Defining How a Microbial Cell Senses and Responds to a Redox Active Environment

This grant was for four years, and the work was designed to look at the mechanisms of extracellular electron transfer by the dissimilatory iron reducing bacteria Shewanella oneidensis MR-1, and other closely related Shewanella strains and species. During this work, we defined many of the basic physiological and biochemical properties of the Shewanella group, Much of which was summarized in review articles. We also finished and published the genome sequence of strain MR-1, the first of the shewanellae to have its genome sequenced. Control at the transcriptional and translational level was studied in collaboration with colleagues at PNNL and ANL. We utilized synchrotron X-ray radiation to image both the bacteria and the metal oxide particles via a technique called STXM, synchrotron X-ray absorption (ref. No.9), and X-ray microbeam analysis. We purified several of the cytochromes involved with metal reduction, and improved gene annotation of the MR-1 genome. The conductive appendages (nanowires) of MR-1 were described and characterized. Comparative genomics and biochemistry revealed that the pathway for the utilization of N-acetyl glucosamine in the various strains of Shewanella exhibited great variability, and had a number of previously unknown genes