产H_2O_2的乳酸杆菌分离培养基的改良

对MRS培养基的使用方法进行了改良。将MRS(含0.25 mg/ml TMB)融化后倾倒入平皿,待其凝固后,在琼脂表明加入200μl(0.01 mg/ml)HRP,涂匀后进行乳酸杆菌划线分离。37℃、厌氧培养48~72 h。结果表明,产生H2O2的乳酸杆菌呈蓝色菌落,和原来的培养方法相比,改良的方法简便经济、HPR的使用量为原来的1%,分离产H2O2的乳酸杆菌的效果良好。     

Effect of Storage of Mueller-Hinton Agar Plates on Zone Sizes for Antimicrobial Testing

The length of time Mueller-Hinton agar plates can be stored at 4 C without affecting the size of zones of inhibition in susceptibility testing by the Bauer-Kirby method was studied. It was found that these plates can be stored for 3 weeks at 4 C without an appreciable affect on zone sizes. Storage of plates in sealed plastic bags did not alter the results significantly. The findings indicate that commercially prepared Mueller-Hinton agar plates, which may be several days old when received at the laboratory, are suitable for use in routine susceptibility tests by the Bauer-Kirby method.     

Extraction of nontype-specific antigens of group A Streptococcus by potassium thiocyanate

A method for extraction of nontype-specific antigens of the group A streptococcus cellular wall from whole microbial cells is described. Potassium thiocyanate was used as an extracting agent. Nontype-specific antigens of the thiocyanate extract purified by ammonium sulfate precipitation were examined by immunodiffusion in agar gel. The thiocyanate extracts were found to contain several nontype-specific protein antigens part of which were absent from the HCl-extracts. No group A streptococcal polysaccharide was found in the thiocyanate extracts.     

Biotin-labeled plasmid DNA probes for detection of epithelium-associated strains of lactobacilli

Biotin-labeled DNA probes prepared from whole plasmids (5.5 and 4.8 kilobases) of two lactobacillus strains (Lactobacillus delbrueckii 21 and Lactobacillus reuteri 100-23) were used to detect the homologous bacteria in microtome-cryostat-prepared sections of murine forestomach. The forestomach sections were incubated on nylon filter membranes placed on agar plates and, after lysis of the lactobacillus cells and denaturation of their DNA, were used in hybridization experiments with the strain-specific DNA probes. Hybridization of the probes to membranes containing sections from lactobacillus-free mice did not occur. The probes detected the presence of homologous strains of lactobacilli in sections cut from the forestomach of mice harboring one or both of the strains.     

Biotin-labeled plasmid DNA probes for detection of epithelium-associated strains of lactobacilli.

Biotin-labeled DNA probes prepared from whole plasmids (5.5 and 4.8 kilobases) of two lactobacillus strains (Lactobacillus delbrueckii 21 and Lactobacillus reuteri 100-23) were used to detect the homologous bacteria in microtome-cryostat-prepared sections of murine forestomach. The forestomach sections were incubated on nylon filter membranes placed on agar plates and, after lysis of the lactobacillus cells and denaturation of their DNA, were used in hybridization experiments with the strain-specific DNA probes. Hybridization of the probes to membranes containing sections from lactobacillus-free mice did not occur. The probes detected the presence of homologous strains of lactobacilli in sections cut from the forestomach of mice harboring one or both of the strains.     

Use of Fast Green in Agar-Diffusion Microbiological Assays

Microbiological assay plates containing agar stained with fast green and inoculated with test microorganisms could be readily distinguished from unstained seeded agar plates. The boundaries of zones of growth inhibition were more sharply defined in those plates which contained stained agar.     

Heterofermentative metabolism of glucose and ribose and utilisation of citrate by the smooth biotype of Lactobacillus amylovorus NCFB 2745

Lactobacillus amylovorus NCFB 2745 exhibits a rough colony morphology, ferments glucose homofermentatively and cannot utilise ribose. After five transfers in de Man Rogosa and Sharpe media (containing glucose and citrate) Lb. amylovorus 2745 appears smooth on agar plates; smooth cultures reverted to rough by culturing in aerobic conditions. The smooth type shows patterns of fermentation that are typical of a heterofermentative lactobacillus. Thus, the smooth morphotype produces CO₂ and ethanol in addition to lactate and is able to ferment ribose. The switch in metabolism to the smooth form is accompanied by an increase in phosphoketolase and a reduction in aldolase enzyme activities. Citrate also has effects on growth rates and end-metabolites.     

