荷叶黄酮对食源性致病菌的抑菌活性初步研究

目的比较荷叶黄酮对不同食源性致病菌的抑菌活性。方法从干荷叶中提取荷叶黄酮,选择3种食源性致病菌进行抑菌试验,并获得最小抑菌浓度(MIC);同时对荷叶黄酮的抑菌活性的热稳定性及p H稳定性进行分析。结果从干荷叶中提取出15%荷叶黄酮粗提干粉,抑菌试验证实食源性致病菌蜡样芽胞杆菌MS10362R、枯草芽胞杆菌subsp.subtilis str.168和福氏志贺菌CDC1对荷叶黄酮的作用较为敏感,并且具有显著的浓度依赖性,其MIC分别为1.0、1.5和3.5 mg/m L。不同的热处理(50~90℃)对荷叶黄酮的抑菌活性影响较小,其在90℃处理后对蜡样芽胞杆菌、枯草芽胞杆菌和福氏志贺菌的抑菌活性分别降低了35.89%、23.86%和28.72%。随着p H的升高(p H 5.0~9.0),荷叶黄酮的抑菌活性呈现先升后降的趋势,但变化不大,在中性偏碱的溶液环境中抑菌活性较高。结论荷叶黄酮抑菌活性稳定,可作为食品添加剂开发,具有潜在的应用潜力。     

虫草素的抑菌活性及机理研究

虫草素为蛹虫草等食药保健品的主要活性成分.为进一步评价分析虫草素的抑菌活性及机理,通过最低抑菌浓度及抑菌圈实验测定、扫描电镜观察虫草素对6种常见细菌的抑菌谱及效果,测定供试菌的生长曲线、胞内紫外吸收物质泄露和菌体形态变化,分析虫草素抑制菌体生长及破坏细胞结构机理.结果表明,在溶解度范围内虫草素对3种G+菌有明显抑菌效果...     

苦楝素联合BIT对白色念珠菌的协同抑菌效果研究

探讨苦楝素与BIT分别单独及二者联合使用对白色念珠菌的浮游菌生长及其生物膜形成的影响。以预加菌液倾注平板打孔抑菌实验法测定苦楝素、BIT及二者联合使用对白色念珠菌菌体生长的抑制效果,96孔板微量稀释法培养该菌浮游菌及其生物膜,分别测定浮游菌及其生物膜的吸光度并进行比较分析,判断最小抑菌浓度(MIC),计算二者联合时的抑菌指数(FIC)。平板打孔抑菌实验结果显示,其抑菌效果依次为:二者联合BIT苦楝素;96孔微量稀释法结果显示:二者联合的FIC系数为0.75;二者联合抑制该浮游菌生长比单用时药效增加了20%～50%,抑制其生物膜的形成比单用时药效增加了33%～50%。苦楝素与BIT联合使用具有对白色念珠菌生长的复配增效抑制作用,不但有效抑制该菌浮游菌生长,也能抑制其生物膜的形成。     

红谷霉素对细菌抑制效果研究

红谷霉素是链霉菌702发酵后所产的一种生物活性物质,具有较强抗细菌活性。研究表明,红谷霉素对大肠杆菌的最低抑菌浓度为40mg/L,对枯草芽胞杆菌的最低抑菌浓度为0.08mg/L。红谷霉素在微生物生长迟滞期添加比在其它生长阶段添加抑菌效果更好,红谷霉素对热和紫外比较稳定。通过与其他防腐剂的抑菌效果比较表明,红谷霉素对细菌的抑菌效果优于比较的防腐剂。     

影响多粘类芽胞杆菌发酵液抑菌活性因素的研究

目的以点青霉菌作为指示菌,研究影响植物内生多粘芽胞杆菌发酵液抑菌活性的部分因素,为鉴定发酵液的抑菌物质提供基础研究。方法通过对多粘类芽胞杆菌发酵液进行不同处理（改变pH、加热、乙醇处理和蛋白酶酶解）,采用牛津杯法观察处理后发酵液对点青霉菌抑菌活性的变化。结果多粘类芽胞杆菌发酵液的抑菌效果在酸性条件下稳定,抑菌效果明显;而在中性和碱性范围内不稳定,抑菌效果不明显;多粘类芽胞杆菌发酵液中的有些抑菌物质具备良好的热稳定性;80％乙醇处理的发酵上清液有抑菌作用;经蛋白酶酶解后发酵液的抑菌活性变化不大。结论多粘类芽胞杆菌产生的乙醇沉淀物具有抑菌作用;发酵液中可能含有类细菌素的抑菌物质。     

