壳聚糖的抗菌活性研究

以大肠杆菌和金黄色葡萄球菌为实验菌,研究壳聚糖的抗菌活性.结果表明:分子量大的壳聚糖对大肠杆菌和金黄色葡萄球菌都有较强的抑菌作用.梯度稀释结果显示,两种壳聚糖的MIC均为:0.05%抑制大肠杆菌,0.025%抑制金黄色葡萄球菌.研究壳聚搪的抑菌机理时发现,当壳聚糖形成纳米粒子时其抑菌能力丧失,推测抑菌作用可能与壳聚糖上氨基的质子,化有密切关系.壳聚糖抑菌可能是因为壳聚糖上的氨基(NH2 )与细菌细胞壁中带负电荷的磷壁酸或脂多糖结合,并螯合Mg2 、Ca2 等阳离子,从而改变细胞壁的通透性,起到押菌作用.     

Antibacterial activity of chitosan against Aeromonas hydrophila

The effect of chitosan on growth and production of haemolysin by Aeromonas hydrophila was investigated as well as the effects of temperature, pH, salts and irradiation on the antibacterial activity of chitosan. It was found that chitosan affected growth and haemolysin production of A. hydrophila in varying degrees compared to the control. Growth and haemolysin production were clearly suppressed at 0.04% of chitosan. Suppression was more effective at pH 6.0 than at pH 7.0. The bactericidal effects of chitosan increased with increasing temperature and decreasing pH. Divalent cations at concentrations of 10 and 25 mM reduced the antibacterial activity of chitosan, in the order of Ba2+ > Ca2+ > Mg2+. Sodium ions at concentrations of 10 and 25 mM also reduced chitosan's activity. Irradiation of chitosan at 150 kGy under dry condition was effective in slightly increasing its activity.     

Antibacterial activity of N-alkylated disaccharide chitosan derivatives

Antibacterial activity of the water-soluble N-alkylated disaccharide chitosan derivatives against Escherichia coli and Staphylococcus aureus was investigated. It was found that the antibacterial activity of chitosan derivatives was affected by the degree of substitution (DS) with disaccharide and the kind of disaccharide present in the molecule. Regardless the kind of disaccharide linked to the chitosan molecule, a DS of 30-40%, in general, exhibited the most pronounced antibacterial activity against both test organisms. E. coli and S. aureus were most susceptible to cellobiose chitosan derivative DS 30-40% and maltose chitosan derivative DS 30-40%, respectively, among the various chitosan derivatives examined. Although the disaccharide chitosan derivatives showed less antibacterial activity than the native chitosan at pH 6.0, the derivatives exhibited a higher activity than native chitosan at pH 7.0. Antibacterial activity of the chitosan derivatives (DS 30-40%) against E. coli increased as the pH increased from 5.0 and reached a maximum around the pH of 7.0-7.5. The effect of pH on the antibacterial activity of chitosan derivatives against S. aureus was not as pronounced as that observed with E. coli. Population reduction of E. coli or S. aureus in nutrient broth increased markedly upon increasing the concentration of chitosan derivatives from 0 to 500 ppm. No marked increase in population reduction was noted with further increase in the concentration of chitosan derivatives even up to 2000 ppm.     

Antibacterial activity of shrimp chitosan against Escherichia coli

The effects of cell age, reaction temperature, pH value, and salts on the inhibitory activity of shrimp chitosan (98% deacetylated) against Escherichia coli were investigated. The age of a bacterial culture affected its susceptibility to chitosan, with cells in the late exponential phase being most sensitive to chitosan. Higher temperature (25 and 37 degrees C) and acidic pH increased the bactericidal effects of chitosan. Sodium ions (100 mM Na+) might complex with chitosan and accordingly reduce chitosan's activity against E. coli. Divalent cations at concentrations of 10 and 25 mM reduced the antibacterial activity of chitosan, in the order of Ba2+ > Ca2+ > Mg2+. Chitosan also caused leakage of glucose and lactate dehydrogenase from E. coli cells. These data support the hypothesis that the mechanism of chitosan antibacterial action involves a cross-linkage between the polycations of chitosan and the anions on the bacterial surface that changes the membrane permeability.     

