌(Pst DC3000)关键基因的表达水平等指标,系统考察了SPINDLY在壳寡糖诱导拟南芥抗Pst DC3000中的功能。结果显示:(1)spy-3突变体比野生型更易被Pst DC3000侵染。(2)与病菌侵染组相比,壳寡糖预处理明显缓解植株叶片黄化现象,显著降低Pst DC3000的定殖量。(3)壳寡糖预处理的spy-3植株中水杨酸和茉莉酸途径相关基因的表达量及水杨酸和茉莉酸含量均较病菌侵染组明显升高。(4)壳寡糖在spy-3中的诱抗效果与野生型相比无明显差别。研究表明,SPINDLY在植物先天免疫过程发挥重要作用,但并不影响壳寡糖的诱导抗性。  相似文献   

7.
Bacillus licheniformis MB-2, isolated from a hot spring water in Manado, Indonesia, secreted a unique chitosanase. Media consisted of 0.24% chitosan, 0.25% casiton, 1% MgSO4, 1.4% K2HPO4, 0.02% CaCl2·2H2O, 0.002% FeSO4·7H2O (w/v) was used for enzyme production. Purification of the enzyme through the hydrophobic interaction chromatography system (butyl Sepharose 4 FF) resulted in two major active fractions; the F2 fraction was shown as a single band at both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zymogram analysis with apparent molecular mass of 75 kDa. The enzyme worked best at 70°C and pH between 6.0 and 7.0. When incubated at 70, 80, and 90°C, the t1/2 values were 26.56, 18.44, and 16.74 min, respectively with the k constant being at 0.026, 0.037, and 0.04/min. When heated at 90°C, the enzyme retained its activity up to 8 h in the presence of 1mM MnCl2. The enzyme's activity was unaffected by the presence of 1 M NaCl and 6 M urea but was decreased by 2 M of guanidine hydrochloride. Albeit the enzyme did not degrade colloidal and glycol chitin, it hydrolyzed glycol chitosan up to 0.8% and colloidal chitosan up to 11%. The 85% deacetylated (DDA) soluble chitosan was the most susceptible to this enzyme, followed by 90% and 100% DDA chitosan. The K m app values of the 85, 90, and 100% DDA soluble chitosans were found as 0.23, 0.24, and 0.58 mg/mL, whereas the Vmax values were 843, 668, and 261 U/mg, respectively. The hydrolysis products of F2 chitosanase at 24 h incubation (70°C) were pentasaccharide (GlcN)5 and hexasaccharide (GlcN)6. The prelimiaary test showed inhibitory effect of chitooligosaccharides resulted from enzymatic degradation toward Pseudomonas aeruginosa, Salmonella typhimurium. Listeria monocytogenes, Bacillus cereus, Escherichia coli, and Staphylococcus aureus.  相似文献   

8.
Chitooligosaccharides (COS) are partially hydrolyzed compounds derived from chitosan that exhibit a number of biological activities, including antitumor, antibacterial and antifungal properties. In this work, we examined the cytotoxicity of pure COS and oligomers A, B and C (solutions composed of different amounts of COS) produced by enzymatic hydrolysis using a crude enzyme extract produced by the fungus Metarhrizium anisopliae. The antiproliferative effect of these molecules was analyzed using tumor cell lines (HepG2 and HeLa cells) and in a normal cell line (3T3). The antioxidant activity was analyzed in several in vitro experiments. Glucosamine showed higher toxicity (approximately 92%) to all cell lines studied. However, the oligomers obtained after hydrolysis demonstrated no toxic effects on the normal cells (3T3). Furthermore, we showed that a small amount of other COS can decrease the cytotoxic effect of glucosamine against 3T3 cells, indicating that glucosamine could be used as an antitumor drug in the presence of other COS. In addition, different effects were found in antiproliferative assays, which depended on the COS composition in the oligomers (A, B and C), showing that a combination of them may be essential for developing antineoplastic drugs. Superoxide anion scavenging was the main antioxidant activity demonstrated by the COS and oligomers. This activity was also dependent on the oligomer composition of the chitosan hydrolysates. Further work will identify the ideal proportions of COS and glucosamine for maximizing the effects of these biological activities.  相似文献   

9.
A chitosanolytic enzyme was purified from Enterobacter sp. G-1 by fractionation of 30% saturation with ammonium sulfate, isoelectric focusing, and Sephadex G-100 gel chromatography. The purified enzyme. showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis, and the molecular mass was estimated to be 50 kDa. The enzyme degraded N-acetyl-chitooligosaccharides, glycol chitin, colloidal chitin, and colloidal chitosan (about 80% deacetylated), but did not degrade chitooligosaccharides, colloidal chitosan (100% deacetylated), or Micrococcus lysodeikticus cell walls. It hydrolyzed GlcNAc4–6 and colloidal chitin to GlcNAc2, finally. The main cleavage site with GlcNAc3–6 was the second linkage from the non-reducing end, based on the pattern of pNp-GlcNAc2–5. Colloidal chitosan was hydrolyzed to GlcNAc2 and to similar partially N-acetylated chitooligosaccharides.  相似文献   