解淀粉芽胞杆菌BaX030的分离鉴定及抗菌功能

摘要:【目的】芽胞杆菌是微生物活性物的重要来源,从全国各地采集的72份土壤样品中分离出339株芽胞杆菌,研究各菌株抑菌活性,分离纯化抑菌活性物,为丰富芽胞杆菌菌种资源和微生物次级代谢物的挖掘奠定实际应用基础。【方法】采用水浴加热和稀释平板涂布等方法从河南花生地采集的土壤中筛选得到一株具有很强抑菌活性的芽胞杆菌,结合形态观察、生理生化特征和16S rRNA基因序列同源性比对分析,对该菌株进行鉴定。丙酮沉淀、葡聚糖凝胶柱层析、C18反相柱层析得到Bacillus amyloliquefaciens X030抑菌活性物,LC-MS/MS鉴定其分子量。利用滤纸片扩散法和平板对峙培养法测定抑菌谱及拮抗性质。【结果】筛选分离得到一株解淀粉芽胞杆菌,归类并命名为解淀粉芽胞杆菌Bacillus amyloliquefaciens X030。BaX030对金黄色葡萄球菌(Staphylococcus aureus)、白色念珠菌(Candida albicans)、酵母菌( Saccharomycetes)有较强抑制效果,对水稻稻瘟病菌(Pyriculariaoryzae)、辣椒尖胞炭疽病菌(Chili pointed cell anthrax)、枇杷炭疽病菌(Gloeosporium eriobotryae speg)、烟草黑胫病菌(Phytophthora parasitica)有良好拮抗活性。初步确定BaX030产生的抑菌活性物为多肽类化合物。【结论】分离得到的B． amyloliquefaciens X030产生了一个对病原细菌具有较强抑制作用的多肽,同时该菌株在拮抗植物病原真菌方面也有明显的效果。     

芽胞杆菌抗菌活性和纤维素酶活性的测定

目的筛选鸡用益生菌。方法通过牛津杯法、混菌法和DNS分光光度法对从鸡肠道分离的10株芽胞杆菌进行抑菌效果及纤维素酶活性测定。结果编号为Y1、Y5、Y7的3株芽胞杆菌对测试菌具有较好抑菌效果,编号为Y2、Y4、Y5的3株芽胞杆菌具有较高的产酶活性。结论从分离的10株芽胞杆菌中筛选出1株（编号为Y5）兼具较好抑菌效果和较高产酶活性的地衣芽胞杆菌,具有作为饲用益生菌开发的潜能。     

香兰素的抑菌性及其应用的初步研究

通过平板涂布法研究了香兰素对细菌、酵母菌及霉菌的抑制作用。结果表明,香兰素有较强的抑菌性,对大肠埃希菌的最低抑制浓度（MIC）为0.23%,枯草芽胞杆菌为0.26%,酵母菌为0.14%,黑根霉和毛霉分别为0.14%和0.03%。香兰素经80℃、60 min处理后不影响其对细菌、黑根霉等的抑制效果。将其应用于打开了包装的牛奶中,研究发现,当温度为4℃,香兰素浓度仅为0.05%,即可产生良好的抑菌效果,使牛奶的保质期延长至4～5 d。     

