A simple and efficient method for cloning the flanking genomic sequences of a known DNA region is reported in this study. This method combined partial restriction endonuclease digestion, adaptor ligation, and a single...A simple and efficient method for cloning the flanking genomic sequences of a known DNA region is reported in this study. This method combined partial restriction endonuclease digestion, adaptor ligation, and a single round polymerase chain reaction. Total genomic DNA was partially digested with the frequent-cutting restriction enzyme Mse I. The partially digested products were ligated to an unphosphorylated adaptor. A hot start PCR amplification with Taq polymerase and dNTP was performed with a DNA-specific primer and the adaptor primer complementary to the adaptor and the Mse I recognition site. The amplified products were fractionated, cloned and sequenced. By this method, we cloned the downstream region of a gynoecious marker TG/CAC234 from cucumber （Cucumis sativus L.）.展开更多
为实现高氨氮废水的高效低耗稳定去除,在常温条件下,对曝气生物滤池(BAF)中实现与稳定短程硝化-厌氧氨氧化自养脱氮工艺进行了研究。研究结果表明:常温条件下,BAF接种二沉池回流污泥,采用闷曝-连续运行结合的接种挂膜方式,可成功实现短...为实现高氨氮废水的高效低耗稳定去除,在常温条件下,对曝气生物滤池(BAF)中实现与稳定短程硝化-厌氧氨氧化自养脱氮工艺进行了研究。研究结果表明:常温条件下,BAF接种二沉池回流污泥,采用闷曝-连续运行结合的接种挂膜方式,可成功实现短程硝化-厌氧氨氧化一体化自养脱氮。闷曝阶段使种泥活性恢复,而连续流运行过程中游离氨(FA)浓度高,可抑制亚硝酸盐氧化菌(NOB),实现BAF中亚硝酸盐累积;通过调整BAF回流方式,降低回流液中NO_2^-N-,防止NOB生长,并通过厌氧氨氧化(Anammox)滤池出水回流方式,接种微量Anammox菌,运行80 d可实现短程硝化-厌氧氨氧化,140 d后系统运行稳定,总氮(TN)去除率达76.62%。生物滤池有利于短程硝化-厌氧氨氧化工艺的实现与稳定,生物膜中不同厚度存在好氧缺氧环境,利于氨氧化菌(AOB)和Anammox菌共存;滤料的过滤作用有效地防止了Anammox菌流失,使其在系统中不断累积生长。不仅如此,AOB和Anammox菌均为自养菌且生长缓慢,避免了生物滤池的频繁反冲洗,简化了生物滤池的运行。气水比是BAF中一体化运行的关键参数,本研究中最佳的气水比为12:1,氨氮去除负荷达到0.91 kg N·m^(-3)·d^(-1),氨氮和TN去除率分别可达96.86%和85.47%。展开更多
基金partially supported by the Program 30470120,30671419,30700541 from the National Natural Science Foundation of Chinaby the 863 Programs 2006AA10Z108,2006AA100108 from the Ministry of Science and Technology of China+2 种基金by the Ph.D Funding 20050307009 from the Ministry of Education of Chinaby the Program BK2006139 from the Natural Science Foundation of Jiangsu Provinceby Research Fund KJ05006 from Nanjing Agricultural University,China.
文摘A simple and efficient method for cloning the flanking genomic sequences of a known DNA region is reported in this study. This method combined partial restriction endonuclease digestion, adaptor ligation, and a single round polymerase chain reaction. Total genomic DNA was partially digested with the frequent-cutting restriction enzyme Mse I. The partially digested products were ligated to an unphosphorylated adaptor. A hot start PCR amplification with Taq polymerase and dNTP was performed with a DNA-specific primer and the adaptor primer complementary to the adaptor and the Mse I recognition site. The amplified products were fractionated, cloned and sequenced. By this method, we cloned the downstream region of a gynoecious marker TG/CAC234 from cucumber （Cucumis sativus L.）.
文摘为实现高氨氮废水的高效低耗稳定去除,在常温条件下,对曝气生物滤池(BAF)中实现与稳定短程硝化-厌氧氨氧化自养脱氮工艺进行了研究。研究结果表明:常温条件下,BAF接种二沉池回流污泥,采用闷曝-连续运行结合的接种挂膜方式,可成功实现短程硝化-厌氧氨氧化一体化自养脱氮。闷曝阶段使种泥活性恢复,而连续流运行过程中游离氨(FA)浓度高,可抑制亚硝酸盐氧化菌(NOB),实现BAF中亚硝酸盐累积;通过调整BAF回流方式,降低回流液中NO_2^-N-,防止NOB生长,并通过厌氧氨氧化(Anammox)滤池出水回流方式,接种微量Anammox菌,运行80 d可实现短程硝化-厌氧氨氧化,140 d后系统运行稳定,总氮(TN)去除率达76.62%。生物滤池有利于短程硝化-厌氧氨氧化工艺的实现与稳定,生物膜中不同厚度存在好氧缺氧环境,利于氨氧化菌(AOB)和Anammox菌共存;滤料的过滤作用有效地防止了Anammox菌流失,使其在系统中不断累积生长。不仅如此,AOB和Anammox菌均为自养菌且生长缓慢,避免了生物滤池的频繁反冲洗,简化了生物滤池的运行。气水比是BAF中一体化运行的关键参数,本研究中最佳的气水比为12:1,氨氮去除负荷达到0.91 kg N·m^(-3)·d^(-1),氨氮和TN去除率分别可达96.86%和85.47%。
文摘以普通活性污泥为接种污泥,采用人工配制无机氨氮废水进行单级自养脱氮工艺快速启动研究。启动过程经历了污泥适应期、部分短程硝化选择期以及单级自养脱氮实现期3个阶段。经过29 d的培养驯化,通过控制游离氨的方法实现了部分短程硝化。当出水中亚硝酸盐积累率达到60%左右时,立即将序批式生物膜反应器(SBBR)由连续曝气改为间歇曝气,间歇曝气使得厌氧氨氧化菌(AAOB)的富集与亚硝酸氧化菌(NOB)的淘汰同时进行,并且避免了高浓度亚硝酸盐对AAOB的抑制作用,从而实现了单级自养脱氮的快速启动。实验仅用50 d成功启动了SBBR单级自养脱氮工艺,总氮容积去除负荷达到0.173 kg N/(m3·d),氨氮的平均去除率达到98.68%,总氮的平均去除率达到80.87%。成功启动之后,反应器内只有少量的悬浮污泥,大部分的污泥都附着在填料上,污泥颜色呈褐色,而反应器内壁及出水管上附着的污泥呈浅砖红色,表明反应器内富集了大量的AAOB。
