Alkaline iron(III) reduction by a novel alkaliphilic, halotolerant, Bacillus sp. isolated from salt flat sediments of Soap Lake

Authors

Jarrod Pollock, University of California, BerkeleyFollow
Karrie A. Weber, University of Nebraska-LincolnFollow
Joe Lack, Southern Illinois University Carbondale
Laurie A. Achenbach, Southern Illinois University CarbondaleFollow
Melanie R. Mormile, University of Missouri, Rolla
John D. Coates, University of California, BerkeleyFollow

Document Type

Article

Date of this Version

2007

Citation

Applied Microbiology and Biotechnology 77:4 (2007), pp. 927-934; doi: 10.1007/s00253-007-1220-5

Comments

Copyright © 2007 Springer-Verlag. Used by permission.

Abstract

A halotolerant, alkaliphilic dissimilatory Fe(III)-reducing bacterium, strain SFB, was isolated from salt flat sediments collected from Soap Lake, WA. 16S ribosomal ribonucleic acid gene sequence analysis identified strain SFB as a novel Bacillus sp. most similar to Bacillus agaradhaerens (96.7% similarity). Strain SFB, a fermentative, facultative anaerobe, fermented various hexoses including glucose and fructose. The fructose fermentation products were lactate, acetate, and formate. Under fructose-fermenting conditions in a medium amended with Fe(III), Fe(II) accumulated concomitant with a stoichiometric decrease in lactate and an increase in acetate and CO₂. Strain SFB was also capable of respiratory Fe(III) reduction with some unidentified component(s) of Luria broth as an electron donor. In addition to Fe(III), strain SFB could also utilize nitrate, fumarate, or O₂ as alternative electron acceptors. Optimum growth was observed at 30°C and pH 9. Although the optimal salinity for growth was 0%, strain SFB could grow in a medium with up to 15% NaCl by mass. These studies describe a novel alkaliphilic, halotolerant organism capable of dissimilatory Fe(III) reduction under extreme conditions and demonstrate that Bacillus species can contribute to the microbial reduction of Fe(III) in environments at elevated pH and salinity, such as soda lakes.