柿提取物对枯草芽孢杆菌的抑制作用

对经不同极性提取剂处理的柿子提取物进行抑菌活性分析、耐药性实验,并对其有效成分进行了初步鉴定。结果表明,柿子皮、蒂的抑菌活性高于果肉;脂溶性提取物具有良好的抗菌效果,其中正丁醇,乙酸乙酯部位有较好的抗菌效果;柿浆石油醚提液抑制枯草芽孢杆菌表现出了耐药性,但耐药性并不稳定。有效成分鉴定揭示柿子提取物中含有黄酮类、三萜类和可水解单宁。     

柿提取物对枯草芽孢杆菌的抑制作用

对经不同极性提取剂处理的柿子提取物进行抑菌活性分析、耐药性实验,并对其有效成分进行了初步鉴定。结果表明,柿子皮、蒂的抑菌活性高于果肉;脂溶性提取物具有良好的抗菌效果,其中正丁醇,乙酸乙酯部位有较好的抗菌效果;柿浆石油醚提液抑制枯草芽孢杆菌表现出了耐药性,但耐药性并不稳定。有效成分鉴定揭示柿子提取物中含有黄酮类、三萜类和可水解单宁。      

天然植物精油对枯草芽孢杆菌的抑制作用

为了研究天然植物精油对枯草芽孢杆菌的抑菌作用,采用倍比稀释法对8种植物精油(菊花、冬青、金盏花、八角茴香、香蜂草、佛手柑、茉莉和野番茄精油)的抑菌活性进行筛选。采用Box-Behnken响应面试验设计研究精油间可能存在的协同增效作用。绘制复配精油对枯草芽孢杆菌的生长曲线,以判断其抑菌特征。结果表明,当精油含量在1μL/mL内,除香蜂草精油、野番茄精油外,其余6种精油对枯草芽孢杆菌都有抑制活性。八角茴香精油(MIC=0.5μL/mL)的抑菌活性比常见防腐剂(尼泊金酯)还强。当冬青精油0.61μL/m L+菊花精油0.44μL/mL+金盏花精油0.24μL/mL+八角茴香精油0.17μL/mL,冬青精油0.5μL/mL、八角茴香精油0.13μL/mL时,菊花精油和金盏花精油存在协同增效作用。由枯草芽孢杆菌的生长曲线可知,复配精油主要抑制了枯草芽孢杆菌对数生长期的分裂和繁殖,使得活菌数明显下降,无法达到正常的生长高峰。     

枯草芽孢杆菌素延长香肠货架期的研究

研究了枯草芽孢杆菌B·C119代谢产生的细菌素对香肠中细菌的抑制作用,并与山梨酸钾的抑菌效果进行对照,对香肠进行感官指标、pH、菌落总数的测定。结果表明:枯草芽孢杆菌素能有效的抑制香肠中细菌的繁殖,从而延长香肠的货架期,并且效果要优于山梨酸钾。      

气体二氧化氯对苦荞麦表面枯草芽孢杆菌杀菌效果研究

采用气体二氧化氯为杀菌剂,以杀菌率为指标,对苦荞麦介质表面枯草芽孢杆菌进行灭菌试验。以二氧化氯浓度、杀菌时间、二者交互作用作为杀菌率影响因素设计正交试验,结果表明:各因素影响顺序为二氧化氯浓度、杀菌时间、二者交互作用;以二氧化氯浓度100 mg/L、杀菌时间40 min,作为气体二氧化氯对接种到苦荞麦介质表面枯草芽孢杆菌最优杀灭条件;其杀菌率可达99.94%。     

枯草芽孢杆菌发酵提取物对大肠杆菌的抑制作用

为探索枯草芽孢杆菌发酵提取物对大肠杆菌的抑菌效果及作用机理,利用倍半稀释法确定其对大肠杆菌的最小抑菌浓度,通过研究枯草芽孢杆菌发酵提取物对大肠杆菌生长曲线、细胞膜通透性以及细胞超微结构的影响,探讨提取物对大肠杆菌的抑制作用机理,同时对该提取物的化合物类型进行了初步分析。结果表明,该提取物对大肠杆菌具有明显的抑制作用,其最小抑菌浓度为0.614 mg·mL^-1,在大肠杆菌生长的延滞期和对数期加入该提取物,比在稳定期加入能够显现出更好的抑菌效果。经提取物作用后的细胞表面粗糙,边缘模糊,细胞膜破裂,表明该提取物能够增加大肠杆菌细胞膜的通透性。化合物分析显示,提取物中抑菌成分主要是多烯类化合物和脂肽类化合物。     

枯草芽孢杆菌素延长香肠货架期的研究

研究了枯草芽孢杆菌B.C119代谢产生的细菌素对香肠中细菌的抑制作用,并与山梨酸钾的抑菌效果进行对照,对香肠进行感官指标、pH、菌落总数的测定.结果表明:枯草芽孢杆菌素能有效的抑制香肠中细菌的繁殖,从而延长香肠的货架期,并且效果要优于山梨酸钾.     