顺反式肉桂醛对肉源隆德假单胞菌生物被膜和致腐性的抑制作用

【目的】为比较反式和顺式肉桂醛对肉源假单胞菌生物被膜和致腐性的影响。【方法】通过平板计数测定两种肉桂醛对隆德假单胞菌的最小抑菌浓度(MIC),结晶紫法、珠涡流法、激光共聚焦显微镜观察、福林法等检测亚抑菌浓度肉桂醛处理下隆德假单胞菌生物被膜形成、运动性和胞外酶活性变化。荧光定量RT-PCR检测肉桂醛对隆德假单胞菌粘附lapA、鞭毛fliC、蛋白酶aprX和脂肪酶lip基因表达量的影响。【结果】反式和顺式肉桂醛对隆德假单胞菌的MIC分别为200μg/mL和225μg/mL,1/8 MIC、1/4MIC、1/2MIC亚抑菌浓度肉桂醛显著降低隆德假单胞菌生物被膜结晶紫和粘附性,其中1/2MIC反式和顺式肉桂醛处理下被膜分别减少60.27%和52.05%,菌体粘附降低56.35%和61.10%。亚抑菌浓度肉桂醛显著减少被膜厚度,反式肉桂醛还能显著杀灭被膜菌。且肉桂醛能显著抑制菌体的泳动性,反式肉桂醛对生物被膜和泳动性的抑制效果更强。肉桂醛还能抑制隆德假单胞菌蛋白酶和脂肪酶活性,其中1/2MIC反式和顺式肉桂醛处理下菌体蛋白酶分别减少61.90%和76.19%,脂肪酶降低40.17%和47.01%。且发现肉桂醛显著降低lapA、fliC、aprX和lip表达量,其中1/2MIC反式和顺式肉桂醛分别降低4个基因表达量至对照组的0.05–0.16和0.02–0.12倍。【结论】两种亚抑菌浓度肉桂醛异构体显著抑制隆德假单胞菌生物被膜和致腐性,其中反式肉桂醛对生物被膜抑制较强,而顺式肉桂醛更有效地降低致腐酶活性,其与肉桂醛下调相应基因表达密切相关。     

鸡源益生芽胞杆菌的筛选

根据菌体对低pH和高胆盐的耐受性、产酶特性和对病原菌的抑菌效果,对家鸡肠道中的芽胞杆菌进行了筛选。结果表明,有4株芽胞杆菌(A2、C5、C19和D8)能抑制金黄色葡萄球菌(Staphylococcus aureus)的生长。这4株菌在pH 3.0和高胆盐条件下的存活率都达到60%以上,产淀粉酶和蛋白酶的能力也较好,表明这些菌株具有作为益生菌的开发潜力。经形态学和生理生化反应鉴定,初步确定A2和D8为地衣芽胞杆菌(Bacillus licheniform is),C5和C19为蜡样芽胞杆菌(Bacillus cereus)。     

Effect of spore concentration on germination and autotropism inTrichoderma hamatum

Summary The effect of spore concentration on spore germination and germtube growth ofTrichoderma hamatum on water agar and on potato dextrose agar (PDA) was studied. Increasing inoculum size up to 10⁹ spores/plate on PDA and up to 10⁷ spores/plate on water agar shortened the incubation period required for germtubes emergence and increased germination rate. However, on water agar germination was inhibited at 10⁸ and was completely arrested at 10⁹ spores/plate. Inhibition in germination of 10⁷ spores/plate was observed on water agar when the plates were preincubated with 10⁹ spores/plate for 5 h or more. Addition of glucose and ammonium nitrate to the water agar medium allowed only 25% of the spores to germinate at 10⁹ as compared to 78% at 10⁷ spores/plate after 8 h of incubation. Addition of polysaccharides to the C+N supplemented medium, significantly increased germination up to 84% as compared to 100% on PDA, after 8 h of incubation. Germlings ofTrichoderma hamatum phialospores exhibited positive autotropism and anastamosis on both media. The phenomenon was positively related to inoculum size, being most pronounced at 10⁷ spores/plate.     

同步辐射软X射线对枯草杆菌的诱变效应

采用同步辐射软X射线对枯草芽孢杆菌(Bacillus subtilis)1831菌株进行辐照处理,研究了不同剂量下3．1nm的软X射线对其芽孢的失活和诱变作用。结果表明：同步辐射软X射线对枯草杆菌芽孢的剂量存活曲线表现为典型的“肩型”,对芽孢的失活作用属于“单靶多击”方式,失活击中数等于3。根据脱脂牛奶平板上蛋白酶活力大小的测量统计,以变异系数作为诱变效应指标,软X射线对芽孢具有一定的诱变作用。     

Germination and outgrowth of Schizosaccharomyces pombe ascospores isolated by Urografin density gradient centrifugation.

