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从64只感染根管中的58只根管分离到144株无芽胞厌氧菌,其中类杆菌54株,厌氧性链球菌23株,韦荣氏球菌17株,真杆菌11株,梭杆菌10株,放线菌8株,双岐杆菌2株,消化链球菌和消化球菌19株。40只根管为厌氧菌和兼性厌氧菌或需氧菌混合感染,18只根管和6只根管分别为单独厌氧菌和兼性厌氧菌感染。33只根尖周炎根管分别采集牙髓和根尖渗出物样本进行培养,实验结果表明牙髓样本中革兰氏阳性厌氧杆菌检出率较高,根尖渗出物中以产黑素类杆菌属的细菌检出率较高。根尖周炎和牙槽脓肿患者的感染根管中产黑素类杆菌属的细菌检出率明显高于蜂窝组织炎患者。 相似文献
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分离并鉴定了329例成人牙周炎龈下优势厌氧菌群,并对不同病程中的菌群变迁、厌氧菌的药物敏感性进行了分析.成人牙周炎龈下标本中厌氧菌阳性检出率为97.9%,其中以牙龈紫质单胞菌检出率最高(38.5%),具核梭杆菌次之(18.9%).随着牙周病变程度的加重,牙龈紫质单胞菌、具核梭杆菌、产黑色素普氏菌、星群厌氧链球菌、厌氧消化链球菌的检出率增高(P<0.05),小韦荣球菌的检出率下降(P<0.01),表明前5种厌氧菌在AP发病过程中有重要作用,小韦荣球菌与之无关.替硝唑、甲硝唑和克林霉素对438株革兰氏阴性厌氧菌的MIC90分别为1~8,2~8和4~16 mg/L,对278株革兰氏阳性厌氧菌的MIC90分别为16~32,16~64和4~16 mg/L,表明替硝唑和甲硝唑体外抗革兰氏阴性厌氧菌效果优于克林霉素,抗革兰氏阳性厌氧菌作用不如克林霉素. 相似文献
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用一次性厌氧菌培养平板,对10属17种67株厌氧菌和30份临床标本进行培养,同时用厌氧手套箱及厌氧罐作对照培养,其培养效果与厌氧手套箱一致,优于厌氧罐,且用一次性厌氧菌培养平板进行培养具有操作简便,宜于推广应用等特点。 相似文献
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儿童乳牙根管感染的细菌学分析 总被引:2,自引:1,他引:1
对18例3~8岁儿童乳牙的根管感染以无菌技术进行定量取样,按种于12种选择性培养基和2种非选择性培养基上,进行需氧、微需氧和厌氧培养,并对细菌菌落计数。对牙髓拟杆菌和牙龈拟杆菌作半定量免疫荧光染色计数;并对其中9例病牙进行了菌相分析。检出的所有细菌中,厌氧菌占绝对优势;其中检出率较高的菌为:产黑色素拟杆菌属,厌氧革兰氏阳性球菌,微需氧革兰氏阳性球菌等.本试验证明,儿童乳牙根管感染是以厌氧菌为主的混合感染,其中以产黑色素拟杆菌属等最常见. 相似文献
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Experiments were carried out to compare the retting of moist flax preserved with sulphur dioxide with that of green dried flax, using whole straw samples. When retted in water at either a constant 20°C or 28°C dried flax was fully retted after 15 and 10 days respectively whereas the sulphur dioxide treated flax (20 g sulphur dioxide kg“1 flax DM) had undergone almost no retting after 20 days at 20dC or 10 days at 28°C. Pre-soaking the treated flax for 24 h in water and changing the acidified water, raised the pH of the retting liquor to a more normal value but did not significantly increase the rate of retting. Addition of the pectinase enzyme preparation ‘Flaxzyme’ to retting liquor at the rate of either 1.5 g kg-1 or 3.0 g kg-1 water, and at a constant temperature of 20°C, substantially increased the rate of retting of both sulphur dioxide treated and dried flax. Optimum degree of retting was achieved at 24 h with the treated flax and at 97 h with the dried flax. Pre-rinsing of the sulphur dioxide treated straw only served to reduce the rate of retting. It was concluded that natural water retting of sulphur dioxide treated flax is retarded by the presence of acidic residues of sulphur dioxide, while enzyme retting is enhanced by these. In further smaller scale experiments using bundles of cut flax straw Flaxzyme was added at concentrations ranging from 0–8.0 ml litre 1 to containers containing flax in water at ratios from 1:10 to 1: 600 flax:water and the producion of galacturonic acid was used as an indicator of retting progress. Retting took place more rapidly at higher flax to water ratios for a given enzyme concentration. This effect was attributed to the lower pH of higher flax to water ratios which created pH conditions closer to the pH optimum for the retting enzymes. When enzyme retting was compared at a range of buffered pH's the optimum was pH 4.0. At a buffered pH of 4.0 and a temperature of 19°C, retting of sulphur dioxide treated moist flax (flax to water ratio of 1:10) was achieved with Flaxzyme concentrations as low as 0.5 ml litre”‘,much lower than the previously reported minimum of 3.0 ml litre’. 相似文献
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Identification and Retting Efficiencies of Fungi Isolated from Dew-Retted Flax in the United States and Europe 总被引:5,自引:0,他引:5
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G. Henriksson D. E. Akin R. T. Hanlin C. Rodriguez D. D. Archibald L. L. Rigsby K. L. Eriksson 《Applied microbiology》1997,63(10):3950-3956