10.
The advantage of usingStreptomyces griseus HUT 6037 in the production of chitinase or chitosanase is that the organism is capable of hydrolyzing amorphous or crystal-line chitin and chitosan according to the type of the substrate used. We investigated the effects of the enzyme induction time and chitin sources, CM-chitosan and deacetylated chitosan (degree of deacetylation 75–99%), on production of chitosanase. We found that this strain accumulated chitosanase when cells were grown in the culture medium containing chitosanaceous substrates instead of chitinaceous substrates. The highest chitosanase activity was obtained at 4 days of cultivation with 99% deacetylated chitosan. Soluble chitosan (53% deacetylated chitosan) was found to induce chitinase as well as chitosanase. The specific activities of chitinase and chitosanase were 0.91 and 1.33 U/mg protein at 3 and 5 days, respectively. From the study of the enzymatic digestibility of various degrees of deacetylated chitosan, it was found that (GlcN)3, (GlcN)4 and (GlcN)5 were produced during the enzymatic hydrolysis reaction. The results of this study suggested that the sugar composition of (GlcN)3 was homogeneous and those of (GlcN)4 and (GlcN)5 were heterogeneous.  相似文献   

11.
The aim of this study was to investigate whether supplementation with chitosan (COS) could reduce diarrhea and to explore how COS alleviates intestinal inflammation in weaned pigs. Thirty pigs (Duroc×Landrace×Yorkshire, initial BW of 5.65±0.27) weaned at age 21 d were challenged with enterotoxigenic Escherichia coli during a preliminary trial period, and then divided into three treatment groups. Pigs in individual pens were fed a corn-soybean meal diet, that contained either 0 (control), 50 mg/kg chlortetracycline, or 300 mg/kg COS for 21 days. The post-weaning diarrhea frequency, calprotectin levels and TLR4 protein expression were decreased (P<0.05) in both the COS and chlortetracycline groups compared with control. Simultaneously, supplemental COS and chlortetracycline had no effect on the mRNA expression of TNF-α in the jejunal mucosa, or on the concentrations of IL-1β, IL-6 and TNF-α in serum. However, COS supplementation improved (P<0.05) the mRNA expression of IL-1β and IL-6 in the jejunal mucosa. The results indicate that supplementation with COS at 300 mg/kg was effective for alleviating intestinal inflammation and enhancing the cell-mediated immune response. As feed additives, chitosan and chlortetracycline may influence different mechanisms for alleviating inflammation in piglets.  相似文献   

12.
The activation of mast cells by immunoglobulin E-mediated stimuli is considered as a central event in allergic responses. In this regard, chitosan oligosaccharides (COS) of two different molecular weight ranges (1–3 kDa and 3–5 kDa) were investigated for their capabilities against the activation of RBL-2H3 mast cell sensitized with dinitrophenyl-specific immunoglobulin E antibody and stimulated by antigen dinitrophenyl-bovine serum albumin. It was found that COS significantly inhibited RBL-2H3 cell degranulation via attenuating the releases of histamine and β-hexosaminidase. Moreover, the inhibitory activity of COS was accompanied by a reduction in intracellular Ca2+ elevation. Notably, the expression of immunoglobulin Fc epsilon receptor I (Fc?RI) in RBL-2H3 cells was down-regulated by COS treatment in a dose-dependent manner. The suppressive effect of COS on RBL-2H3 cell activation suggested that COS may be potential candidates of novel inhibitors against allergic reactions.  相似文献   

13.
An extracellular 45 kDa endochitosanase was purified and characterized from the culture supernatant of Bacillus sp. P16. The purified enzyme showed an optimum pH of 5.5 and optimum temperature of 60°C, and was stable between pH 4.5-10.0 and under 50°C. The K m and V max were measured with a chitosan of a D.A. of 20.2% as 0.52 mg/ml and 7.71×10?6 mol/sec/mg protein, respectively. The enzyme did not degrade chitin, cellulose, or starch. The chitosanase digested partially N-acetylated chitosans, with maximum activity for 15-30% and lesser activity for 0-15% acetylated chitosan. The chitosanase rapidly reduced the viscosity of chitosan solutions at a very early stage of reaction, suggesting the endotype of cleavage in polymeric chitosan chains. The chitosanase hydrolyzed (GlcN)7 in an endo-splitting manner producing a mixture of (GlcN)2-5. Time course studies showed a decrease in the rate of substrate degradation from (GlcN)7 to (GlcN)6 to (GlcN)5, as indicated by the apparent first order rate constants, k 1 values, of 4.98×10?4, 2.3×10?4, and 9.3×10?6 sec?1, respectively. The enzyme hardly catalyzed degradation of chitooligomers smaller than the pentamer.  相似文献   