Detection of Lactobacillus acidophilus in Feces of Humans, Pigs, and Chickens

Lactobacilli in fecal material from humans, pigs, and chickens were enumerated on lactobacillus selective agar (LBS). In all samples, higher numbers of lactobacilli were detected when plates were incubated in a system flushed with CO₂ rather than in air. Much higher numbers of bacteria from human feces were detected when the LBS agar plates were incubated anaerobically in a hydrogen-carbon dioxide atmosphere (GasPak) than when incubated in CO₂. The bacteria from human feces isolated on LBS agar incubated anaerobically were predominately bifidobacteria. Cultures from all three sources isolated on LBS agar incubated under CO₂ were lactobacilli, including Lactobacillus acidophilus. Differences were observed in biochemical characteristics of some of the L. acidophilus isolated from all three sources. Guanine plus cytosine base ratios of deoxyribonucleic acid isolated from L. acidophilus cultures from humans were lower, in most cases, than those from pigs and chickens.     

A Modification of the Mycoplasma Serum-Drop Growth Inhibition Test

A modification of the serologic mycoplasma growth inhibition test is described. It is based on application of a drop of antiserum directly onto the centre of an inoculated agar plate provided with a slightly concave agar surface. The special apparatus devised for the preparation of these plates is described. This modified serum-drop method is more sensitive than other growth inhibition tests used today and is equally specific.     

具有抑制单胺氧化酶作用的干酪乳杆菌JH-23的药敏性研究

采取纸片琼脂扩散法对具有抑制单胺氧化酶作用的干酪乳杆菌JH-23进行抗生素的敏感性测定.考察了不同菌液浓度、培养时间和接种方式对药敏性实验的影响,在此基础上建立了其对12类30种抗生素的药敏谱,以进一步全面评估该益生菌的安全性.     

肠易激综合征患者服用酪酸菌制剂前后肠道菌群状况

治疗ＩＢＳ,观察酪酸菌制剂的临床疗效及肠道菌群状况。从门诊随机选择２１例男性,９例女性。检测大便常见菌群和病原菌,采用Ｍｉｌｅｓ－Ｍｉｓｒｏ介绍的滴注法操作。每次培养时均选上述细菌标准菌株一同培养作质控。治疗前总厌氧菌、双歧杆菌和乳酸杆菌下降,而有潜在致病性的梭菌明显下降。无致病菌生长。治疗后腹泻次数明显减少。总有效率为８３４％,双歧杆菌和乳酸杆菌升高明显。结论：ＩＢＳ易致肠菌失调,酪酸菌能抑制肠道内腐败菌、病原菌,并能促进双歧杆菌、乳酸菌等肠道内的有益菌发育。     

Novel and rapid agar plate methods for in vitro assessment of bacterial biocontrol isolates’ antagonism against multiple fungal phytopathogens

Biological control of plant diseases with antagonistic bacteria is a promising alternative to conventional chemical control strategies. In vitro screening for inhibition of mycelial growth of phytopathogenic fungi by bacterial isolates is the first step in selecting putative bacterial biocontrol agents. Dual culture plate assay is the most common method involved in this first-line selection process. However, it needs independent agar plates to test antagonism by a specific bacterial isolate against each of the fungal phytopathogen. Two modified in vitro antagonism tests are proposed here. Antagonistic activity of a putative biocontrol bacterial strain against four different fungal phytopathogens could be assessed in a single agar plate simultaneously. A comparison of the new methods with conventional dual culture plate assay was also done. The proposed methods are easy to perform and results of antagonism are obtained rapidly. Results of fungal inhibition were qualitatively comparable with that generated through dual culture plate assay. Quantity of resources such as agar medium and plates required for the modified antagonistic assays is several folds less than that required for dual culture plate assay.     

Increase in Sensitivity for the Assay of Neomycin in Milk

A study was conducted to design a more sensitive and flexible technique for the assay of neomycin in milk. Sterile Antibiotic Assay medium (Difco; 15 ml) was poured into glass petri dishes with aluminum tops equipped with absorbent discs. Seed agar (4 ml; containing 1% sodium chloride) inoculated with standardized amounts of the test organism (Staphylococcus epidermidis ATCC 12228) was laid over the hardened base agar, and stainless-steel cylinders were placed equal distances apart in the agar. The plates were refrigerated for 30 min and the cups were removed in an atmosphere of minimal contamination. The resultant holes were sealed with melted agar. After preparation, the holes were used for assay procedures. Samples to be assayed were pipetted into the holes and the plates were refrigerated for 90 min at 4 C. Plates were incubated for 18 to 20 hr at 32 C. The zones of inhibition were recorded and compared with a standard curve. The approximate sensitivity of this method was 0.05 mug/ml.     

双平板对照筛选跟踪分离细菌外排泵抑制剂

建立了细菌外排泵抑制剂的筛选与活性跟踪方法.准备2个平板,一个为普通营养琼脂平板,另一个为舍小蘖碱的普通营养琼脂平板,通过比较两个平板含药纸片周围抑菌圈的直径大小判断筛选结果,方法可靠稳定.筛选发现某霉菌提取物对细菌外排泵有抑制活性,经活性跟踪分离,得到单体化合物,经NMR鉴定为4′,5,7-三羟基异黄酮.方法简便易行,成本低,适宜于对大批样本进行快速筛选并在分离时进行活性跟踪.     

