Open AccessElectron transfer from Shewanella algae BrY to hydrous ferric oxide is mediated by cell‐associated melanin
Author(s) -
Turick Charles E,
Caccavo F,
Tisa Louis S
Publication year - 2003
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/s0378-1097(03)00096-x
Subject(s) - melanin , ferric , algae , chemistry , shewanella , extracellular , biophysics , biochemistry , botany , biology , inorganic chemistry , bacteria , genetics
Shewanella algae BrY uses insoluble mineral oxides as terminal electron acceptors, but the mechanism of electron transfer from cell surface to mineral surface is not well understood. We tested the hypothesis that cell‐associated melanin produced by S. algae BrY serves as an electron conduit for bacterial–mineral reduction. Results from Fourier transform infrared spectroscopy and cell surface hydrophobicity assays indicated that extracellular melanin was associated with the cell surface. With H 2 as electron donor, washed cell suspensions of melanin‐coated S. algae BrY reduced hydrous ferric oxide (HFO) 10 times faster than cells without melanin. The addition of melanin (20 μg ml −1 ) to these melanin‐free cells increased their HFO reduction rate two‐fold. These results suggest that cell‐associated melanin acts as an electron conduit for iron mineral reduction by S. algae BrY.