溶菌酶与壳聚糖复配液抑菌作用的研究

本实验以溶菌酶和壳聚糖联合使用以增强对三种模型菌(大肠杆菌(E.coli)、金黄色葡萄球菌(St.aureus)及白色念珠菌(C.albicans))的抑菌效果。首先采用抑菌圈法考察不同浓度醋酸溶液对不同浓度壳聚糖溶液抑菌效果的影响,其次通过对倍稀释法测定壳聚糖溶液和溶菌酶溶液的最小抑菌浓度(MIC),并采用定量法确定复配液的配比,最后通过酶标法监测加入复配抑菌剂后三种模型菌的生长曲线。结果表明,1%的醋酸溶液与壳聚糖的协同抑菌效果最好;壳聚糖溶液对三种模型菌的最小抑菌浓度均为0.1562mg/m L,溶菌酶溶液对大肠杆菌、金黄色葡萄球菌和白色念珠菌的最小抑菌浓度分别为0.625mg/mL、1.25mg/mL和1.25mg/mL,而复合液对三种模型菌的抑制作用优于单独使用溶菌酶或壳聚糖;复配液对大肠杆菌和金黄色葡萄球菌的抑制作用主要表现在对数生长期,而加入材料后白色念珠菌由延迟期直接进入稳定期内。     

壳聚糖和黄芩甙对毛织物的抗菌整理

以壳聚糖和中草药黄芩甙提取物为整理剂对纯毛织物进行抗菌整理,采用浸轧法,利用单因素的分析方法,对不同质量浓度抗菌剂、不同焙烘温度、不同焙烘时间进行实验,并对整理后织物的抑菌性能进行测试分析,结果表明:整理后的织物对大肠杆菌、金黄色葡萄球菌、枯草杆菌抗菌效果较好,抗菌率在92%以上,水洗20次后金黄色葡萄球菌抗菌率仍在80%以上,并基本保留织物原有风格及服用性能.抗菌整理对白度和透气性影响不大.实验确定了最佳抗菌剂质量浓度为20～25 g/L,最佳焙烘温度为110℃.     

Antibacterial activity of chitosans and chitosan oligomers with different molecular weights

Antibacterial activities of six chitosans and six chitosan oligomers with different molecular weights (Mws) were examined against four gram-negative (Escherichia coli, Pseudomonas fluorescens, Salmonella typhimurium, and Vibrio parahaemolyticus) and seven gram-positive bacteria (Listeria monocytogenes, Bacillus megaterium, B. cereus, Staphylococcus aureus, Lactobacillus plantarum, L. brevis, and L. bulgaricus). Chitosans showed higher antibacterial activities than chitosan oligomers and markedly inhibited growth of most bacteria tested although inhibitory effects differed with Mws of chitosan and the particular bacterium. Chitosan generally showed stronger bactericidal effects with gram-positive bacteria than gram-negative bacteria in the presence of 0.1% chitosan. The minimum inhibitory concentration (MIC) of chitosans ranged from 0.05% to >0.1% depending on the bacteria and Mws of chitosan. As a chitosan solvent, 1% acetic acid was effective in inhibiting the growth of most of the bacteria tested except for lactic acid bacteria that were more effectively suppressed with 1% lactic or formic acids. Antibacterial activity of chitosan was inversely affected by pH (pH 4.5-5.9 range tested), with higher activity at lower pH value.     