1株植物乳杆菌的抑菌作用及其生物学特性的研究

植物乳杆菌（Lactobacillus plantarum）是乳酸杆菌中的一种,常存在于发酵的蔬菜和果汁中。植物乳杆菌作为人体肠道的益生菌群,具有维持肠道菌群平衡、提高机体免疫力和促进营养物质吸收等多种作用。研究从市售腌渍蔬菜中分离筛选获得一株植物乳杆菌,以9种菌作为指示菌,采用牛津杯琼脂扩散法检测筛选菌株的抑菌谱大小。结果表明,该菌株能较强的抑制大肠杆菌、柠檬色葡萄球菌、藤黄微球菌和枯草芽孢杆菌等指示菌。此外,研究了菌株对温度的稳定性,p H值的耐受性及其酶的敏感性等生物学特性,结果显示该株植物乳杆菌菌株具有良好的热稳定性,酸碱稳定性,并且对3种蛋白酶具有很好的敏感性。这为今后深入研究与开发植物乳杆菌奠定了基础。     

Comparison of Media for Detection of Fungi on Spacecraft

Five media, including Trypticase soy agar (TSA; BBL) pour plates, spread plates of TSA, Mycophil agar with chloromycetin, Mycophil agar with chloromycetin and Actidione, and cornmeal agar with chloromycetin were quantitatively and qualitatively compared for the detection of fungi on spacecraft. Cornmeal agar with chloromycetin yielded the highest number of fungal colonies, although not always significantly higher than Mycophil agar with chloromycetin or TSA spread plates. Cornmeal agar with chloromycetin also gave the best qualitative representation of fungi on the spacecraft, recovering 68% of the genera found from all media. This medium yielded 10 times the number of fungal colonies and 3 times the number of genera found on TSA pour plates as currently used for spacecraft assay.     

Effect of heat treatment on the performance of tryptose-sulfite-cycloserine agar for enumeration of Clostridium perfringens.

Dissolving dehydrated tryptose-sulfite-cycloserine agar by only boiling or microwaving was found to inhibit Clostridium perfringens colony development in pour plates when compared with C. perfringens recovery in tryptose-sulfite-cycloserine agar prepared by autoclaving.     

Effect of heat treatment on the performance of tryptose-sulfite-cycloserine agar for enumeration of Clostridium perfringens.

Dissolving dehydrated tryptose-sulfite-cycloserine agar by only boiling or microwaving was found to inhibit Clostridium perfringens colony development in pour plates when compared with C. perfringens recovery in tryptose-sulfite-cycloserine agar prepared by autoclaving.     

CAS平板覆盖法检测氢氧化细菌铁载体

【目的】用CAS平板覆盖法检测氢氧化细菌铁载体,解决通用CAS琼脂平板法中十六烷基三甲基溴化铵对真菌和某些细菌的生长抑制问题。【方法】将改良的CAS检测培养基覆盖在长满菌落的无铁培养基上,生长抑制问题因微生物未与十六烷基三甲基溴化铵直接接触而解决。【结果】3株氢氧化细菌SDW-5、SDW-9和AaP-13均能产生单菌落,加入CAS检测培养基1 h后,菌落周围产生明显的铁载体晕圈。【结论】本方法成功解决了生长抑制问题,可以作为检测微生物铁载体的通用方法。     

Colony formation of mammalian cells on agar plates and its application to Lederberg's replica plating

In this paper we describe a new technique of cloning by use of agar plates and its application to replica plating. It was found that most cell lines form colonies on the surface of solid agar, although the plating efficiency and size of colony is dependent on specimens and concentrations of agar and agarose used. When 0.5% Noble-agar was used as substrate, plating efficiencies were obtained comparable to those of conventional cloning techniques in liquid medium and of agar suspension cultures. In some cases, including the primary culture of Yoshida sarcoma, the efficiency of plating was apparently higher than that obtained by the already established procedures. In an experiment with a series of BHK-21 cells, it was found that virally transformed cells could form colonies on agar plate, whereas untransformed and reverted cells could not divide, suggesting that agar plate culture, as well as agar suspension culture, can be used for a selective assay of transformation.Two methods of replica plating were employed. Method I is that devised by Lederberg in which colonies on the master plate are imprinted on pile fabrics and then transferred to the replica plates. With FM3A cells, the fidelity of replica plating was around 95%. Method II is inoculation of clones by applying a glass rod to the replica plates on which positions of inocula were identified by a grid. Fidelity of replica plating of FM3A, L5178Y and YSC cells was 99.7, 100 and 100% respectively.