14.
Khan  W.M.  Prithiviraj  B.  Smith  D.L. 《Photosynthetica》2002,40(4):621-624
On the first day after foliar application, chitosan pentamer (CH5) and chitin pentamer (CHIT5) decreased net photosynthetic rate (P N) of soybean and maize, however, on subsequent days there was an increase in P N in some treatments. CH5 caused an increase in maize P N on day 3 at 10–5 and 10–7 M; the increases were 18 and 10 % over the control plants. This increase was correlated with increases in stomatal conductance (g s) and transpiration rate (E), while the intercellular CO2 concentration (C i) was not different from the control plants. P N of soybean plants did not differ from the control plants except for treatment CH5 (10–7 M) which caused an 8 % increase on day 2, along with increased g s, E, and C i. On days 5 and 6 the CHIT5 treatment caused a 6–8 % increase in P N of maize, which was accompanied by increases in g s, E, and C i. However, there was no such increase for soybean plants treated with CHIT5. In general, foliar application of high molecular mass chitin (CHH) resulted in decreased P N, particularly for 0.010 % treated plants, both in maize and soybean. Foliar applications of chitosan and chitin oligomers did not affect (p > 0.05) maize or soybean height, root length, leaf area, shoot or root or total dry mass.  相似文献   

15.
刘燕飞  张羽  赖金美  林威  黄幸然  方熊  易志刚 《生态学报》2020,40(16):5729-5738
羰基硫(COS)和CO2化学结构相似,且植物对COS和CO2具有共吸收特性,因此可利用COS作为示踪物来估算生态系统总初级生产力,而不同植物吸收COS和CO2对环境因子变化的响应差异较大。以南亚热带典型树种马尾松(Pinus massoniana)和杉木(Cunninghamia lanceolata)为研究对象,设置2个氮水平及3个土壤水分梯度处理。采取顶空套袋法采集气体样品,用预浓缩—气质联用仪分析样品COS浓度,同时测量植物光合参数。结果表明:马尾松和杉木吸收COS,吸收速率均值分别为39.58—127.27 pmol m-2 s-1和0.81—66.92 pmol m-2 s-1。整体而言,施氮可促进植物吸收COS,但除施氮对马尾松COS通量有显著影响外(P<0.05),施氮、土壤水分和两者交互作用对马尾松和杉木的COS和CO2通量及其比值均无显著性影响。施氮情况下,高土壤水分处理促进马尾松COS吸...  相似文献   

16.
A family 18 chitinase gene chiA from the thermophile Rhodothermus marinus was cloned and expressed in Escherichia coli. The gene consisted of an open reading frame of 1,131 nucleotides encoding a protein of 377 amino acids with a calculated molecular weight of 42,341 Da. The deduced ChiA was a non-modular enzyme with one unique glycoside hydrolase family 18 catalytic domain. The catalytic domain exhibited 43% amino acid identity with Bacillus circulans chitinase C. Due to poor expression of ChiA, a signal peptide-lacking mutant, chiAsp, was designed and used subsequently. The optimal temperature and pH for chitinase activity of both ChiA and ChiAsp were 70°C and 4.5–5, respectively. The enzyme maintained 100% activity after 16 h incubation at 70°C, with half-lives of 3 h at 90°C and 45 min at 95°C. Results of activity measurements with chromogenic substrates, thin-layer chromatography, and viscosity measurements demonstrated that the chitinase is an endoacting enzyme releasing chitobiose as a major end product, although it acted as an exochitobiohydrolase with chitin oligomers shorter than five residues. The enzyme was fully inhibited by 5 mM HgCl2, but excess ethylenediamine tetraacetic acid relieved completely the inhibition. The enzyme hydrolyzed 73% deacetylated chitosan, offering an attractive alternative for enzymatic production of chitooligosaccharides at high temperature and low pH. Our results show that the R. marinus chitinase is the most thermostable family 18 chitinase isolated from Bacteria so far.  相似文献   

