Nanobiogeochemistry of Microbe/Mineral Interactions: A Force Microscopy and Bioinformatics Approach

摘要

Iron-reducing microorganisms, like Shewanella oneidensis, have received a great deal of attention in the literature because of their ability to couple the oxidation of organic contaminants to the reduction of Fe(III) in minerals. The mechanism by which this microorganism transfers electrons to Fe(III) in a minerals structure is unknown. We used atomic force microscopy (AFM) to measure forces at the interface between an iron oxide mineral and a living cell of S. oneidensis. A unique force-signature was attributed to outer membrane proteins synthesized for the specific purpose of forming a bond with the surface of an iron oxide. To confirm this hypothesis, we used AFM to measure forces between an iron oxide mineral and each of two outer membrane cytochromes purified from S. oneidensis. There is a strong correlation between the whole cell and pure protein force spectra suggesting that these two cytochromes play a prominent role in the terminal electron transfer to Fe(III) in minerals.