A simple method for the isolation of single ascospores of the fission yeast Schizosaccharomyces pombe was examined. Single spores in the 7-day-old sporulating culture of a homothallic strain were separated from remaining vegetative cells by isopycnic centrifugation in the linear gradient from 10 to 60% of Urografin solution at 700 X g for 20 min. Protein content of isolated spores was very low as compared with that of vegetative cells. The isolated spores germinated through the following steps when cultured in a liquid medium at 25--35 degrees C; loss of refractility (darkening) under a phase-contrast microscope, spherical growth (swelling), emergence of germ tubes, elongation of germ tubes, cell plate formation, and cell separation. The absorbance at 650 nm of the spore suspension initially decreased, accompanied by darkening of spores, and then increased with spherical growth. The germination rate of isolated spores reached almost 100%.     

Mass production of spores of lactic acid‐producing Rhizopus oryzae NBRC 5384 on agar plate

Mass production of sporangiospores (spores) of Rhizopus oryzae NBRC 5384 (identical to NRRL 395 and ATCC 9363) on potato‐dextrose‐agar medium was studied aiming at starting its L (+)‐lactic acid fermentation directly from spore inoculation. Various parameters including harvest time, sowed spore density, size of agar plate, height of air space, and incubation mode of plate (agar‐on‐bottom or agar‐on‐top) were studied. Ordinarily used shallow Petri dishes were found out to be unsuitable for the full growth of R. oryzae sporangiophores. In a very wide range of the sowed spore density, the smaller it was, the greater the number of the harvested spores was. It was also interesting to find out that R. oryzae grown downward vertically with a deep air space in an agar‐on‐top mode gave larger amount of spores than in an agar‐on‐bottom mode at 30°C for 7‐day cultivation. Scale‐up of the agar plate culture from 26.4 to 292 cm² was studied, resulting in the proportional relationship between the number of the harvested spores/plate and the plate area in the deep Petri dishes. The number of plates of 50 cm in diameter needed for 100 m³ industrial submerged fermentation started directly from 2 × 10⁵ spores/mL inoculum size was estimated as about 6, from which it was inferred that such a fermentation would be feasible. Designing a 50 cm plate and a method of spreading and collecting the spores were suggested. Bioprocess technological significance of the “full‐scale industrial submerged fermentation started directly from spore inoculation omitting pre‐culture” has been discussed. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:876–881, 2013     

Regulation of formation of aerial mycelia and spores of Streptomyces viridochromogenes.

Growth of Streptomyces viridochromogenes on a solid glycerol-NH4NO3 salts medium was accompanied by the formation of aerial mycelia and spores. Adding 0.5% or more casein hydrolysate to the medium stimulated growth while completely repressing the formation of aerial mycelia and spores. This repression was temporary, as evidenced by the fact that transfer of the organisms to media not containing casein hydrolysate resulted in the appearance of aerial mycelia and spores. The effects of individual amino acids were tested. Glycine retarded growth and repressed formation of both aerial mycelia and spores. L-Aspartic acid, L-glutamic acid, and L-histidine stimulated or had little effect on growth and repressed formation of spores but not aerial mycelia. Repression by casein hydrolysate could not be attributed to the carbon/nitrogen ratio or the pH of the medium. Adding 1.25 to 2.5 mM adenine to the medium caused a reversal of the casein hydrolysate repression of aerial mycelium formation but did not reverse repression of sporulation. Dimethyladenine and 8-azaguanine had an effect similar to that of adenine, but a variety of other purine or pyrimidine derivatives had no effect on casein hydrolysate repression. The repression of aerial mycelium and spore formation by casein hydrolysate occurred only in media containing 15 mM or more phosphate. Aerial mycelia and spores were formed in media containing casein hydrolysate and 3 mM or less phosphate.     

