抗菌肽与革兰氏阳性菌的互作及其机制

抗菌肽(AMP)因其具有理化性质稳定、抗菌谱广、耐高温以及不易使靶菌株产生耐药性等特点,作为一种新型的抗菌剂被提出,有望成为饲料抗生素的理想替代品,具有广阔的应用前景。但是随着对AMP的深入研究,发现部分细菌能对AMP产生耐药性。目前,还没有对AMP对革兰氏阳性(G~+)菌芽孢的抗性机制进行深入的研究。AMP对G~+菌的抑菌机制还知之甚少。在本文中,我们对AMP对G~+菌的作用靶点、抑菌机制以及G~+菌对AMP产生的耐药性等方面进行了综述。     

A novel M2e-multiple antigenic peptide providing heterologous protection in mice

Swine influenza viruses (SwIVs) cause considerable morbidity and mortality in domestic pigs, resulting in a significant economic burden. Moreover, pigs have been considered to be a possible mixing vessel in which novel strains loom. Here, we developed and evaluated a novel M2e-multiple antigenic peptide (M2e-MAP) as a supplemental antigen for inactivated H3N2 vaccine to provide cross-protection against two main subtypes of SwIVs, H1N1 and H3N2. The novel tetra-branched MAP was constructed by fusing four copies of M2e to one copy of foreign T helper cell epitopes. A high-yield reassortant H3N2 virus was generated by plasmid based reverse genetics. The efficacy of the novel H3N2 inactivated vaccines with or without M2e-MAP supplementation was evaluated in a mouse model. M2e-MAP conjugated vaccine induced strong antibody responses in mice. Complete protection against the heterologous swine H1N1 virus was observed in mice vaccinated with M2e-MAP combined vaccine. Moreover, this novel peptide confers protection against lethal challenge of A/Puerto Rico/8/34 (H1N1). Taken together, our results suggest the combined immunization of reassortant inactivated H3N2 vaccine and the novel M2e-MAP provided cross-protection against swine and human viruses and may serve as a promising approach for influenza vaccine development.     

制革下脚料酶解物叶面肥对黄瓜生长的影响

通过对黄瓜喷施由制革下脚料酶解物为原料研发的胶原肽叶面肥,调查黄瓜苗期性状、黄瓜产量和抗病性,研究胶原肽叶面肥肥效。结果表明:苗期施用50倍胶原肽叶面肥液和果期施用100倍胶原肽液叶面肥为最佳施用方法。与常用叶面肥比较,施用胶原肽叶面肥液不但可以促进黄瓜壮苗,而且还可以增加黄瓜前期产量和总产量。     

叶下珠3种提取物的抗菌和抗氧化活性

采用甲醇冷浸提取法提取叶下珠次生代谢产物,并依次采用石油醚、乙酸乙酯和正丁醇萃取,得到不同极性的提取物,通过TLC–MTT–生物自显影法、菌丝生长速率法和DPPH法测定叶下珠不同提取物的抗细菌、抗真菌和抗氧化活性,采用高效液相色谱(HPLC)分析叶下珠不同提取物中次生代谢产物的分布情况。结果表明：叶下珠乙酸乙酯和正丁醇层提取物均具有较好的抗细菌活性,对木麻黄青枯病菌的抑制活性强于阳性对照硫酸链霉素;叶下珠乙酸乙酯层提取物的抗真菌和抗氧化活性较强,其EC50和IC50分别为(1.02±0.15) mg/mL、(20.14±0.58) ?g/mL;高效液相色谱分析发现,叶下珠乙酸乙酯层提取物中的化合物主要集中在保留时间9~12 min内。叶下珠乙酸乙酯层提取物具有较强的抗细菌、抗真菌和抗氧化活性,可进一步作为活性成分分离和鉴定的候选资源。     

冷鲜牛肉微生物菌相变化及抑菌剂保鲜效果初探

针对冷鲜牛肉表面微生物菌相变化进行试验分析,选用柠檬酸、双乙酸钠和异VC钠作为保鲜剂对牛肉表面微生物进行抑制。结果表明,屠宰、预冷、分割后的无包装鲜牛肉表面菌系在低温贮藏过程中G-小杆菌菌系是导致其腐败变质的主要菌系;而真空包装鲜牛肉在贮藏期间G+球菌菌系是致使其腐败变质的主要菌系。3种保鲜剂进行冷鲜肉保鲜试验,其有效保鲜质量分数分别为柠檬酸0.6%,双乙酸钠0.6%,异VC钠0.4%。     

芽孢杆菌非核糖体肽的研究进展

芽孢杆菌产生的非核糖体肽主要有脂肽、多肽、线状聚酰胺物等类型,其生物合成是通过“硫模板多聚酶机制(th iotemp late mu ltienzym e m echan ism)”的多功能酶复合系统进行的,并经甲基化、酰基化、糖基化、杂环化和环化等进一步修饰而成。特殊的生物合成机制决定了非核糖体肽具有氨基酸组成及分子形式复杂、分子量较小、理化性质稳定、生物活性多样等特点,同时表现出了对病原微生物不同的抑、杀菌机制。非核糖体肽作为人类丰富的新型抗菌药物资源,在植物病害的生物防治、人类和动物疾病的治疗等方面显示了诱人的前景。研究芽孢杆菌及其产生的非核糖体肽在蚕业上的应用,有利于绿色、生态蚕业的发展。     