Seven strains of filamentous fungi and one yeast were isolated from flax that was dew retted in the United States. These filamentous fungi were subcultured to purity and identified, and six appear not to have been reported earlier as isolates from dew-retted flax. Five of the purified U.S. strains, two fungi isolated from flax that was dew retted in Europe, and a laboratory culture of Aspergillus sojae were tested for their ability to ret flax stems. The monocultures were evaluated for the degree of retting, fiber strength, dry weight loss, and tactile response (i.e., feel of softness) as reflected in the retted fiber. Structural modifications of representative samples of the retted flax were assessed by scanning electron microscopy. All of the filamentous fungi were able to carry out some retting, whereas the isolated yeast could not. All organisms produced pectinases when they were cultivated in shake flasks on ball-milled flax as the sole carbon source. Some fungi also produced cellulases, mannanases, and xylanases. Rhizomucor pusillus and Fusarium lateritium were noteworthy as retting organisms by their high level of pectinase activity, ability to attack noncellulosic cell types without attacking cellulose, capacity to penetrate the cuticular surface of the stem, and efficient fiber release from the core. The results indicated that these organisms deserve further study as potential organisms for retting of bast fibers in industrial applications. 相似文献
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G. W. Wieringa 《Antonie van Leeuwenhoek》1963,29(1):84-88
The pectinase produced during the anaerobic retting of flax appeared to have a pH optimum between 5.4 and 5.6. Continuous neutralization during the fermentation, however, induced the production of a pectinase with a pH optimum of 7.1.The majority of the pectin splitting bacteria in the acid and in the neutral retting liquors belonged to the speciesClostridium pectinovorum.Pure culture studies withCl. pectinovorum at fixed pH levels showed that the pectinase produced is adapted to the pH of the environment. No differences in pH dependency could be established between the hemicellulases from the acid and the neutral retting liquor.Although a pH of 6.5 is far from optimal for the hemicellulase, the actual hemicellulolytic activity in the neutral pH retting method is greater than the activity of the normal, acid retting liquor. This fact supports the theory that hemicellulase is responsible for losses in fibre quality and quantity in the neutral pH retting method. 相似文献
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This study demonstrates the power of multiproxy palaeolimnological analyses in investigating environmental changes in the Lake Kooraste Linajärv ecosystem through historical time in response to flax retting. Flax retting history was proven by applying pollen and macrofossil evidence and by using several biotic and geochemical proxies on a sediment core. Continuous findings of flax pollen and macrofossil remains in lake sediments were considered as strong evidence for the occurrence of retting. Analyses of the well-dated sediment core show the consequences of flax retting in the lake. As a result, the once clear soft water oligotrophic endorheic lake with limited sedimentation has turned into a hypertrophic high-sedimentation lake with anoxic bottom water, strong stratification and intense water blooms. Despite the fact that flax retting was forbidden in Estonia around ad 1950s and retting has not occurred over the last six decades, anthropogenic alterations were so pervasive in the past, that they have prevented any lake water improvements until the present-day. 相似文献
