生防绿色木霉M1M2的生物学特性及抑菌研究

为进一步开发利用生防绿色木霉菌M1M2,研究了木霉菌菌株M1M2的最适培养基、温度、光照、pH及其分生孢子的致死温度,并采用平皿对峙培养法测定了其对6种病原菌的抑菌率。结果表明:M1M2最适培养基为糖浆培养基,最适生长和产孢条件为温度25~30℃,pH 5,24h全光照,其分生孢子致死温度为52℃;对向日葵黄萎病菌、马铃薯立枯丝核病菌、番茄灰霉病菌和大豆菌核病菌的抑菌率为100%。     

乳酸菌对中草药的发酵及抑菌活性检测

选择13株性能良好的乳酸菌对5味抗菌、抗病毒中草药(板蓝根、甘草、陈皮、苦丁、苦藠)进行发酵,检测发酵产物对大肠杆菌、沙门氏菌、金黄色葡萄球菌的抗菌活性。结果显示,乳酸菌在5味中草药中均能生长,每种中草药均有最适发酵菌株;抑菌试验表明,不同的乳酸菌菌株发酵5味中草药表现出不同的抑菌能力,罗伊氏乳杆菌发酵板蓝根、陈皮、苦丁、苦藠的上清液对大肠杆菌、沙门氏菌、金黄色葡萄球菌都具有显著的抑菌效果,甘草被发酵后基本无抑菌活性。     

抗菌肽基因异源表达系统研究进展

抗菌肽是机体天然免疫系统的重要组成部分,因具有抗菌谱广、活性稳定、不易产生耐药性等优点而在食品、饲料、农业、医药领域具有重要的应用价值.由于化学合成的成本较高,利用基因工程技术构建高效的生物表达系统成为一个新的途径.综述了抗菌肽在细菌、酵母、植物、动物等表达系统中异源表达的研究进展,为抗菌肽的研究应用提供理论依据.     

1株链霉菌BCG36的鉴定及抗菌活性研究

对分离自广西北海红树林根际土壤中的l株放线菌BCG36进行抗菌活性及生理生化特性的研究,并对其进行16S rDNA序列分析.结果显示:放线菌BCG36革兰氏染色呈阳性;有淀粉酶、纤维素酶、脂肪酶活性;牛奶先凝固后冻化,可使硝酸盐还原,不产硫化氢,不产黑色素,不使明胶液化;对大肠埃希菌、普通变形杆菌、乙型溶血性链球菌、金黄色葡萄球菌和白假丝酵母菌均有较好的抑制作用.16SrDNA测序后比对显示,放线菌BCG36菌株属于链霉菌属(Streptomyces).     

东莞与邻近地区土沉香居群的叶形态 和遗传多样性分析

利用ISSR 技术分析了土沉香也Aquilaria sinensis（Lour.）Gilg.页4 居群的遗传多样性及遗传分化。应用9 条 引物从4 个居群共221 份样品中共扩增出105 个位点,其中多态性位点为104 个,多态位点百分率（PPB%）为 99.05%。等位基因数（Na）和有效等位基因数（Ne）分别为1.9905 和1.5854;Nei爷s 基因多样性指数（H）为0.3390, Shannon 信息指数（I）为0.5054,表明土沉香种内存在较丰富的遗传多样性。土沉香4 个居群总的遗传变异（Ht）为 0.3236,居群内的遗传变异（Hs）为0.2500,居群间的遗传分化系数（Gst）为0.2274,基因流（Nm）为1.6983。UPGMA 聚 类分析结果显示,电白居群和大岭山居群优先聚类,然后再与清溪居群聚类,而广西居群与其余3 个居群明显分离, 显示出较大的遗传分化;电白居群的大叶类群的分化大于小叶类群;东莞大岭山小叶类群与电白居群遗传相似性较 高,而大岭山大叶类群与清溪居群的遗传相似性较高。基于该研究结果,认为东莞大岭山居群部分来自清溪自然居 群,部分与电白居群来源相同,它们均来源于海南。     

The effect of piscidin antimicrobial peptides on the formation of Gram-negative bacterial biofilms

Fish-derived antimicrobial peptides are an important part of the innate immune system due to their potent antimicrobial properties. Piscidins are a class of antimicrobial peptides first described in hybrid striped bass (Morone chrysops x Morone saxatilis) but have also been identified in many other fish species. Previous work demonstrated the broad antimicrobial activity of piscidins against Gram-negative and Gram-positive bacterial species. This study sought to determine the extent to which class I (striped bass piscidin 1, white bass piscidin 1 and striped bass/white bass piscidin 3) and class II (striped bass piscidin 4 and white bass piscidin 5) piscidins inhibit biofilm formation of different Gram-negative bacteria. In general, the class I and II piscidins demonstrate potent activity against Escherichia coli and Flavobacterium columnare biofilms. The class II piscidins showed more activity against E. coli and F. columnare isolates than did the class I piscidins. The piscidins in general were much less effective against inhibiting Aeromonas hydrophila and A. veronii biofilm growth. Only the class I piscidins showed significant growth inhibition among the Aeromonas spp. examined.     