In vitro antimicrobial susceptibilities of three Porphyromonas spp and in vivo responses in the oral cavity of cats to selected antimicrobial agents

OBJECTIVES: To determine in vitro susceptibility of Porphyromonas gingivalis, P salivosa and P circumdentaria to seven antimicrobial agents by agar dilution and Epsilometer test methods and to assess the effectiveness of these antimicrobial agents in reducing the numbers of each Porphyromonas spp in the oral cavity of 16 domestic cats. DESIGN: A two-part prospective study involving in vitro antimicro-bial studies using Porphyromonas spp obtained from naturally occurring feline infections and in vivo antimicrobial response studies using client-owned cats with naturally occurring periodontal disease. PROCEDURE: Isolates (n = 25) of three feline Porphyromonas spp from the oral cavity and oral-associated disease were tested for their in vitro susceptibility to amoxycillin, amoxycillin-clavulanate, benzylpenicillin, clindamycin, doxycycline, erythromycin and metronidazole, using agar dilution and Epsilometer test methods. Digoxigenin-labelled whole chromosomal DNA probes directed against P gingivalis VPB 3492, P circumdentaria NCTC 12469T and P salivosa VPB 3313 were used to quantify organisms taken from two sample sites at the gingival margins of these cats prior to, and 5 days after, treatment with one of four commonly used antimicrobial products (amoxycillin-clavulanate, clindamycin, doxycycline or spiramycin-metronidazole). The response to treatment was assessed clinically for each cat. RESULTS: All isolates were susceptible in vitro to all seven antimicrobial agents using both methods. The numbers of P gingivalis were not reduced at the gingival sample sites by administration of amoxycillin-clavulanate for 5 days, although this treatment reduced the numbers of P salivosa and P circumdentaria to below detection levels in six of eight and two of three of sample sites, respectively; clinical improvement was not observed in cats treated with amoxycillin-clavulanate. Treatment with clindamycin, doxycycline or spiramycin-metronidazole resulted in clinical improvement and a marked reduction of all Porphyromonas isolates at the sample sites. CONCLUSION: The Epsilometer test is a simple and accurate method for determining the minimum inhibitory concentration for P gingivalis, P salivosa and P circumdentaria. All strains were susceptible in vitro to all the antimicrobial agents tested although clinical improvement of gingival disease was not noted with amoxycillin-clavulanate when given for 5 days at usual doses. This appears to be the first report of the disparity between the in vivo and in vitro susceptibility of oral bacterial strains to amoxycillin-clavulanate in the veterinary dental literature. This also appears to be the first report in which clinical and microbiological responses to commonly used antimicrobial agents for periodontal disease in cats has been documented and quantified. It was shown that treatment with clindamycin, spiramycin-metronidazole or doxycycline not only produced a substantial reduction in the number of Porphyromonas spp (in the majority of cases to below detection levels), but also resulted in substantial clinical improvement. This would indicate that these antimicrobial agents are useful adjunctive therapy to mechanical debridement in domestic cats.     

蚯蚓抗菌肽的研究进展

抗菌肽是一类广泛存在于自然界生物体中的小肽类物质,是机体先天性免疫系统的重要组成部分。由于其具有分子质量小和抗菌谱广等特点以及不同于抗生素的全新的抗菌机制,在药物开发领域和畜禽饲料添加剂等领域具有广阔的应用前景。蚯蚓抗菌肽种类多,具有良好的抑菌效果。对蚯蚓抗菌肽的分类、功能及其在生产中的应用研究进展进行了综述。     

碱性蛋白酶水解大豆多肽及抑制ACE效果的研究

[目的]为了进行碱性蛋白酶水解大豆多肽及抑制ACE效果的研究。[方法]利用胰蛋白酶、中性蛋白酶、木瓜蛋白酶、胃蛋白酶和碱性蛋白酶分别水解大豆蛋白,制备具有ACE抑制活性的大豆多肽,通过正交优化试验确定碱性蛋白酶的最佳水解条件,考察底物浓度、反应时间、反应温度与大豆蛋白酶解多肽对ACE抑制活性的影响,并将超滤法和聚丙烯酰胺凝胺电泳技术相结合,考察大豆蛋白酶水解物的分子量分布。[结果]结果表明,碱性蛋白酶的最佳水解条件为底物浓度5%,加酶量4%,水解时间2h。[结论]该研究为更好地利用大豆蛋白展示了良好的应用前景。     

乳清蛋白抗菌肽的分离纯化及活性

以乳清蛋白为原料,酶解制备具有抗菌能力的生物活性肽。采用超滤、葡聚糖凝胶层析色谱、反相高效液相色谱法对酶解液进行分离纯化,并对分离产物的氨基酸组成进行分析。结果表明:葡聚糖凝胶色谱纯化最佳流速2 mL/min,最佳样品质量浓度15 mg/mL;再由反相高效液相色谱分离的高活性抗菌肽,抑菌圈直径达到31.33 mm。氨基酸分析结果显示,高活性抗菌肽碱性氨基酸和疏水性氨基酸含量最多,分别为42.69%和37.39%。