枯草芽孢杆菌功能及相关机制研究进展

本研究首先从东北传统豆酱中分离筛选出一株具有良好抑菌作用的菌株,结合16S rDNA与持家基因gyrA测序分析等方法对菌株鉴定。其次,利用乙酸乙酯萃取法对其所产细菌素进行粗提,使用葡聚糖凝胶Sephadex-G50和高效液相色谱（HPLC）技术进一步纯化,结合SDS-PAGE和液相色谱-质谱联用（LC-MS/MS）技术进行鉴定。最后通过最小浓度实验与生长抑制曲线分析了细菌素对金黄色葡萄球菌的抑制效果,并探究了细菌素对热、酸碱和蛋白酶的稳定性。结果表明,枯草芽孢杆菌（Bacillus subtilis）菌株S1-2对金黄色葡萄球菌和单增李斯特氏菌抑菌效果最好,该菌株产生的细菌素经分离纯化鉴定为subtilosin A,分子量约为3 kDa,对金黄色葡萄球菌和单增李斯特氏菌有明显的抑制效果,对金黄色葡萄球菌的最小抑制浓度为0.625 mg/mL。该细菌素在20~80 ℃抑菌活性稳定,且在100~120 ℃仍表现出抑菌活性;对酸碱耐受性较高,经过pH为1、10的强酸强碱处理后仍表现出抑菌活性,在pH6.0~8.0的范围内表现出最高的抑菌活性;能够被蛋白酶K、胃蛋白酶、胰蛋白酶水解。综上,枯草芽孢杆菌S1-2与其产生的细菌素subtilosin A在食品生物防腐中具有较强的研究和应用潜力。

     

盐胁迫对枯草芽孢杆菌发酵代谢产物的影响

研究了盐胁迫对枯草芽孢杆菌主要代谢产物的影响。利用氨基酸自动分析仪和顶空固相微萃取-气质联用技术,检测盐胁迫条件下主要理化指标、氨基酸和挥发性成分的变化情况。高盐胁迫下停滞期结束后,细胞残糖消耗速率最大但菌体生长缓慢,乳酸含量合成和消耗速率最快;天冬氨酸积累量增加而丝氨酸减少,组氨酸和苯丙氨酸浓度基本不变;中间盐浓度刺激下3-羟基-2-丁酮积累量最大,其次为糠醛等小分子风味成分,乙酸乙烯酯、甲氧基异戊酸乙酯等仅在对照盐浓度发酵过程中检测到,存在周期短且含量较低,2,5-二甲基吡嗪和苯甲醛仅在盐胁迫环境中产生。高盐胁迫下基质消耗主要用来进行产物合成,而不是菌体生长,乳酸在细胞抗高渗胁迫过程中起重要作用;高盐胁迫刺激了草酰乙酸为前体的氨基酸代谢途径;渗透胁迫能够刺激枯草芽孢杆菌生成某些特定化合物的代谢途径的增强,从而深入了解高渗胁迫下细胞内代谢方向的变化。     

枯草芽孢杆菌在白酒生产中的应用

从江苏双沟酒业股份有限公司堆积醅中筛选得到3株耐高温细菌（S2007-9,S2007-13,S2007-16）,经鉴定皆为枯草芽孢杆菌。以这3株芽孢杆菌为基础分别制成麸曲,用HS-SPME联合GC-MS分析麸曲中挥发性成分,结果发现,3株芽孢杆菌制成的麸曲中吡嗪类化合物的含量相比阴性对照有显著升高,特别是四甲基吡嗪的含量升高最为显著,3种单菌株麸曲中四甲基吡嗪的含量分别是阴性对照中含量的30.25倍、26.85倍和38.53倍。芳香族化合物和酚类化合物也有显著升高。将3种单菌株麸曲应用到白酒生产中发现能增加白酒中吡嗪类化合物的含量,其中四甲基吡嗪的含量分别是阴性对照的5.99倍、4.70倍和3.67倍,同时也能降低白酒中醇类和酯类化合物的含量。     

Antimicrobial activity of torilin isolated from Torilis japonica fruit against Bacillus subtilis

ABSTRACT:  Torilis japonica fruit has been used in therapeutic antimicrobial treatments in Korea and China since ancient times, but there is still little information on the mechanism underlying this activity. We found that the ethanol extract of T. japonica fruit showed excellent antimicrobial activity against Bacillus subtilis ATCC 6633 spores and vegetative cells. The crude ethanol extract (75%) reduced the spore concentration by 3 log cycles and the vegetative cell concentration to lower than the detection level (reduction in spore concentration by more than 6 orders of magnitude) at a concentration of 1% (w/v). The ethanol extract of T. japonica fruit was fractionated into n -hexane (H) and a water layer. The active antimicrobial compound was isolated and purified from the hexane layer, and identified as torilin (5-[1-(acetyloxy)-1-methylethyl]-3,8-dimethyl-2-oxo-1,2,4,5,6,7,8,8a-octa-hydroazulen-6-yl(2 E )-2-methylbut-2-enoate; C₂₂H₃₂O₅). Torilin immediately reduced vegetative cells counts by 5 to 6 orders of magnitude, and reduced spores counts by 1 order of magnitude. The integrity of structures such as the inner, middle, and outer layers of the coat and the cortex, protoplast membrane, and core are vital to spores. Torilin functions as a surfactant with hydrophilic and hydrophobic properties related to denaturalization of various proteins. The distortion of coat proteins due to direct binding polar groups of spore coats with hydrophilic groups of torilin may be responsible for the observed rapid inactivation of bacterial spores.     

食源性致病菌风险评估研究进展

食源性致病菌是食源性疾病的首要病因, 由其引起的食源性疾病长期以来一直是食品安全的主要威胁, 尤其在发展中国家,形势更严峻, 应引起重视。食品安全风险评估在降低食品安全风险、保障食品安全中发挥的重要作用日益显著。本文对近年来国内外食源性致病菌风险评估的研究进展进行综述,介绍了风险评估实际应用过程中我国学者对国外模型构建的利用和优化, 并总结我国食源性致病菌风险评估中存在的问题, 为更好地开展食源性疾病监测和食源性致病菌风险评估提供参考。     

食品中食源性致病菌污染状况及其 监测技术研究进展

食源性致病菌通常以食物为载体, 最终导致人体发生急性、慢性中毒, 给人体健康和生命安全带来威胁。本文简述了我国目前食品中食源性致病菌污染情况及其来源与危害, 并对食品中食源性病原菌检测技术及发展趋势进行了分析与展望, 以期为食品中食源性致病菌的控制、监督和检测提供借鉴和参考。     

山楂果胶寡糖及其复合物对枯草杆菌的抗菌作用

由于独特的胶凝性和增粘稳定性而在食品添加剂领域表现出广泛用途的山楂果胶,其低分子的分解产物—山楂果胶寡糖对枯草芽孢杆菌具有很强的抗菌性。进一步对山楂果胶寡糖与其他天然食品添加剂进行复配后的抗菌性进行分析的结果表明,山楂果胶寡糖与乳酸钠的复合物与二者单独使用相比对枯草芽孢杆菌具有更强的抗菌作用,在pH=5的条件下,5mg/mL的山楂果胶寡糖与10mg/mL乳酸钠的复配物即可完全抑制枯草芽孢杆菌的生长,在天然食品防腐添加剂的开发利用领域表现出了良好的应用前景。      

Antimicrobial activity of reuterin in combination with nisin against food-borne pathogens

Antimicrobial activity of reuterin individually or in combination with nisin against different food-borne Gram-positive and Gram-negative pathogens in milk was investigated. Reuterin (8 AU/ml) exhibited bacteriostatic activity against Listeria monocytogenes, whereas its activity was slightly bactericidal against Staphylococcus aureus at 37 degrees C. Higher bactericidal activity was detected against Escherichia coli O157:H7, Salmonella choleraesuis subsp. choleraesuis, Yersinia enterocolitica, Aeromonas hydrophila subsp. hydrophila and Campylobacter jejuni. A significant synergistic effect on L. monocytogenes and a slight additive effect on S. aureus after 24 h at 37 degrees C were observed when reuterin was combined with nisin (100 IU/ml). The combination of reuterin with nisin did not enhance the antimicrobial effect of reuterin against Gram-negative pathogens.     