壳聚糖食品保鲜膜抗菌性及其应用的研究进展

壳聚糖由于其良好的功能特性,近年来作为天然保鲜包装材料在各类食品的包装中已有大量的应用。该文章在对壳聚糖食品薄膜材料的抗菌机理总结的基础上,对近年来壳聚糖薄膜在食品的研究及应用现状进行了综述,并对壳聚糖食品薄膜的未来发展趋势进行了展望。     

TG酶催化丝胶和壳聚糖对羊毛织物的抗菌整理

为了提高羊毛织物的抗菌性能,以处理后羊毛织物的增重率为考核指标,采用谷氨酰胺转胺酶(TG酶)催化丝胶、壳聚糖和羊毛的接枝反应,对羊毛织物进行整理。利用X-射线光电子能谱、扫描电子显微镜(SEM)和热重分析对比织物整理前后的变化,结果表明丝胶和壳聚糖与羊毛发生接枝反应。整理后羊毛织物对金黄色葡萄球菌和大肠杆菌的抑菌率都大于99%,断裂强力提高,白度有所下降。经20次水洗后,对金黄色葡萄球菌和大肠杆菌抑菌率分别为86.8%和83.9%,说明具有很好的抗菌性能。     

氧化石墨烯-壳聚糖改性丙纶非织造布抗菌性能研究

为提高丙纶非织造布的抗菌性能,拓展丙纶非织造布的应用范围,将氧化石墨烯、壳聚糖应用于丙纶非织造布.利用静电吸附作用,通过层层自组装将壳聚糖分子与氧化石墨烯分子整理到丙纶非织造布的表面,然后对改性丙纶非织造布进行红外光谱、染色深度、抗菌性能及拉伸性能测试.结果 表明:壳聚糖与氧化石墨烯能在丙纶非织造布表面进行有效的自组装整理;抗菌测试数据表明,经过8次自组装改性整理的丙纶非织造布具有优异的抗菌性能,且抗菌水洗稳定性良好;自组装改性整理后的丙纶非织造布的断裂强力也略有提升.     

恒定磁场强化羟丙基壳聚糖的抑菌与吸附性能

研究恒定磁场对羟丙基壳聚糖的抑菌与吸附性能的强化作用,以提高其应用效果。从对金黄色葡萄球菌的抑菌圈、抑菌曲线和最低抑菌浓度三个方面分析其抑菌性能;从对铜和铬两种金属离子的吸附动力学分析其吸附性能。结果表明:经恒定磁场作用后,羟丙基壳聚糖的抑菌性能和吸附性能都得到改善,当羟丙基壳聚糖在浓度为50mg/mL时,抑菌圈的直径增加约3·2mm;发挥抑菌作用的时间也相对提前了;最低抑菌浓度为1·5625mg/mL,降低了一半;对Cu(II)的吸附率和吸附量分别增加约6·11%和0·1833mg/g;对Cr(VI)的吸附率和吸附量分别增加约6·35%和0·09523mg/g。     

壳聚糖及其衍生物的抗菌机理及在纺织品抗菌整理中的应用

介绍了壳聚糖的性质,壳聚糖的抗菌机理,详述了影响壳聚糖抑菌性能的因素、壳聚糖及其衍生物作为抗菌剂在纺织品抗菌整理中的应用以及抗菌织物的耐洗性.     

Antibacterial activity of chitin,chitosan and its oligomers prepared from shrimp shell waste

The antimicrobial activities of chito-oligosaccharides against four Gram-positive and seven Gram-negative bacteria were compared to chitosan and chitin with an emphasis on the effects of biopolymer molecular weight (Mv) and degree of deacetylation (DD). Chitin was isolated from shrimp (Parapenaeus longirostris) shell waste by sequential chemical treatments. Chitosan and its oligomers N-acetyl chito-oligosaccharides and chito-oligosaccharides were prepared by deacetylation and chemical hydrolysis, respectively. Chitin exhibited a bacteriostatic effect on Gram-negative bacteria, Escherichia coli ATCC 25922, Vibrio cholerae, Shigella dysenteriae, and Bacteroides fragilis. Chitosan exhibited a bacteriostatic effect on all bacteria tested, except Salmonella typhimurium. The oligomers exhibited a bactericidal effect on all bacteria tested.     

