Open AccessRoles of siderophore in manganese‐oxide reduction by S hewanella oneidensis MR ‐1
Author(s) -
Kouzuma Atsushi,
Hashimoto Kazuhito,
Watanabe Kazuya
Publication year - 2012
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2011.02444.x
Subject(s) - shewanella oneidensis , siderophore , shewanella , transposon mutagenesis , mutant , shewanella putrefaciens , transposable element , ferrous , bacteria , chemistry , complementation , biochemistry , biology , microbiology and biotechnology , gene , genetics , organic chemistry
Dissimilatory metal‐reducing bacteria ( DMRB ), such as S hewanella oneidensis MR ‐1, are of great interest for their importance in the biogeochemical cycling of metals and utility in biotechnological processes, such as bioremediation and microbial fuel cells. To identify genes necessary for metal reduction, this study constructed a random transposon‐insertion mutant library of MR ‐1 and screened it for isolating mutants that were deficient in metal reduction. Examination of approximately 5000 mutants on lactate minimal‐medium plates containing MnO 2 resulted in the isolation of one mutant, strain N 22‐7, that showed a decreased MnO 2 ‐reduction activity. Determination of a transposon‐insertion site in N 22‐7 followed by deletion and complementation experiments revealed that the disruption of SO 3030, a siderophore biosynthesis gene, was responsible for the decreased MnO 2 ‐reduction activity. In Δ SO 3030 cells, iron and cytochrome contents were decreased to approximately 50% of those in the wild‐type cells, when they were incubated under MnO 2 ‐reduction conditions. In addition, the transcription of genes encoding outer‐membrane cytochromes necessary for metal reduction was repressed in Δ SO 3030 under MnO 2 ‐reduction conditions, while their transcription was upregulated after supplementation of culture media with ferrous iron. These results suggest that siderophore is important for S . oneidensis MR ‐1 to respire MnO 2 , because iron availability influences the expression of cytochromes necessary for metal reduction.