Antimicrobial activity of nanosilver-coated socks fabrics against foot pathogens

Nanotechnology can be used in engineering-desired textile attributes, such as fabric softness and durability in fibres, yarns and fabrics. Nanocoating the surface of socks is one approach to the production of highly active surfaces with UV blocking, antimicrobial and self-cleaning properties. Synthesis of silver nanoparticles in this project was carried out chemically by wet reduction method (Ag-chem) and biologically by using neem (Azadirachta indica) leaves (Ag-neem). The formation of silver nanoparticles was monitored by UV–visible spectroscopy, which revealed the surface plasmon resonance peak at 420?nm for Ag-chem and 430?nm for Ag-neem, and transmission electron microscopy, which showed nanoparticles of various shapes and sizes (～5–50?nm). Quantification of the prepared silver nanoparticles was done by atomic absorption spectroscopy, which revealed 0.044?M Ag⁺ and 0.042?M Ag⁺ ions in Ag-chem and Ag-neem, respectively. Coating of the socks fabrics (nylon and cotton) was carried out by exposing these fabrics to the prepared nanoparticle solutions on a gyratory shaker overnight. Antimicrobial activity of the Ag-chem and Ag-neem was carried out by performing minimum inhibitory concentration (MIC) and disc diffusion test against Sarcina lutea, an odour-producing organism, Klebsiella pnuemoniae, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and Candida albicans, organisms causing foot infections. P. aeruginosa and S. lutea were found to be most sensitive to either of the above preparations. Ag-chem was found to be more effective than Ag-neem. Nylon and cotton socks fabrics were coated with each of the above preparations. The antibacterial efficacy of the nanosilver-finished fabrics was checked by zone inhibition test, antibacterial test and wash fastness test. In both cases, coated nylon fabrics showed better antimicrobial activity than coated cotton fabrics. S. lutea and K. pneumoniae showed greater zones of inhibition than the other test organisms. Nylon fabric coated with Ag-chem and Ag-neem gave maximum reduction in viable count of all test organisms as compared to cotton fabrics. Higher reduction in the viable count of all test organisms was observed with Ag-chem-coated nylon fabrics. Thus, coating of the nylon socks fabric with silver nanoparticles can be used as an effective way to combat foot-borne pathogens and thereby reducing discomforts like foot odour, perspiration, complications due to diabetes, athlete’s foot, etc.     

10-HDA对枯草芽孢杆菌的抑菌机理研究

为了确定与分析10-羟基-2-癸烯酸（10-HDA）的抑菌性能及其作用机制,采用牛津杯法,倍半稀释法进行抑菌性能测定实验。以枯草芽孢杆菌为供试菌,采用凝胶阻滞实验及原子力显微镜观察10-HDA与菌体DNA结合情况,并采用DNA琼脂糖凝胶电泳观察10-HDA作用后菌体DNA含量的变化,以及10-HDA对菌体基因组PCR的影响。结果表明,10-HDA对多种病原细菌具有明显的抑制作用,表现出广谱抗菌活性,且抑菌效果随着10-HDA浓度的增加显著提高。其中,对枯草芽孢杆菌的最小抑菌浓度（MIC）为0.62 mg/mL。DNA琼脂糖凝胶电泳和原子力显微镜结果显示,当10-HDA浓度达到0.62 mg/mL时,菌体中基因组DNA的合成量明显减少,而且10-HDA与细菌基因组DNA紧密结合。对基因组DNA的PCR影响实验进一步证明,当PCR体系中10-HDA的浓度达到1.0 mg/mL时,DNA的合成被完全阻碍。通过实验,我们得出10-HDA通过与细菌基因组DNA的结合,进一步阻碍DNA的合成,最终达到抑菌效果。     

等温扩增技术在食源性致病菌检测中的应用进展

等温扩增技术是近年来迅速发展的一类核酸扩增技术。相比于PCR,该技术具有高特异性、高敏感性、简单、便捷及低成本的特点。目前,核酸等温扩增技术在感染性疾病的诊断、基因多态性分析、疫情防治等方面已经有广泛应用,也有文献报道了其在细菌、病毒等病原体检测方面的应用。食源性致病菌和环境中的病原体检测等领域中,等温扩增技术展现了广阔的应用潜力,有望发展成为食源性致病菌检测的重要方法。本文综合国内外文献报道,对环介导等温扩增、依赖解旋酶等温扩增、依赖核酸序列等温扩增、切刻内切酶核酸恒温扩增、交叉引物等温扩增、链置换等温扩增、SmartAmp技术等一系列等温扩增技术的原理、特性及其在食源性致病菌检测中的应用情况做一综述,从而为该技术在食源性致病菌检测的实际应用中提供参考和依据。     

枯草芽孢杆菌SH7 抑菌蛋白的分离纯化及对烟草青枯病菌的抑制作用

采用硫酸铵分级沉淀、DEAE Sepharose Fast Flow 离子交换层析、Sephadex G-75 凝胶层析及聚丙烯凝胶电泳,从 枯草芽孢杆菌SH7 代谢物中分离纯化出一种相对分子质量为33.6 kD 的蛋白,该活性物质具有淀粉酶活力,对烟草青枯病菌 具有一定的抑制作用。     

带自身启动子的bgaB基因在枯草芽孢杆菌中的表达

将来源于嗜热脂肪芽孢杆菌的启动子连同β-半乳糖苷酶bgaB基因经PCR扩增后,连接在T载体上,再取代枯草杆菌载体pZ01-bgaB的启动子,将其在枯草杆菌宿主WB600中表达.经摇瓶发酵20h,得到乳糖酶活力6.37U/mL,比活力3.814U/mg,SDS-PAGE电泳显示有明显重组蛋白质条带.证明了嗜热脂肪芽孢杆菌来源的启动子在枯草杆菌中是完全适用的.