Antibacterial action of vegetable extracts on the growth of pathogenic bacteria

Under controlled conditions, extracts of garlic, onion, turnip, green peppers and radishes were used to inhibit Escherichia coli, Salmonella typhosa, Shigella dysentriae and Staphylococcus aureus, which are all pathogenic bacteria. It was found that 1–4% by vol. of garlic extract completely inhibited the growth of all the bacteria used. 4% by vol. of onion extract completely inhibited the growth of both Shigella dysentriae and Staphylococcus aureus at 10^–6 dilution. Salmonella typhosa and E. coli were not completely inhibited; the inhibition was 48·3% for E. coli and 95·3% for Salmonella typhosa. At 10^–4 bacterial dilution, onion extract decreased the colony number substantially in all four bacteria. 4% extracts from turnip, green peppers and radishes did not show a definite antibacterial action against any bacterium at the given dilutions. On the contrary some growth stimulating activity of these extracts on some bacteria was observed.     

Antibacterial effects of chitosan solution against Legionella pneumophila, Escherichia coli, and Staphylococcus aureus

Chitosan has been shown to have antibacterial activities on the growth of a wide variety of bacteria. Chitosan solution has been sold commercially for use as an antibacterial agent. Chitosan solution contains not only chitosan but also organic acids as solvents and desalted Japan Sea Proper Water (dJSPW). We aimed to clarify whether chitosan solution has antibacterial activity against bacteria invading bath water, and then to explore the causative factor among these ingredients. The antibacterial activity of full-strength chitosan solution and of 10(2)- and 10(4)-fold chitosan solution diluted with purified water was studied against Legionella pneumophila serogroups 1 (L. pneumophila SG1) and 6 (L. pneumophila SG6), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) for 7 days at 37 degrees C. To clarify the causative factor in the antibacterial activity against E. coli, the antibacterial activities of the full-strength and diluted chitosan solutions for 24 h were examined. L. pneumophila SG1 and SG6, and E. coli could not survive in the chitosan solution or in the 10(2)-fold dilute solution for over a day at 37 degrees C. The cells of S. aureus were found to have decreased more than 2.46 log cfu/ml after 1 day of incubation, not only in the chitosan solutions, but also in phosphate buffer solution as a control. No inhibitory effect of dJSPW on the growth of the bacteria was observed. The antibacterial activity of the chitosan solution was lower compared with those of the organic acids solutions, and it increased with decreasing pH value. We observed the antibacterial activity of chitosan solution against L. pneumophila SG1 and SG6, and E. coli, suggesting it may be due to the decreased pH value derived from organic acids rather than from chitosan itself or dJSPW.     

丁香油、百里酚复合壳聚糖处理对桃采后褐腐病菌的抑制作用

为了进一步提高壳聚糖用于涂膜时的综合抗菌能力,采用滤纸片法及菌丝扩展法测定并对比了丁香油和百里酚对桃采后致病褐腐菌的抗菌能力及用微孔板法测定了它们的最小抑菌浓度,并将丁香油、百里酚复合壳聚糖对桃果进行涂膜,测量果体经过涂膜和接菌后的病斑扩展。结果表明丁香油和百里酚都具有较好的抗褐腐菌能力,百里酚强于丁香油,复合壳聚糖涂膜时二者都可以提高壳聚糖总体抗菌能力且复合百里酚效果较好。二者具有作为壳聚糖涂膜保鲜添加剂的应用潜力。     

Antibacterial mode of action of seed essential oil of Eleutherococcus senticosus against foodborne pathogens

This study investigated the antibacterial mechanism of action of the seed essential oil of Eleutherococcus senticosus (ESEO) against foodborne pathogenic bacteria. Preliminarily, the ESEO (1000 μg disc^?1) showed potential antibacterial effect as diameter of inhibition zones (12.0 ± 0.2–37.0 ± 2.0 mm) against the tested foodborne pathogens. The MIC and MBC values of ESEO against the tested bacteria were found in the range of 125–500 and 500–1000 μg mL^?1, respectively. At MIC concentration, the ESEO had potential inhibitory effect on the cell viability of the tested pathogens. In addition, SEM analysis showed the inhibitory effect of ESEO as confirmed by considerable morphological alterations on the cell wall of B. cereus ATCC 13061 and E. coli O157:H7 ATCC 43889. Moreover, the ESEO revealed its mode of action against foodborne pathogens on membrane integrity as confirmed by release of extracellular ATP, 260‐nm absorbing materials and leakage of potassium ions. These findings confirm that the ESEO can be used as a potential antibacterial agent in food industry to inhibit the growth of various foodborne pathogens.     

