Pathogenic and molecular characterisations of pigeonpea wilt pathogen Fusarium udum

Thirty two pathogenic isolates of Fusarium udum from different pigeonpea growing areas in India were studied for pathogenic and molecular variability. Pathogenic variability was tested on 12 pigeonpea differential genotypes, which revealed prevalence of five variants in F. udum. The amount of genetic variation was evaluated by Polymerase Chain Reaction (PCR) amplification with 20 random amplified polymorphic DNA (RAPD) markers and nine microsatellite markers. All amplifications revealed scorable polymorphisms among the isolates, and a total of 137 polymorphic fragments were scored for the RAPD markers and 16 alleles for the simple sequence repeat (SSR) markers. RAPD primers showed 86% polymorphism. Genetic similarity was calculated using Jaccard's similarity coefficient and cluster analysis was used to generate a dendrogram showing relationships between them. Isolates could be grouped into three subpopulations based on molecular analysis. Results indicated that there is high genetic variability among a subpopulation of F. udum as identified by RAPD and SSR markers and pathogenicity on differential genotypes.     

Plant extracts abated pathogenic Fusarium species of millet seedlings

Millet is an important crop threatened by soil-borne pathogenic fungi worldwide, but the position of these soil-borne fungi most especially Fusarium has not been evaluated in south-western Nigeria alongside their biocontrol using plant extracts. This study investigates the effects (in vitro and in vivo) of Moringa oleifera, Manihot esculenta (peels) and Senna alata at 5, 10 and 15% g/ml concentrations on Fusarium anthophilum, Fusarium verticillioides, Fusarium oxysporum and Fusarium scirpi. The in vivo experimental layout was arranged in a completely randomised design and all obtained data, both in vitro and in vivo, were statistically analysed using Minitab version 15. The extract of Moringa oleifera, Manihot esculenta (peels) and S. alata at 5, 10 and 15% g/ml concentrations showed significant (p?<?0.05) antagonistic effect in vitro and in vivo on F. anthophilum, F. verticillioides and F. oxysporum. Moringa oleifera and S. alata at 5 and 10% g/ml significantly (p?<?0.05) reduced the disease incidence and disease severity of F. scirpi on millet seedlings. Thus, Moringa oleifera appears to be the most effective extract followed by Manihot esculenta, while S. alata was the least effective plant extract. Hence, the effectiveness of plant extracts on pathogenic Fusarium of millet justified their management strategy geared towards sustainable millet growth in Nigeria.     

Antimicrobial activity of some 2-amino-5-subsituted pyridine derivatives

A series of 2-amino-5-substituted pyridine derivatives were prepared and evaluated against phytopathogenic fungi and bacteria under laboratory conditions. Position 4 on the pyridine ring has notable fungicidal and bactericidal activity, greater than position 3 and/or position 6. Reaction of 1-hydroxymethyl benzotriazole with the amino group of the pyridine ring gave better fungicidal activity than substitution on the carbon of the pyridine ring (compound 4 versus 1c). Replacing the benzotriazole moiety with thiophenol exhibited the strongest fungicidal and bactericidal activity in this series (compound 3).     

江苏、安徽的禽致病性大肠杆菌

禽致病性大肠杆菌(Avian Pathogenic Escherichia coli,APEC)司引起禽类的多种疾病,是目前严重危害养禽业的传染病之一[1-2].APEC有复杂的血清型和广谱的耐药性,严重制约了该病的有效防控.最近的研究表明APEC能引起包括人在内的哺乳动物发病,提示APEC可能是人畜共患病的潜在病原体.因此,对APEC分子流行病学的研究,为进一步开展对该病的防控提供参考.     

一株促甲烷氧化假单胞菌Pseudomonas putida P7的分离及电活性特征

微生物胞外呼吸是厌氧环境中控制性能量代谢方式,直接驱动着C、N、S、Fe等关键元素的生物地球化学循环。微生物纳米导线（Microbial nanowires）的发现,被认为是微生物胞外呼吸的里程碑事件,推动了电微生物学（Electromicrobiology）的形成与发展。微生物纳米导线是一类由微生物合成的,具有导电性的纤维状表面附属结构。通过细菌纳米导线,微生物胞内代谢产生的电子可以长距离输送到胞外受体或其他微生物,改变了电子传递链仅仅局限于细胞胞内的认识,从而大大拓展了微生物-胞外环境互作的范围。微生物纳米导线的良好导电性,赋予了其作为天然纳米材料的广阔应用前景。目前,微生物纳米导线的导电机制、生态功能及其在生物材料、生物能源、生物修复及人体健康多领域的应用,已经成为新兴电微生物学的前沿与热点。然而,微生物纳米导线的生物学、生态学功能尚不清楚,它的电子传递机制仍存在分歧。本文在系统性总结微生物纳米导线性质、功能的基础上,以Geobacter sulfurreducens和Shewanella oneidensis纳米导线为模型,详细阐述了纳米导线的组成与结构、表征与测量方法、导电理论（类金属导电学说与电子跃迁学说）及其潜在的应用,最后提出了未来微生物纳米导线研究的重点方向、挑战与机遇。     

