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Screening and characterization of H_(2)-uptake hydrogenase (Hup~(-)) mutants of Azorhizobium caulinodans

Wang Nan, Wu Yongqiang, Hong Li, Fan Qingsheng

Nanjing Agricultural University.Nanjing 210095,Jiangsu；China

Abstract

Two Hup~(-) mutants (R-49 and R-309) from Azorhizobium caulinodans were obtained by Tn5 insertion mutation and their nitrogenase activities were significantly decreased to about 6%--8% of their wild type. Southern hybridization indicated that A. caulinodans genomic DNA contained homological DNA fragment with B. japonicum hup genes. When a plasmid (pHR11) containing 5.9kb hup genes of B. japonicum was transferred to A. caulinodans Hup~(-) mutants, the hydrogenase activities of transconjugants were able to restore to about 60% of their wild type and the nitrogenase activities also increased.

Key words: Azorhizobium caulinodans;Hydrogenase;Nitrogenase;Transposn Tn5

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Citing This Article：

Wang Nan, Wu Yongqiang, Hong Li, Fan Qingsheng. Screening and characterization of H_(2)-uptake hydrogenase (Hup~(-)) mutants of Azorhizobium caulinodans. Acta Physiol Sin 1997; 49 (4): (in Chinese with English abstract).