为了解生鲜乳中金黄色葡萄球菌的特性,试验通过无菌采集新疆某规模化牛场混合新鲜乳样,采用常规分离方法结合PCR方法检测特异性nuc基因分离鉴定金黄色葡萄球菌,分析分离菌株对7类11种抗生素的耐药表型,采用PCR方法对金黄色葡萄球菌常见...为了解生鲜乳中金黄色葡萄球菌的特性,试验通过无菌采集新疆某规模化牛场混合新鲜乳样,采用常规分离方法结合PCR方法检测特异性nuc基因分离鉴定金黄色葡萄球菌,分析分离菌株对7类11种抗生素的耐药表型,采用PCR方法对金黄色葡萄球菌常见重要的8种毒力基因和6种耐药基因进行检测并分析其致病性。结果表明新鲜乳样中分离到一株金黄色葡萄球菌;该菌对青霉素、氨苄西林耐药,对卡那霉素、四环素4种抗生素处于中介,对庆大霉素、红霉素、头孢唑林等5种抗生素敏感;携带sec、sea、hla、tsst-1、pvl、clf A 6种毒力基因和qac A、msr A、erm C、mec A 4种耐药基因;能引起感染小鼠明显的组织病理变化并导致死亡。说明分离于生鲜乳中的金黄色葡萄球菌携带众多毒力基因和耐药基因,具有广泛的多重耐药性。展开更多
Polyketides are one of the largest groups of natural products produced by bacteria, fungi, and plants. Many of these metabolites have highly complex chemical structures and very important biological activities, includ...Polyketides are one of the largest groups of natural products produced by bacteria, fungi, and plants. Many of these metabolites have highly complex chemical structures and very important biological activities, including antibiotic, anticancer, immunosuppressant, and anti-cholesterol activities. In the past two decades, extensive investigations have been carried out to understand the molecular mechanisms for polyketide biosynthesis. These efforts have led to the development of various rational approaches toward engineered biosynthesis of new polyketides. More recently, the research efforts have shifted to the elucidation of the three-dimentional structure of the complex enzyme machineries for polyketide biosynthesis and to the exploitation of new sources for polyketide production, such as filamentous fungi and marine microorganisms. This review summarizes our general understanding of the biosynthetic mechanisms and the progress in engineered biosynthesis of polyketides.展开更多
文摘为了解生鲜乳中金黄色葡萄球菌的特性,试验通过无菌采集新疆某规模化牛场混合新鲜乳样,采用常规分离方法结合PCR方法检测特异性nuc基因分离鉴定金黄色葡萄球菌,分析分离菌株对7类11种抗生素的耐药表型,采用PCR方法对金黄色葡萄球菌常见重要的8种毒力基因和6种耐药基因进行检测并分析其致病性。结果表明新鲜乳样中分离到一株金黄色葡萄球菌;该菌对青霉素、氨苄西林耐药,对卡那霉素、四环素4种抗生素处于中介,对庆大霉素、红霉素、头孢唑林等5种抗生素敏感;携带sec、sea、hla、tsst-1、pvl、clf A 6种毒力基因和qac A、msr A、erm C、mec A 4种耐药基因;能引起感染小鼠明显的组织病理变化并导致死亡。说明分离于生鲜乳中的金黄色葡萄球菌携带众多毒力基因和耐药基因,具有广泛的多重耐药性。
文摘前茬地膜玉米免耕种植后茬小麦水氮高效利用生产技术是绿洲灌区作物高效生产的新型农田管理技术。为构建该区地膜减量和水氮高效生产技术, 2015—2017年通过3年田间试验,研究两种耕作方式、2种灌水水平和3个施氮量组合对小麦干物质积累和产量及产量构成的协同效应,其中耕作方式为覆膜玉米茬免耕直播(NT)和玉米茬传统耕作(CT),灌水量为传统灌水(I2)和传统灌水减量20%(I1),施氮量为纯N 225 kg hm–2(N3)、180kghm–2(N2)和135kghm–2(N1)。结果表明,耕作方式、灌水水平、施氮量对小麦群体生长速率、干物质积累量均有显著影响。与CT相比,NT显著增大全生育期生长速率,提高22.0%～28.0%,NT促进小麦地上干物质积累,提高6.4%～7.4%,收获期生物产量提高5.4%～15.1%。免耕低灌(NTI1)较传统耕作高灌(CTI2)的生长速率增大7.7%～13.4%,干物质积累量提高3.1%～5.9%,收获期生物产量提高8.7%～10.5%。免耕低灌中施氮(NTI1N2)较传统耕作高灌中、高施氮(CTI2N2、CTI2N3)生长速率分别增大6.9%～20.5%与4.1%～14.0%,收获期生物产量分别提高7.8%～9.7%与4.8%～10.2%。NT比CT增产10.1%～10.4%,NTI1较CTI2、CTI1分别增产13.0%～14.8%与9.4%～10.1%,NTI1N2比CTI2N2、CTI2N3分别增产3.7%～9.8%与15.2%～22.0%。从产量构成因素分析,NTI1N2提高了单位面积成穗数、穗粒数和千粒重,NTI1N2处理组合更有利于穗数、千粒重的增加。通径分析进一步证明,NTI1N2增产的主要原因是增加了单位面积穗数和千粒重。因此,在施氮量为180kghm–2的基础上,玉米茬地膜再利用免耕技术组装减少20%灌溉量(1920m3hm-2)轮作小麦模式是河西灌区小麦高效生产的可行措施。
基金Supported in part byNSF (MCB-0614916)Nebraska Research Initiatives (NRI), Redox Biology Center (RCB) Pilot Grant, andNSFC Oversea Young Scholar Award (No. 30428023)+1 种基金The research was performed in facilities renovated with support from NIH (RR015468-01)JORGENSON Joel, MARESCHAndrew, and VOGELER Chad are supported by the UCARE program at University of Nebraska-Lincoln
文摘Polyketides are one of the largest groups of natural products produced by bacteria, fungi, and plants. Many of these metabolites have highly complex chemical structures and very important biological activities, including antibiotic, anticancer, immunosuppressant, and anti-cholesterol activities. In the past two decades, extensive investigations have been carried out to understand the molecular mechanisms for polyketide biosynthesis. These efforts have led to the development of various rational approaches toward engineered biosynthesis of new polyketides. More recently, the research efforts have shifted to the elucidation of the three-dimentional structure of the complex enzyme machineries for polyketide biosynthesis and to the exploitation of new sources for polyketide production, such as filamentous fungi and marine microorganisms. This review summarizes our general understanding of the biosynthetic mechanisms and the progress in engineered biosynthesis of polyketides.
