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Chitinolytic properties of Bacillus pabuli K1. pabuli芽孢杆菌K1的几丁质降解特性。
Pub Date : 1994-04-01 DOI: 10.1111/j.1365-2672.1994.tb01641.x
E Frändberg, J Schnürer

The chitinolytic properties of Bacillus pabuli K1 isolated from mouldy grain was studied. Chitinase activity was measured as the release of p-nitrophenol from p-nitrophenyl-N,N'-diacetylchitobiose. Influences of substrate concentration and different environmental variables on growth and chitinase activity were determined. The optimum environmental conditions for chitinase production were: 30 degrees C, initial pH 8, initial oxygen 10% and aw > 0.99. Chitinase production was induced when B. pabuli K1 was grown on colloidal chitin. The smallest chito-oligosaccharide able to induce chitinase production was N,N'-diacetylchitobiose, (GlcNAc)2. Production was also induced by (GlcNAc)3 and (GlcNAc)4. When the bacterium was grown on glucose or N-acetylglucosamine, no chitinases were formed. The highest chitinase production observed was obtained with colloidal chitin as substrate. The production of chitinases by B. pabuli K1 growing on chitin was repressed by high levels (0.6%) of glucose. The production was also repressed by 0.6% starch, laminarin and beta-glucan from barley and by glycerol. The addition of pectin and carboxymethyl cellulose increased chitinase production.

研究了从霉变谷物中分离得到的pabuli芽孢杆菌K1的几丁质降解特性。通过对硝基-N,N'-二乙酰壳聚糖释放对硝基苯酚来测定几丁质酶的活性。测定底物浓度和不同环境变量对几丁质酶活性和生长的影响。产几丁质酶的最佳环境条件为:30℃,初始pH 8,初始氧10%,aw > 0.99。在胶体几丁质上生长的pabuli K1诱导了几丁质酶的产生。能诱导几丁质酶产生的最小的壳寡糖是N,N'-二乙酰壳寡糖(GlcNAc)2。(GlcNAc)3和(GlcNAc)4也能诱导其产生。当细菌在葡萄糖或n -乙酰氨基葡萄糖上生长时,没有几丁质酶形成。以胶体几丁质为底物的几丁质酶产量最高。生长在几丁质上的B. pabuli K1产生几丁质酶受到高水平(0.6%)葡萄糖的抑制。0.6%的淀粉、大麦中的层粘连蛋白和β -葡聚糖以及甘油也抑制了产量。果胶和羧甲基纤维素的添加增加了几丁质酶的产量。
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引用次数: 75
Effect of substrate on the production of antifungal volatiles from Bacillus subtilis. 底物对枯草芽孢杆菌抗真菌挥发物产生的影响。
Pub Date : 1994-04-01 DOI: 10.1111/j.1365-2672.1994.tb01646.x
P J Fiddaman, S Rossall

An antibiotic-producing strain of Bacillus subtilis has been shown to produce potent antifungal volatiles (AFV). These volatiles are active against a range of fungal species and are produced on a range of growth media and in loam-based compost. In vitro antifungal volatile activity on nutrient agar is enhanced with the addition of D-glucose, complex carbohydrates and peptones. The addition of L-glucose led to significantly less AFV activity than comparable levels of D-glucose. Growth studies in liquid culture revealed that B. subtilis failed to grow in response to L-glucose. Further growth studies on solid media showed no clear correlation between enhanced bacterial growth and increases in in vitro AFV activity in response to supply of substrates. Low level AFV activity was also detected from oilseed rape roots inoculated with B. subtilis. Gas chromatography mass spectrometry headspace analysis of B. subtilis cultures grown on various substrates revealed common similarities between substrates promoting AFV activity, although it was not possible to isolate individual antifungal compounds.

