Effects of a Nitrogen-Fixing Indigenous Bacterium (Klebsiella pneumoniae) on the Growth and Development of the Halophyte Salicornia bigelovii as a New Crop for Saline Environments

Salicornia bigelovii is a novel crop for salty soils, which can contribute to arid‐zone management where irrigation with salty water, including sea water, is now a necessity. Nitrogen fixation by bacteria associated with the roots of S. bigelovii and similar halophytes is an important source of available nitrogen in salt marsh ecosystems. However, the diversity of the rhizosphere of Salicornia is unknown. Five areas around the Bay of La Paz in Baja California Sur, Mexico were sampled to detect nitrogen‐fixing bacteria associated with this halophyte; from these, 18 colonies were isolated. Only one showed high acetylene reduction activity. This bacterium was identified as Klebsiella pneumoniae. The effects of K. pneumoniae were evaluated at the germination and early seedling growth stages of two genotypes of S. bigelovii (‘wild genotype’ and cultivar SOS‐10), as an alternative crop for semiarid and saline environments. This bacterium, in conjunction with Azospirillum halopraeferens, was tested for growth‐promoting ability when inoculated on S. bigelovii genotypes under various saline concentration conditions. During germination and early seedling growth, K. pneumoniae showed high specificity for the wild S. bigelovii genotype, while A. halopraeferens was more specific for the improved S. bigelovii genotype SOS‐10. This is the first report of K. pneumoniae as a nitrogen‐fixing bacterium associated with the oilseed S. bigelovii, a novel halophyte crop. A reliable biological method, based on beneficial bacteria, is suggested to help maintain or improve the fertility of soils sustaining Salicornia fields.     

大熊猫源肺炎双球菌的分离鉴定

为了分析、丰富表现呼吸道症状的患病大熊猫的病原病因学,选用有效药物预防控制该类疾病,试验对从中国大熊猫保护中心采集的患病大熊猫鼻腔拭子进行了细菌培养、菌落形态学观察、生化试验、溶血试验和动物致病性试验。结果表明:分离到致病性肺炎双球菌;分离菌对万古霉素、青霉素、氨苄西林、红霉素、羧苄青霉素和阿莫西林等高度敏感,对丙氟哌酸、卡那霉素、四环素等中度敏感,对链霉素、强力霉素等药物有耐药性。     

Fatal suppurative meningoencephalitis caused by Klebsiella pneumoniae in two calves

One calf died (No. 1) and another was euthanized following astasia (No. 2). Histopathological examination revealed suppurative meningoencephalitis in these calves. Klebsiella pneumoniae antigens were detected in lesions. Thymocytes were decreased in the thymus cortex in both cases. 16S rRNA gene sequencing of the No. 1 isolate and bacterial extracts from formalin fixed paraffin embedded sections of No. 2 revealed that both samples were K. pneumoniae. The No. 1 isolate showed multidrug resistance against penicillin antibiotics, fosfomycin, streptomycin, macrolide antibiotics, tetracycline antibiotics, and clindamycin. Immunosuppression is a significant septicemic K. pneumoniae infection risk factor. Our study provides new aspects regarding K. pneumoniae infections in cattle, bacterial meningoencephalitis differentiation, and K. pneumoniae and bacterial meningoencephalitis treatments.     

弗兰克氏菌nifH及nifD基因的定位

利用限制性内切酶酶切和分子杂交等手段,对弗兰克氏菌菌株At4和Hr16的固氮基因克隆的nifH(pPC1201)、nifD(pPC1202)及nifK(pPC1203)基因为探针杂交,定位了At4和Hr16的nifH和nifD基因。同时发现,一条1.3kb的BamHI片段丢失。     