Extension of shelf life of tuberose flowers using a combination of gamma irradiation and generally regarded as safe (GRAS) preservatives and assessment of antimicrobial potency of senesced flowers

Tuberose cut flowers, available as loose flowers, were treated with gamma (γ) irradiation and generally regarded as safe (GRAS) preservative solutions for extension of shelf life. The flowers were packaged in low-density polyethylene bags, heat sealed and stored at 23 ± 2°C, 80% relative humidity (RH) and 4 ± 1°C, 40% RH, respectively. The flowers stored at these two temperature regimes were subjected to sensory evaluation and biochemical analyses. From these assessments, the longest shelf life of tuberose flowers was found to be 8 days at 23 ± 2°C, 80% RH (compared to 4 days for control) and 24 days at 4 ± 1°C, 40% RH (compared to 8 days for control) using combination treatment of low dose γ-irradiation (0.02 kGy) and preservative solutions (4% sucrose and 0.02% CaCl₂). Ethanolic extract of tuberose flowers of the most shelf stable set (stored at 4 ± 1°C), i.e. at the end of 24 days, showed antimicrobial potency against the common skin pathogen Staphylococcus aureus (ATCC 25923 and MDR strains), suggesting utility of the senesced tuberose flowers for therapeutic applications. This preservation technique would promote export of tuberose flowers by extension of their shelf lives and allow utilization of these flowers, post senescence.     

菊科植物蓬蒿提取物抑菌活性研究

以菊科蓬蒿属蓬蒿为试材,研究了水、50％乙醇和100％乙醇3种蓬蒿浸提物对灰葡萄孢菌、链格孢菌和黑根霉菌的孢子萌发和菌丝生长的影响.结果表明:蓬蒿提取物对灰葡萄孢菌和黑根霉菌的菌丝生长和孢子萌发具有较好的抑制作用,对链格孢菌的菌丝生长和孢子萌发的抑制作用不明显；对于灰葡萄孢菌,蓬蒿乙醇提取物对菌丝生长和孢子萌发的抑制作用大于水提物；黑根霉表现与其相反,水提取物比乙醇提取物对菌丝生长和孢子萌发的抑制作用更明显.     

动物大肠杆菌耐药性的变化趋势

本试验对50年代至90年代初分离保存的50株大肠杆菌进行了药物敏感性测定。结果表明，随着时间的推移，菌株对15种抗菌药物的耐性呈现不同程度的上升趋势，50年代的大肠杆菌分离株对15种抗菌药物均敏感，60年代的分离株对链霉素、四环素产生耐药，70年代对氨苄西林、氯霉素、磺胺甲基异唑、四环素、链霉素、甲氧苄胺嘧啶6种抗生素产生耐药，80年代至90年代初对阿莫西林／奥格门丁、庆大霉素、卡那霉素、萘啶酸、头孢噻吩、氨苄西林、氯霉素、磺胺甲基异唑、四环素、链霉素、甲氧苄胺嘧啶11种抗生素产生耐药，菌株的多重耐药性呈上升趋势。     

生物防腐剂及其在食品防腐中的应用

随着对食品安全和健康问题的普遍关注,消费者对天然产物的兴趣越来越高。由于化学防腐剂存在的问题和缺陷,天然生物防腐剂引起了食品工业界的极大重视。采用天然防腐剂,可以赋予食品更高的营养价值,减少或完全停用化学防腐剂,并且确保食品的微生物安全性。天然生物防腐剂是指来源于植物、动物、微生物的具有预防食品腐败作用的抗菌物质。天然防腐剂的作用方式是抑制微生物的生长及发生在食品中的氧化反应和酶促反应。本文综述天然生物防腐剂的种类、抑菌机理及其在食品防腐中的应用研究现状,阐述在栅栏技术中的应用效果,展望天然生物防腐剂今后的应用前景及其在开发应用中需要研究解决的主要问题。