一种产生抗生素的枯草芽孢杆菌菌株已被证明能产生有效的抗真菌挥发物(AFV)。这些挥发物对一系列真菌物种有活性,并在一系列生长介质和壤土堆肥中产生。在琼脂上添加d -葡萄糖、复合碳水化合物和蛋白胨增强了体外抗真菌挥发活性。与同等水平的d -葡萄糖相比,添加l -葡萄糖导致AFV活性显著降低。液体培养的生长研究表明,枯草芽孢杆菌在l -葡萄糖的作用下不能生长。在固体培养基上的进一步生长研究表明,细菌生长的增强与体外AFV活性的增加之间没有明显的相关性,这是对基质供应的反应。在接种枯草芽孢杆菌的油菜根部也检测到低水平的AFV活性。气相色谱-质谱顶空分析显示,在不同底物上生长的枯草芽孢杆菌培养物在促进AFV活性的底物之间存在共同的相似性,尽管不可能分离出单个抗真菌化合物。
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引用次数: 132
The effect of electron beam irradiation and modified pH on the survival and recovery of Escherichia coli. 电子束辐照和修饰pH对大肠杆菌存活和恢复的影响。
Pub Date : 1994-04-01 DOI: 10.1111/j.1365-2672.1994.tb01648.x
L M Fielding, P E Cook, A S Grandison

The severity of radiation processing can be reduced by combining irradiation with other treatments, such as low pH. An exponential phase culture of Escherichia coli was irradiated at doses of 0-2.4 kGy at pH values ranging between 7.0 and 4.0, in an enriched nutrient broth. At pH 4.3 and above there was no significant effect of lowering the pH prior to irradiation. At pH 4.13 and 4.0, a much higher level of cell death occurred compared with irradiation at pH 7.0. This synergistic effect was observed only when the pH was lowered before radiation processing.

通过将辐照与其他处理(如低pH)相结合,可以降低辐射处理的严重程度。在富含营养的肉汤中,以0-2.4 kGy的剂量在pH值7.0至4.0之间照射大肠杆菌的指数相培养。在pH为4.3及以上时,辐照前降低pH没有显著效果。在pH为4.13和4.0时,与pH为7.0时相比,细胞死亡的水平要高得多。这种协同效应只有在辐射处理前降低pH时才能观察到。
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引用次数: 6
Effect of sub-MIC antibiotics on the cell surface and extracellular virulence determinants of Pseudomonas cepacia. 亚mic抗生素对洋葱假单胞菌细胞表面和细胞外毒力决定因素的影响。
Pub Date : 1994-02-01 DOI: 10.1111/j.1365-2672.1994.tb01615.x
D McKenney, L Willcock, P A Trueman, D G Allison

The effects of sub-MICs of ciprofloxacin and tobramycin on the cell surface characteristics and extracellular virulence factors of Pseudomonas cepacia were evaluated. Cells were grown in batch culture under iron-deficient and iron-replete conditions. At sub-MIC levels that did not affect bacterial growth cell surface hydrophobicity decreased under both iron-replete and iron-depleted conditions with ciprofloxacin, but increased with tobramycin under iron-sufficient conditions. Exopolysaccharide synthesis, lipase production and siderophore production were all significantly increased by the presence of ciprofloxacin under both growth conditions. Outer membrane protein and lipopolysaccharide profiles were not affected by exposure to the two antibiotics.

研究了环丙沙星和妥布霉素亚mic对洋葱假单胞菌细胞表面特性和胞外毒力因子的影响。细胞在缺铁和补铁条件下分批培养。在亚mic水平下,不影响细菌生长的细胞表面疏水性在环丙沙星补铁和缺铁条件下均下降,但在铁充足条件下妥布霉素增加。在两种生长条件下,环丙沙星的存在均显著提高了胞外多糖的合成、脂肪酶的产量和铁载体的产量。外膜蛋白和脂多糖谱不受暴露于两种抗生素的影响。
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引用次数: 12
Unmodified and recombinant strains of Lactobacillus plantarum are rapidly lost from the rumen by protozoal predation. 未经修饰的和重组的植物乳杆菌菌株在瘤胃中被原生动物捕食而迅速消失。
Pub Date : 1994-02-01 DOI: 10.1111/j.1365-2672.1994.tb01605.x
R Sharp, G P Hazlewood, H J Gilbert, A G O'Donnell