鸡毒支原体LAMP可视化检测方法的建立

为建立一种鸡毒支原体(MG)的快速检测方法,本研究根据GenBank中MG的基因保守序列,设计1套特异性环介导等温扩增(LAMP)引物,优化反应条件,建立了MG LAMP的可视化检测方法。该方法的敏感性可达10 fg/μL,高于常规PCR方法100倍;其特异性好,对其他的鸡常见病原体的检测结果均为阴性。MG LAMP反应只需一个可控温的水浴锅,在1 h内完成全部反应,通过肉眼观察颜色直接判定结果。本研究建立的LAMP方法具有灵敏度高、特异性好、操作简便的优点,可用于MG感染的快速检测。     

大熊猫肺炎克雷伯氏杆菌的分子诊断

建立了PCR分子诊断技术 ,并对大熊猫主要肠道病原菌肺炎克雷伯氏杆菌进行检测。结果表明 ,该方法简单、快速、敏感、结果可靠 ,适用于大熊猫肠道病原菌的早期诊断 ,该方法具有广阔的应用前景。     

Mycoplasma suipneumoniae and mycoplasma flocculare in the growth precipitation test.

A number of laboratory and field strains of Mycoplasma suipneumoniae and Mycoplasma flocculare were subjected to a comparative examination by the growth precipitation test. It was found that all the strains could readily be identified by that test. Slight evidence of cross-reaction was noted for a few of the laboratory strains, but not until late in the observation period. Only some of the field strains would form precipitates when primary cultures (from tissue suspensions) were used, but all strains could be identified already in the second and third passages. The test therefore seems well suited for distinguishing the two species from each other.     

猪肺炎霉形体及其膜致细胞病变的研究

采用培养的兔肾原代单层细胞，接种猪肺炎霉形体及其膜部分，观察其致细胞病变情况，当霉形体接种量为５～１５μｇ／ｍｌ菌体蛋白时，无细胞病变作用，而接种量为２０～３０μｇ／ｍｌ菌体蛋白时，均有致细胞病变作用；当霉形体膜接种量为５～２５μｇ／ｍｌ膜蛋白时，无细胞病变作用，接种量达３０～５０μｇ／ｍｌ膜蛋白时，均可使细胞病变。随着接种量的加大和作用时间的延长，致细胞病变的程度增强。     

Chlamydia pneumoniae enhanced the expression of ICAM-1 in cultured human umbilical vein endothelial cells

AIM: To investigated the effects of Chlamydia pneumoniae (C.pneumoniae) infection on the expression of intercellular adhesion molecule-1 (ICAM-1) in cultured human umbilical vein endothelial cells (HUVECs). METHODS: After propagated in HEP-2 cells, C. pneumoniae organisms were infected to HUVECs. The infection was assessed by ectromicroscope and PCR. The expression of ICAM-1 on HUVECs was detected by flow cytometry before infection and 12 h, 24 h, 48 h, 72 h after infection. RT-PCR was used to detect the ICAM-1 mRNA expression. RESULTS: C.pneumoniae was able to infect cultured HUVECs. After infection, the expression of ICAM-1 on the surface of cultured HUVECs was increased,, the peak was at the time of about 24-48 h; The light quantative RT-PCR analysis demonstrated that the infection also enhanced the ICAM-1 mRNA expression. CONCLUSION: The ability of C.pneumoniae to grow in HUVECs and to stimulate the expression of ICAM-1 protein and mRNA suggests that C.pneumoniae may playa role in atheriosclerosis.     

仔猪克雷伯氏菌病的病原分离鉴定及其疫苗制备

克雷伯氏杆菌既是一种人兽共患病病原又是一种可引起多种动物患病的条件性致病菌。常可引起仔猪败血性克雷伯氏杆菌病,引起仔猪大量死亡,本文对临床采集的病料进行镜检、细菌分离培养、生化特性和致病性分析后分离出克雷伯氏菌;同时制备了自家氢氧化铝灭活苗,并对疫苗的安全性、保护性及免疫性进行了检测。结果表明:利用当地发病猪群分离的克雷伯氏杆菌制备的灭活苗性能良好使用安全可靠。