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Flax dew-retting is widely adopted in most flax-growing countries, but it does not represent a practical solution where dry weather conditions occur after harvest. A study of the local microbiological aspects was undertaken as a contribution to improve field-retting of flax under southern European climates. Fungi were isolated from soil and dew-retted flax in northern Italy, and 23 representative strains were chosen to test their ability to ret flax stems. Experiments were performed in vitro on flax stem pieces artificially inoculated with single fungal strains. Retting degree was assessed with a mechanical test, to evaluate the ease with which the bast was detached from the wood core, and by the analysis of the residual fibre pectins using uronic acid. Uronic acid dosage provided a better differentiation of the strains than the mechanical test. There was a large variability in retting ability among the species assayed and even among strains of the same species. The best results were obtained with all Aspergillus and Penicillium strains, while Mucor and Rhizopus strains showed a variable retting ability. Fusarium, Trichoderma strains and Epicoccum nigrum had the poorest retting abilities among all the fungal strains assayed. 相似文献
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To determine the optimum conditions for inducing retting of flax, by the application of glyphosate herbicide, it is necessary to have an easily portable tool which will give a rapid, accurate assessment of the stage that retting has reached. Such a tool, which can be used to test individual stems, is described and the estimates of retting obtained compared with those from other methods. 相似文献
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Polygalacturonase is the key component in enzymatic retting of flax 总被引:18,自引:0,他引:18
Seven commercial enzyme mixtures were tested for their ability to perform retting of flax (i.e. to separate flax fibers by partly removal of middle lamella) and were assayed for hydrolysis of xylan, cellulose and four kinds of pectin. The only activity that showed correlation to the ability to perform retting was the degradation of low esterfied pectin. A purified Aspergillus niger polygalacturonase was also shown to be able to perform retting. From this data it is hypothesized that degradation of the smooth regions (i.e. non-methylated polygalacturonase) in the middle lamella pectin is the most important step in enzymatic retting. 相似文献
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The fungi present on glyphosate-treated flax plants were isolated. Cladosporium herbarum, Epicoccum nigrum, Botrytis cinerea and yeasts occurred most frequently immediately after glyphosate treatment but as retting progressed the frequency of occurrence of Fusarium culmorum, Alternaria alternata and a Phoma sp. increased. Many of the fungi isolated from retting flax were also present as epiphytes on healthy flax stems. Glyphosate was shown to be fungitoxic in vitro but it had only a very slight effect on fungi colonising the flax. The application of sucrose and urea to flax 1 wk after glyphosate treatment resulted in more rapid fungal colonisation of the stems, but did not significantly enhance retting. When grown on sterilised flax stem sections, fungi known to be saprophytic on flax produced polysaccharide-degrading enzymes. All seven fungi tested produced polygalacturonase, pectin-lyase and xylanase. The greatest cellulase activity was present in stem tissues inoculated with F. culmorum and the Phoma sp. while no cellulase was detected in tissue inoculated with B. cinerea, a Mucor sp. or a Penicillium sp. Extracts from flax inoculated with the cellulolytic fungi caused the solubilisation of native cellulose. Pectinases, xylanase and cellulase were also detected in naturally-colonised senescing and dead flax stems. Stems which had been treated with a sucrose solution tended to contain the greatest enzyme activity. 相似文献