A genetically-manipulated strain of Lactobacillus plantarum and the unmodified parent strain were introduced into the rumen of sheep at an initial inoculum level of 1 x 10(7) cfu ml-1 of rumen fluid. There were no significant differences between the viable counts of the two inoculants throughout a 24 h sampling period. The rates of loss were 0.36 and 0.29 h-1 (proportion of colony-forming units lost, measured over the first 2 h) for the parent strain and recombinant strain respectively, and within 24 h of inoculation neither of the strains were detectable in rumen fluid. Further experiments in vitro revealed that the inoculants persisted in sterile rumen fluid with a loss rate of 0.044 and 0.057 h-1 for the parent strain and the recombinant strain respectively. Incubations with rumen fluid alone, protozoa-free rumen fluid and protozoa-enriched rumen fluid revealed that protozoal predation was the most significant factor in the loss of the introduced population. The loss rates from protozoa-free rumen fluid were not significantly different (P < 0.05) from those observed in sterile rumen fluid.

以1 × 10(7) cfu ml-1的瘤胃液初始接种量,将植物乳杆菌基因修饰菌株和未修饰亲本菌株分别引入绵羊瘤胃。在24 h的采样周期内,两种接种剂的活菌数没有显著差异。亲本菌株和重组菌株的菌落损失率分别为0.36和0.29 h-1(在前2 h内测量的菌落形成单位损失比例),接种后24 h内瘤胃液中均未检测到这两种菌株。进一步的体外实验表明,接种剂在无菌瘤胃液中持续存在,亲本菌株和重组菌株的损失率分别为0.044和0.057 h-1。单独的瘤胃液、不含原生动物的瘤胃液和富含原生动物的瘤胃液孵育表明,原生动物的捕食是引入种群损失的最重要因素。无原生动物瘤胃液的损失率与无菌瘤胃液无显著差异(P < 0.05)。
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引用次数: 23
The safety of Bacillus species as insect vector control agents. 芽孢杆菌作为病媒控制剂的安全性。
Pub Date : 1994-02-01 DOI: 10.1111/j.1365-2672.1994.tb01604.x
F A Drobniewski
One of the success stories of international co-operation in the control of infectious diseases has been the World Health Organization’s (WHO) Onchocerciasis Control Programme (OCP) in West Africa; the use of Bacillus thuringienszs (BT) toxins has been an important component of the programme (Rurges 1981; Anon. 1987; Guillet 1990; Webb 1992; Drobniewski 1993a). Onchocerciasis, or ‘river blindness’, is a chronic filarial disease caused by the parasitic nematode worm Onchocerca volvulus, and is transmitted by blackflies of the Simulium genus. The WHO estimates that over 90 million people are at risk from acquiring the disease, that there is an overall prevalence of 18 million people and that 1 000 000 cases of blindness have been caused by onchocerciasis (Anon. 1987; Guillet 1990; Webb 1992; Drobniewski 1993) . I t is a significant preventable cause of blindness and two disease control strategies have been pursued by the OCP since its inception in 1974: (1) the identification and treatment of those with onchocerciasis; and ( 2 ) aerial larviciding of rivers to control the vector, Simulium damnosum. The core of vector control has been weekly larviciding with the chemical pesticides temephos, pyraclofos, permethrin, carbosulfan and the bacterial biological control agent, Bacillus thuringiensis var. isruelensas H 14 (BTI). Bacillus thuringiensis (BT) produces crystalline parasporal inclusions during sporulation which are pathogenic to insect larvae, and to dipteran larvae in particular for the var. israelensis strain (Goldberg and Margalit 1977 ; Thomas and Ellar 1983; Ellar et al. 1986; Anon. 1987; Hofte and
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引用次数: 36
Rapid identification using pyrolysis mass spectrometry and artificial neural networks of Propionibacterium acnes isolated from dogs. 热裂解质谱法和人工神经网络快速鉴定犬源痤疮丙酸杆菌。
Pub Date : 1994-02-01 DOI: 10.1111/j.1365-2672.1994.tb01607.x
R Goodacre, M J Neal, D B Kell, L W Greenham, W C Noble, R G Harvey

