Transcriptome of dissimilatory iodate-reducing microorganisms

According to thermodynamic theory, microbial iodate reduction precedes nitrate reduction, leading to the proposal that dissimilatory iodate-reducing microorganisms (DIRMs) inhabit a unique niche between the zones of oxygen and nitrate reduction. However, our findings in iodine-rich groundwater challenge the proposed distribution pattern for DIRMs. To date, all isolated DIRMs generally have key genes of nitrate reduction and iodate reduction. In this project, we investigated the sequential reduction of nitrate and iodate by two representative DIRMs (the terrestrial isolate Azonexus hydrophilus NCP973 and the marine isolate Denitromonas iodatirespirans IR-12) under physiological conditions. Transcriptome was used to reveal the expression of key genes associated with nitrate and iodate reduction in cultures in the presences of 10 mM acetate as the electron donor) and 1 mM nitrate and 1 mM iodate as electron acceptors.