Antibacterial activity of a chitooligosaccharide mixture prepared by cellulase digestion of shrimp chitosan and its application to milk preservation

The antibacterial activity of a chitooligosaccharide mixture prepared by digestion of shrimp chitosan with cellulase at 50 degrees C for 14 h was evaluated. Sugars with 1 to 8 degrees of polymer (DP) were found in this chitooligosaccharide mixture, and the weight percentage of sugars with DP > or = 6 was 44.3%. Minimal lethal concentrations of this mixture against Aeromonas hydrophila, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, Shigella dysenteriae, Staphylococcus aureus, Vibrio cholerae, and Vibrio parahaemolyticus in nutrient broth were 5 to 29 ppm, which were much lower than those of the chitosan reactant (50 to 1,000 ppm). The antibacterial activity of this mixture in the sterilized milk against E. coli O157, L. monocytogenes, Salmonella Typhimurium, and S. aureus was much stronger at 4 degrees C than at 37 degrees C. When raw milk was supplemented with either 0.24% or 0.48% (wt/vol) of this oligosaccharide mixture and stored at 4 degrees C for 12 days, its mesophilic and psychrotrophic counts were reduced by at least 3 log cycles, and there was very little change in pH. In addition, this mixture retarded the growth of Salmonella species and caused quicker reduction of Staphylococcus species in raw milk. Accordingly, the shelf life of raw milk at 4 degrees C was extended by at least 4 days.     

Antimicrobial properties of chitosan and mode of action: a state of the art review

Owing to its high biodegradability, and nontoxicity and antimicrobial properties, chitosan is widely-used as an antimicrobial agent either alone or blended with other natural polymers. To broaden chitosan's antimicrobial applicability, comprehensive knowledge of its activity is necessary. The paper reviews the current trend of investigation on antimicrobial activities of chitosan and its mode of action. Chitosan-mediated inhibition is affected by several factors can be classified into four types as intrinsic, environmental, microorganism and physical state, according to their respective roles. In this review, different physical states are comparatively discussed. Mode of antimicrobial action is discussed in parts of the active compound (chitosan) and the target (microorganisms) collectively and independently in same complex. Finally, the general antimicrobial applications of chitosan and perspectives about future studies in this field are considered.     

Antimicrobial action of hydrolyzed chitosan against spoilage yeasts and lactic acid bacteria of fermented vegetables

The antimicrobial properties of various chitosan-lactate polymers (ranging from 0.5 to 1.2 MDa in molecular weight) against two yeasts isolated from fermented vegetables and against three lactic acid bacteria from a mixed starter for sauerkraut on methylene blue agar (MBA) and in vegetable juice medium (VJM) were investigated. Chitosan-lactate reduced the growth of all microorganisms in solid (MBA) as well as in liquid (VJM) medium. In MBA, a concentration of 5 g/liter was needed to inhibit the growth of Saccharomyces bayanus, while 1 g/liter was sufficient to inhibit the growth of Saccharomyces unisporus. Lactic acid bacteria were also inhibited in this range of concentrations. The low-molecular-weight chitosan-lactate DP3 (0.5 kDa) was most efficient in solid medium (MBA), and inhibitory activities decreased with increasing hydrolysate lengths. In liquid medium (VJM), 0.5 g of chitosan-lactate per liter reduced the growth rates for both yeasts, but 10 g/liter was insufficient to prevent yeast growth. Intermediate-molecular-weight chitosan-lactate (5 kDa) was more efficient than chitosan of low molecular weight. Native chitosan (1.2 MDa) showed no inhibition in either medium. Microscopic examination of S. unisporus Y-42 after treatment with chitosan-lactate DP25 showed agglutination of a refractive substance on the entire cell wall, suggesting an interaction between chitosan and the cell wall. When chitosanase was added to the culture media containing chitosan-lactate, refractive substances could not be observed.