Curie-point pyrolysis mass spectra were obtained from reference Propionibacterium strains and canine isolates. Artificial neural networks (ANNs) were trained by supervised learning (with the back-propagation algorithm) to recognize these strains from their pyrolysis mass spectra; all the strains isolated from dogs were identified as human wild type P. acnes. This is an important nosological discovery, and demonstrates that the combination of pyrolysis mass spectrometry and ANNs provides an objective, rapid and accurate identification technique. Bacteria isolated from different biopsy specimens from the same dog were found to be separate strains of P. acnes, demonstrating a within-animal variation in microflora. The classification of the canine isolates by Kohonen artificial neural networks (KANNs) was compared with the classical multivariate techniques of canonical variates analysis and hierarchical cluster analysis, and found to give similar results. This is the first demonstration, within microbiology, of KANNs as an unsupervised clustering technique which has the potential to group pyrolysis mass spectra both automatically and relatively objectively.

获得了参考菌株丙酸杆菌和犬分离株的居里点热解质谱。通过监督学习(使用反向传播算法)训练人工神经网络(ann)从这些菌株的热解质谱中识别这些菌株;所有犬源分离株均鉴定为人类野生型痤疮假体。这是一项重要的分类学发现,表明热解质谱与人工神经网络的结合提供了一种客观、快速、准确的鉴定技术。从同一只狗的不同活检标本中分离出的细菌被发现是不同的痤疮假单胞杆菌菌株,这表明动物体内的微生物群存在差异。将Kohonen人工神经网络(kann)对犬分离物的分类与经典的多变量分析(canonical variate analysis)和层次聚类分析(hierarchical clustering analysis)进行比较,发现两者的分类结果相似。这是第一次证明,在微生物学中,kann作为一种无监督聚类技术,具有自动和相对客观地分组热解质谱的潜力。
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引用次数: 87
Isolation of Legionella from water samples using various culture methods. 不同培养方法从水样中分离军团菌。
Pub Date : 1994-02-01 DOI: 10.1111/j.1365-2672.1994.tb01611.x
J M Kusnetsov, H R Jousimies-Somer, A I Nevalainen, P J Martikainen

The efficacy of a non-selective medium and two selective media were compared for the isolation of legionellas from water samples. The effect of acid wash treatment for decontamination of the water samples on the isolation frequency of legionellas was also studied. The 236 samples were taken from cooling, humidifying and drinking water systems; 21% were legionella-positive when inoculated directly on modified Wadowsky-Yee (MWY) medium and 26% were positive when concentrated (x 200) before cultivation on MWY or CCVC media. Inoculation on MWY medium after concentration followed by decontamination by the acid-wash technique gave the highest isolation frequency (31%). The lowest frequency (8%) was found with the non-selective BCYE alpha medium. An isolation frequency of 28% was achieved with the BCYE alpha medium after concentration and acid-wash treatment of the samples. Forty per cent of the samples were positive for legionellas when the results from all the culture methods were combined. Not all the legionella-positive samples were identified by a single culture method. Ninety-three of the 95 positive samples were detected with the two best combinations of three culture methods. The best culture method for detecting legionellas depended on the source of the water sample. Some water quality characteristics, like temperature and organic matter content, affected the isolation frequency of Legionella spp.

比较了非选择培养基和两种选择培养基分离水样军团菌的效果。研究了酸洗净化水样对军团菌分离频率的影响。这236个样本取自冷却、加湿和饮用水系统;在改良Wadowsky-Yee (MWY)培养基上直接接种时军团菌阳性21%,在MWY或CCVC培养基上培养前浓缩(× 200)时阳性26%。浓缩后在MWY培养基上接种,再用酸洗技术去污,分离率最高(31%)。非选择性BCYE α培养基的发生率最低(8%)。对样品进行浓缩和酸洗处理后,BCYE α培养基的分离率为28%。当综合所有培养方法的结果时,40%的样品对军团菌呈阳性。并非所有军团菌阳性样本都能通过单一培养方法进行鉴定。95份阳性样品中有93份为3种培养方法的2种最佳组合。军团菌的最佳培养方法取决于水样的来源。水温、有机质含量等水质特征影响军团菌的分离频率。
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引用次数: 20
Physiological aspects of disinfection resistance in Pseudomonas cepacia. 洋葱假单胞菌消毒抗性的生理方面。
Pub Date : 1994-02-01 DOI: 10.1111/j.1365-2672.1994.tb01609.x
B H Pyle, S K Watters, G A McFeters

