The coding product of alginate-c5-mannuronan-epimerase gene （algG gene） can catalyze the conversion of mannuronate to guluronate and determine the M/G ratio of alginate. Most of the current knowledge about genes inv...The coding product of alginate-c5-mannuronan-epimerase gene （algG gene） can catalyze the conversion of mannuronate to guluronate and determine the M/G ratio of alginate. Most of the current knowledge about genes involved in the alginate biosynthesis comes from bacterial systems. In this article, based on some algal and bacterial algG genes registered on GenBank and EMBL databases, we predicted 94 algG genes open reading frame （ORF） sequences of brown algae from the 1 000 Plant Transcriptome Sequencing Project （OneKP）. By method of transcriptomic sequence analysis, gene structure and gene localization analysis, multiple sequence alignment and phylogenetic tree construction, we studied the algal algG gene family characteristics, the structure modeling and conserved motifs of AlgG protein, the origin of alginate biosyn-thesis and the variation incidents that might have happened during evolution in algae. Although there are different members in the algal algG gene family, almost all of them harbor the conserved epimerase region. Based on the phylogenetic analysis of algG genes, we proposed that brown algae acquired the alginate bio-synthesis pathway from an ancient bacterium by horizontal gene transfer （HGT）. Afterwards, followed by duplications, chromosome disorder, mutation or recombination during evolution, brown algal algG genes were divided into different types.展开更多
分别使用硅铝比38、50、120、200、300的ZSM-5分子筛原粉制备5种催化剂为ZSM-5-38、ZSM-5-50、ZSM-5-120、ZSM-5-200、ZSM-5-300,用于催化甲醇耦合C5-C6正构烷烃芳构化反应,并对催化剂进行XRD和NH3-TPD的表征。利用100 m L固定床试验装...分别使用硅铝比38、50、120、200、300的ZSM-5分子筛原粉制备5种催化剂为ZSM-5-38、ZSM-5-50、ZSM-5-120、ZSM-5-200、ZSM-5-300,用于催化甲醇耦合C5-C6正构烷烃芳构化反应,并对催化剂进行XRD和NH3-TPD的表征。利用100 m L固定床试验装置,评价其催化甲醇耦合C5、C6反应的影响。试验结果表明:硅铝比在50左右的ZSM-5分子筛催化剂有适宜的酸密度和酸强度,其催化甲醇耦合C6烷烃反应,甲醇的转化率100%,C6烷烃的转化率达到94.3%,液相产物芳烃的选择性高。展开更多
基金The National High Technology Research and Development Program of China under contract No.2012AA10A406the National Nat-ural Science Foundation of China under contract Nos 41206116,31140070 and 31271397+3 种基金Technology Project of Ocean and Fisheries of Guangdong Province under contract No.A201201E03the Fundamental Research Funds for the Central Universities under contract No.201262003China Post-doctoral Science Foundation under contract No.2011M501167the algal transcriptome sequencing was supported by 1KP Project(www.onekp.com)
文摘The coding product of alginate-c5-mannuronan-epimerase gene （algG gene） can catalyze the conversion of mannuronate to guluronate and determine the M/G ratio of alginate. Most of the current knowledge about genes involved in the alginate biosynthesis comes from bacterial systems. In this article, based on some algal and bacterial algG genes registered on GenBank and EMBL databases, we predicted 94 algG genes open reading frame （ORF） sequences of brown algae from the 1 000 Plant Transcriptome Sequencing Project （OneKP）. By method of transcriptomic sequence analysis, gene structure and gene localization analysis, multiple sequence alignment and phylogenetic tree construction, we studied the algal algG gene family characteristics, the structure modeling and conserved motifs of AlgG protein, the origin of alginate biosyn-thesis and the variation incidents that might have happened during evolution in algae. Although there are different members in the algal algG gene family, almost all of them harbor the conserved epimerase region. Based on the phylogenetic analysis of algG genes, we proposed that brown algae acquired the alginate bio-synthesis pathway from an ancient bacterium by horizontal gene transfer （HGT）. Afterwards, followed by duplications, chromosome disorder, mutation or recombination during evolution, brown algal algG genes were divided into different types.
文摘分别使用硅铝比38、50、120、200、300的ZSM-5分子筛原粉制备5种催化剂为ZSM-5-38、ZSM-5-50、ZSM-5-120、ZSM-5-200、ZSM-5-300,用于催化甲醇耦合C5-C6正构烷烃芳构化反应,并对催化剂进行XRD和NH3-TPD的表征。利用100 m L固定床试验装置,评价其催化甲醇耦合C5、C6反应的影响。试验结果表明:硅铝比在50左右的ZSM-5分子筛催化剂有适宜的酸密度和酸强度,其催化甲醇耦合C6烷烃反应,甲醇的转化率100%,C6烷烃的转化率达到94.3%,液相产物芳烃的选择性高。