218例肛周脓肿患者脓液培养及药物敏感情况分析

通过回顾性归纳分析218例原发性成脓期肛周脓肿患者脓液标本细菌培养及药敏试验结果,了解肛周脓肿患者脓液中主要致病菌分布情况及药敏试验状况。结果表明,218例患者脓液培养共分离出病原菌247株,革兰阳性菌41株（占16.6%）,革兰阴性菌206株（占83.40%）,差异具有统计学意义（P＜0.05）。革兰阴性菌中大肠埃希菌（Escherichia coli）145株（占58.71%）,肺炎克雷伯菌（Klebsiella pneumoniae）38株（占15.38%）,差异具有统计学意义（P＜0.05）。药敏试验显示革兰阴性菌对亚胺培南、丁胺卡那、美罗培南、哌拉西林/他唑巴坦敏感率为100%,对替卡西林/克拉维酸、头孢哌酮/舒巴坦、米诺环素、氯霉素、头孢西丁、头孢吡肟、头孢他啶敏感率均达到85%以上;革兰阳性菌对万古霉素、亚胺培南、利奈唑胺敏感率为100%,对替考拉宁、链霉素、氯霉素、左氧氟沙星、头孢吡肟敏感率均达到85%以上,均为敏感抗菌药物。肛周脓肿患者致病菌分布发生了改变,革兰阴性菌占比下降,革兰阳性菌占比上升,仍以大肠埃希菌急性感染为主。临床上存在敏感抗菌药物,可以首选头霉素类抗生素头孢西丁治疗肛周脓肿,然后根据具体药敏试验结果及时调整使用敏感的抗生素。     

微生物的运动性和趋化性在共生体系中的作用

许多共生关系依赖于宿主从环境中募集微生物相互作用后形成,而共生微生物的发现和定殖宿主的机制尚不清楚。通常认为环境共生体的获得往往需要运动和趋化作用来使微生物主动迁移和定殖。这些行为在建立和维持共生相互作用方面的关键性已经在少数模式系统中得到了很好地确立和证实。但在大多数环境共生体中,这些行为在很大程度上仍被忽视了。基于对模式案例的分析,总结了宿主应用共生微生物的趋化性和运动性在何时、何地、如何实现共生募集以及有哪些影响募集的因素。强调了这些共生行为在大范围的宿主和环境中的重要性,并对共生关系中微生物的运动性和趋化性的作用研究进行了展望,旨在为今后的相关研究和实际应用提供参考。     

Genome‐wide association study identifies an NLR gene that confers partial resistance to Magnaporthe oryzae in rice

Because of the frequent breakdown of major resistance (R) genes, identification of new partial R genes against rice blast disease is an important goal of rice breeding. In this study, we used a core collection of the Rice Diversity Panel II (C‐RDP‐II), which contains 584 rice accessions and are genotyped with 700 000 single‐nucleotide polymorphism (SNP) markers. The C‐RDP‐II accessions were inoculated with three blast strains collected from different rice‐growing regions in China. Genome‐wide association study identified 27 loci associated with rice blast resistance (LABRs). Among them, 22 LABRs were not associated with any known blast R genes or QTLs. Interestingly, a nucleotide‐binding site leucine‐rich repeat (NLR) gene cluster exists in the LABR12 region on chromosome 4. One of the NLR genes is highly conserved in multiple partially resistant rice cultivars, and its expression is significantly up‐regulated at the early stages of rice blast infection. Knockout of this gene via CRISPR‐Cas9 in transgenic plants partially reduced blast resistance to four blast strains. The identification of this new non‐strain specific partial R gene, tentatively named rice blast Partial Resistance gene 1 (PiPR1), provides genetic material that will be useful for understanding the partial resistance mechanism and for breeding durably resistant cultivars against blast disease of rice.     

Purification,Characterization, and Sequencing of a Novel Type of Antimicrobial Peptides,Fa-AMP1 and Fa-AMP2, from Seeds of Buckwheat (Fagopyrum esculentum Moench.)

Novel antimicrobial peptides (AMP), designated Fa-AMP1 and Fa-AMP2, were purified from the seeds of buckwheat (Fagopyrum esculentum Moench.) by gel filtration on Sephadex G75, ion-exchange HPLC on SP COSMOGEL, and reverse-phase HPLC. They were basic peptides having isoelectric points of over 10. Fa-AMP1 and Fa-AMP2 had molecular masses of 3,879 Da and 3,906 Da on MALDI-TOF MS analysis, and their extinction coefficients in 1% aqueous solutions at 280 nm were 42.8 and 38.9, respectively. Half of all amino acid residues of Fa-AMP1 and Fa-AMP2 were cysteine and glycine, and they had continuous sequences of cysteine and glycine. The concentrations of peptides required for 50% inhibition (IC₅₀) of the growth of plant pathogenic fungi, and Gram-positive and -negative bacteria were 11 to 36 μg/ml. The structural and antimicrobial characteristics of Fa-AMPs indicated that they are a novel type of antimicrobial peptides belonging to a plant defensin family.     

Prevention of Pathogenic Escherichia coli Infection in Mice and Stimulation of Macrophage Activation in Rats by an Oral Administration of Probiotic Lactobacillus casei I-5

Lactobacillus casei I-5 isolated from an alcohol fermentation broth enhanced immunity and prevented pathogenic infection as a probiotic. Mice fed with I-5 cells for 11 days prior to an intraperitoneal challenge with pathogenic Escherichia coli Juhl exhibited a high survival rate compared with the control group. Rats fed with I-5 cells for 10 days significantly increased the phagocytosis of peritoneal macrophages. In a cell culture system employing peritoneal macrophages from rats, the I-5 administration activated NF-κB stimulated by LPS. It also enhanced LPS-stimulated IL-12 and TNF-α production, but not IL-6 production. These results show that L. casei I-5 effectively prevented infection by pathogenic E. coli possibly through the activation of peritoneal macrophages. The strain would be useful to prevent pathogenic microbial infections in humans and farm animals.