Characterization of respiratory capabilities of Shewanella Oneidensis MR-1 Fe (III) reduction deficient mutants

Shewanella oneidensis MR-1 is a free-living gram-negative gamma-proteobacterium with high respiratory versatility which able to respire on a wide range of electron acceptors including insoluble metal oxides. The molecular mechanism on how S.oneidensis MR-1 reduces insoluble metal oxides is still not fully understood and currently under intensive studies. To further elucidate the molecular mechanism on how S.oneidensis MR-1 reduces metal oxides, we recently conducted mutagenesis on S.oneidensis MR-1 wild type strain to generate iron reduction deficient mutants. From the mutagenesis, we successfully isolated two iron reduction-deficient mutants. In this study, the respiratory capabilities of the mutants were further investigated. The mutants were tested for their ability to respire on both soluble and insoluble iron as the terminal electron acceptors. The result of anaerobic growth tests demonstrated that these two strains have remarkable lower Fe (III) reduction capabilities compared to wild-type. Determination of the mutants' respiratory phenotypes and future genetic analyses of the mutated genes in the mutants will provide more insight for a better understanding of the molecular mechanism of MR-1 iron-reduction.