Reaction of the soil microflora after contamination with chlorinated aromatic compounds and HCH

Abstract The effect of the pollution of an industrial land site with chlorinated benzenes, chlorinated phenols, hexachlorocyclohexane-isomers (HCH) on the soil microflora was investigated. Cell counts (microscopic and by plate count) as well as respiration rated did not correlate negatively with the concentration of the contaminants. Soil microorganisms grew in the presence of up to 750 μmol 1⁻¹ pf chlorinated compounds in liquid culture. Only 150 μmol l⁻¹ 2,4,5-trichlorophenol (2,4,5-TCP) inhibited growth totally. In enrichment cultures, bacteria used α- and γ-HCH, 3-chlorophenol (3-CP), 2,3-dichlorophenol (2,3-DCP), 2,6-DCP, 2,4,5-TCP, and 1,2,4,5-tetrachlorobenzene (1,2,4,5-TeCB) as a sole source of carbon and energy under aerobic conditions. No growth was observed with β-HCH. Under anaerobic conditions no growth was observed with any of the substances tested     

Interferon (IFN) alpha inhibits cell proliferation of UWOV2 cells without down-regulation of transferrin receptors.

It has been suggested that growth inhibition of cells by interferons may be mediated through interferon induced down-regulation of transferrin receptor expression. We describe a continuously growing cell line UWOV2 (pf) which expresses cell surface transferrin receptor but is able to grow in the absence of transferrin. This cell line is sensitive to the growth inhibitory effects of interferon alpha. Interferon alpha induced growth inhibition is not, however, accompanied by modulation of transferrin receptor expression suggesting that transferrin receptor modulation is not an essential component of the growth inhibitory effect of interferons.     

The survival of micromycetes and yeasts under the low-temperature plasma generated in electrical discharge

The fungicidal effect of low-temperature plasma generated by positive direct current discharge and its influence on the growth dynamics was evaluated on three micromycete species and yeast in water suspensions. The fungicidal effect was lower than analogous bactericidal effect and differs substantially among various fungal species. Together with the cidal effects, the slower growth of exposed fungal spores was observed.     

Use of Epifluorescence Microscopy in Studies of the Germination and Recovery of Thermoactinomycetes

Spore germination and growth of thermoactinomycetes were observed by epifluorescence microscopy. Each of the principal stages in germination was recognized and found to correspond to changes in phase-contrast appearance commonly monitored during endospore germination. The effects of novobiocin and nalidixic acid on germination of Thermoactinomyces vulgaris and T. thalpophilus were studied by using epifluorescence microscopy. Outgrowth but not initiation was inhibited by 100 μg of nalidixic acid per ml and 50 μg of novobiocin per ml. When each of the compounds, at various concentrations, was incorporated into a medium for thermoactinomycete recovery, the antibiotics were found to inhibit colony development. Samples of water and sediment incubated in a growth medium containing novobiocin and selective for thermoactinomycete species were examined by epifluorescence microscopy for total numbers of outgrown spores. Direct viable counts of outgrown spores indicated that the standard plate count enumerated less than 10% of the viable population of thermoactinomycetes.     

Airborne fungal spores in an industrial area: seasonal and diurnal periodicity

Qualitative and quantitative studies of atmospheric fungal spores at a chloralkali factory, Jayashree Chemicals. were made during 1993 employing culture plate and rotorod methods. A total of 57 sporulating fungal types, including three sterile mycelial forms, were recorded by the culture plate method and 51 spore types, including the hyphal fragments and unidentified spores, were recorded by the rotorod method. As to the seasonal variation, winter was found to be the greatest contributor of fungal spores as compared to the summer and rainy season. Instead, when considering the hour of the day, the peak number of fungal propagules was recorded at noon (12.00 h) followed by evening and morning values, an exception being recorded in winter months, when maximum CFUs ofCladosporium were monitored in the morning. The seasonal variation in fungal concentration and composition was found to be influenced by temperature, rainfall and relative humidity, whereas diurnal incidence was the effect of varying temperature and relative humidity during day time only. Moderate temperature and relative humidity favoured the maximum fungal spore load in the atmosphere.Cladosporium, Nigrospora, Alternaria, Lasiodiplodia, Drechslera, Pestalotia, Curvularia, Epicoccum, Aspergillus, Penicillium andChaetomium were the commonest fungal spores in the factory area.