Direct and Indirect Mechanisms of Microbial Iron Reduction

摘要

We found that the direct and indirect pathways for Fe reduction by Shewanella oneidensis have significant overlap. We showed that outer membrane proteins that were previously thought to contact Fe 'directly' also play a key role in reducing electron shuttling molecules like AQDS. Thus, a challenge for future research will be to demonstrate how electron transfer between these proteins and minerals works in detail. In addition, we defined the region of the Arc control system in S. oneidensis, and showed that it positively regulates the expression of a cluster of genes encoding a DMSO reductase. This reductase fs similar to that used for Fe respiration with respect to its localization to the external face of the outer membrane. This underscores the metabolic versatility of Shewanella, and suggests that in addition to minerals, Shewanella may perceive DMS0 as an 'insoluble' substrate. This opens up an exciting new area for future research: how do microbes affect the DMSO cycle in the marine environment. Several publications resulted from this award, including journal articles in Applied and Environmental Microbiology, Molecular Microbiology, Corrosion Science, and PNAS (hopefully--the manuscript is in review.). A book chapter on 'What genetics offers geobiology' was also written. 2 - students. 2 postdocs.- and 2 undergrads were supported in part by this award.