17.
A thermostable chitosanase, purified 156-fold to homogeneity in an overall yield of 12.4%, has a molecular weight of about 29,000±2,000, and is composed of monomer. The enzyme degraded soluble chitosan, colloidal chitosan, and glycol chitosan, but did not degrade chitin or other β-linked polymers. The enzyme activity was increased about 2.5-fold by the addition of 10 mM Co2+ and 1.4-fold by Mn2+. However, Cu2+ ion strongly inhibited the enzyme. Optimum temperature and pH were 60°C and 6.5, respectively. The enzyme was stable after heat treatment at 80°C for 30 min or 70°C for 60 min and fairly stable in protein denaturants as well. Chitosan was hydrolyzed to (GlcN)4 as a major product, by incubation with the purified enzyme. The effects of ammonium sulfate and organic solvents on the action pattern of the thermostable chitosanase were investigated. The amounts of (GlcN)3-(GlcN)6 were increased about 30% (w/w) in DAC 99 soluble chitosan containing 10% ammonium sulfate, and (GlcN)1 was not produced. The monophasic reaction system consisted of DAC 72 soluble chitosan in 10% EtOH also showed no formation of (GlcN)1, however, the yield of (GlcN)3 ~ (GlcN)6 was lower than DAC 99 soluble chitosan-10% ammonium sulfate. The optimal concentration of ammonium sulfate to be added was 20%. At this concentration, the amount of hexamer was increased by over 12% compared to the water-salt free system.  相似文献   

18.
Recently, considerable attention has been focused on chitosan oligosaccharides (COSs) due to their various biological activities. COSs can be prepared by enzymatic degradation of chitosan, which is the deacetylation product of chitin, one of the most abundant biopolymers in nature. In the current study, we recombinantly expressed a chitosanase and used it for COS preparation. A bacillus-derived GH8 family chitosanase with a 6×His tag fused at its N-terminal was expressed in the Escherichia coli strain BL21(DE3) as a soluble and active form. Its expression level could be as high as 500 mg/L. Enzymatic activity could reach approximately 140,000 U/L under our assay conditions. The recombinant chitosanase could be purified essentially to homogeneity by immobilized metal-ion affinity chromatography. The enzyme could efficiently convert chitosan into monomer-free COS: 1 g of enzyme could hydrolyze about 100 kg of chitosan. Our present work has provided a cheap chitosanase for large-scale COS production in industry.  相似文献   

19.
Summary Chitosan:Phormidium aggregates (chitosan: algae=1:2, dry weight basis) were used as a biological tertiary treatment to remove the nitrogen (NH 4 + , NO 2 - , NO 3 - ) and phosphorus (PO 4 3- ) from a secondary effluent. In a batch system, 71 and 92% of P–PO 4 3- were removed after 6 and 24 h, respectively. The orthophosphate removal rate was identical for all three concentrations of algae-chitosan tested (3.3, 4.6, 5.9 g d. wt.·l-1), and was 90 g±2 g P–PO 4 3- ·l-1·h-1, for a 90% removal. Under control conditions (chitosan flakes only added to the effluent) 73 and 78% of PO 4 3- were removed after 6 and 24 h respectively. A 95% removal of inorganic nitrogen (NH 4 + , NO 2 - , NO 3 - ) was attained after 4–6 h withPhormidium immobilized on chitosan flakes, as compared to 30% with chitosan flakes alone (5 g d. wt.·l-1). The system gave a similar performance when operated semi-continuously over 5 days at a daily retention time of 1.0. In the presence of chitosan-immobilized algae, medium P–PO 4 3- levels were reduced by 87.3%±6.4% after 24 h (61.1 g±7.0 g P·l-1·h-1). The reduction of inorganic nitrogen in the medium was 98% after 24 h (370 g±50 g N·l-1·h-1). In the presence of chitosan alone, some 60% orthophosphate removal was recorded, whereas no reduction of nitrogen was observed. Disappearance of orthophosphate was attributed to its co-precipitation with calcium released from the chitosan by abrasion. The presence of the algae protected the chitosan from abrasion andPhormidium directly assimilated the orthophosphate and inorganic nitrogen, thus reducing their levels in the effluent.  相似文献   

20.
The effect of the administration of chitosan (CS) and chitooligosaccharides (COS) on rat fecal microbiota was analyzed in this study. The profile of total bacterial population was monitored during 3 weeks of CS or COS application using denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene amplicons. Quantitative PCR was used for monitoring possible changes in the levels of total bacteria and the levels of individual bacterial groups: Bifidobacteria, Clostridium leptum, Enterobacteriaceae, Lactobacillus–Streptococcus–Enterobacter, and Bacteroides–Prevotella. The DGGE profiles revealed a high complexity and individuality of each tested subject, and variations in the composition of band pattern were observed. CS or COS per os administration changed the profile and structure of the microbial ecosystem of the gastrointestinal tract of healthy rats. COS have, in most cases, an opposite effect compared with CS; only the Bacteroides–Prevotella bacterial group and Enterobacteriaceae were influenced in the same way. The Bifidobacteria group was not influenced by the administration CS and COS.  相似文献   

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