A Pseudomonas cepacia population was isolated which had reduced susceptibility to iodine and maintained resistance when subcultured several times in phosphate buffer. This population was also resistant to iodine after growth in a minimal medium containing glycerol but not glucose. Addition of cAMP to glucose-grown cells caused increased resistance to iodine. Iodine-resistant cultures also demonstrated reduced susceptibility to chlorination but not to heat or metals (Cu/Ag). The results indicate that halogen resistance can be expressed in varying degrees, dependent on the carbon source, and cAMP may promote this expression. Thus, a catabolite repression-like mechanism may cause resistant cultures grown in some media to become more sensitive to halogens.

分离出一株洋葱假单胞菌,在磷酸盐缓冲液中多次传代后,其对碘的敏感性降低,并保持抗性。在含有甘油但不含葡萄糖的最小培养基中生长后,该种群也对碘具有抗性。在葡萄糖生长的细胞中加入cAMP会增加对碘的抵抗力。抗碘培养也显示出对氯化的敏感性降低,但对热或金属(Cu/Ag)没有敏感性。结果表明,耐卤素基因的表达不同程度地依赖于碳源,cAMP可以促进这种表达。因此,分解代谢物抑制样机制可能导致在某些培养基中生长的抗性培养物对卤素更加敏感。
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引用次数: 18
Antimicrobial activity of shredded carrot extracts on food-borne bacteria and yeast. 胡萝卜丝提取物对食源性细菌和酵母菌的抑菌活性。
Pub Date : 1994-02-01 DOI: 10.1111/j.1365-2672.1994.tb01608.x
I Babic, C Nguyen-the, M J Amiot, S Aubert

Purified ethanolic extracts of peeled and shredded carrots showed an antimicrobial effect against a range of food-borne micro-organisms. The minimum inhibitory concentration, expressed as mg ml-1 dried carrot material used for the extraction were: Leuconostoc mesenteroides, 27; Listeria monocytogenes, > 27 < 55; Staphylococcus aureus, > 27 < 55; Pseudomonas fluorescens, > 55 < 110; Candida lambica, > 55 < 110; Escherichia coli, > 110 < 220. The antimicrobial activity was not linked to phenolic compounds but was presumably due to apolar components. Free saturated fatty acid (dodecanoic acid) and methyl esters of saturated fatty acids (of dodecanoic and pentadecanoic acids) were identified in purified active extracts of carrots by gas chromatography coupled to mass spectrometry and could be responsible for the antimicrobial activity. This effect did not seem to play a role in the resistance of shredded carrots to microbial spoilage, although the antimicrobial activity was present in fresh carrots at concentrations sufficient to inhibit spoilage bacteria.

去皮和切碎的胡萝卜的纯化乙醇提取物显示出对一系列食源性微生物的抗菌作用。最小抑制浓度,以mg ml-1表示,用于提取的干胡萝卜材料为:Leuconostoc mesenteroides, 27;单核增生李斯特菌,> 27 < 55;金黄色葡萄球菌,> 27 < 55;荧光假单胞菌,> 55 < 110;蓝念珠菌,> 55 < 110;大肠杆菌,> 110 < 220。抗菌活性与酚类化合物无关,但可能是由于极性成分。通过气相色谱-质谱联用技术鉴定了胡萝卜活性提取物中的游离饱和脂肪酸(十二烷酸)和饱和脂肪酸甲酯(十二烷酸和五烷酸),它们可能是胡萝卜抗菌活性的主要来源。尽管新鲜胡萝卜中的抗菌活性浓度足以抑制腐败细菌,但这种效应似乎并没有在胡萝卜丝对微生物腐败的抗性中发挥作用。
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引用次数: 52
期刊
The Journal of applied bacteriology
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