Generation of Bradyrhizobium japonicum mutants with increased N2O reductase activity by selection after introduction of a mutated dnaQ gene.

ABSTRACT: We obtained two beneficial mutants of Bradyrhizobium japonicum USDA110 with increased nitrous oxide (N(2)O) reductase (N(2)OR) activity by introducing a plasmid containing a mutated B. japonicum dnaQ gene (pKQ2) and performing enrichment culture under selection pressure for N(2)O respiration. Mutation of dnaQ, which encodes the epsilon subunit of DNA polymerase III, gives a strong mutator phenotype in Escherichia coli. pKQ2 introduction into B. japonicum USDA110 increased the frequency of occurrence of colonies spontaneously resistant to kanamycin. A series of repeated cultivations of USDA110 with and without pKQ2 was conducted in anaerobic conditions under 5% (vol/vol) or 20% (vol/vol) N(2)O atmosphere. At the 10th cultivation cycle, cell populations of USDA110(pKQ2) showed higher N(2)OR

SUBMITTER: Itakura M 

PROVIDER: S-EPMC2592905 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature