Isolation of a Rhodobacter sphaeroides mutant with enhanced hydrogen production capacity from transposon mutagenesis by NH4+ nitrogen resource |
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Authors: | Xueqing Wang Xiaomin Wu Jun Hu Anlong Zhang Duo Chen Honghui Yang Xingyuan Ma Liejin Guo |
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Affiliation: | 1. College of Bioresources Chemical & Materials Engineering, College of Environmental Science & Engineering, Shaanxi University of Science & Technology, Xi''an, Shaanxi, 710021, PR China;2. College of Science, National University of Defense Technology, Changsha, Hunan, 410073, PR China;3. State Key Laboratory of Multiphase Flow in Power Engineering, Xi''an Jiaotong University, Xi''an, Shaanxi, 710049, PR China |
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Abstract: | In order to mitigate the ammonia-repression effect of nitrogenase in photosynthetic bacteria, we screened a library of transposon insertion mutants that showed better hydrogen production performance under ammonia-repressed conditions, revealing a relevant regulatory gene. The transposon plasmid pRL27 was engaged for transposon mutagenesis in a cbbR nullmutant of photosynthetic bacteria that has poor growth in the presence of ammonia, and mutants with better growth characteristics were successfully isolated. The hydrogen production yield and rate of one mutant (WRR04) were improved by 14.16% and 31.38%, respectively. BLAST analysis revealed that the interrupted DNA sequence encodes trmB, a transcriptional regulator. Additionally, the mutants WTF05 (trmB-) and WTR06 (trmB-, cbbR-) were constructed, and their H2 production rates were increased remarkably by 54.72% and 41.44% comparing with the wild strain, respectively. The enhancement of nitrogenase activity demonstrates that the rupture of trmB could partly de-repress the activity of nitrogenase inhibited by ammonium for Rhodobacter sphaeroides. |
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Keywords: | Hydrogen production Transposon mutagenesis Ammonium tolerance |
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