期刊
FEMS MICROBIOLOGY ECOLOGY
卷 68, 期 2, 页码 223-235出版社
WILEY-BLACKWELL PUBLISHING, INC
DOI: 10.1111/j.1574-6941.2009.00670.x
关键词
dissimilatory metal-reducing bacteria; pyomelanin; electron shuttle; microbial electron transfer; hydrous ferric oxide; iron minerals
类别
资金
- Department of Energy (DOE) Office of Science NABIR/ERSP
- Savannah River National Laboratory Directed Research and Development Program
- Soil and Groundwater Closure Projects of the Savannah River Site funded through DOE-Environmental Management Program
- Battelle Memorial Institute operates PNNL for the DOE [DE-AC05-76RL01830]
- SRNL [DE-AC09-08SR22470]
We hypothesized that Shewanella oneidensis MR-1, a model dissimilatory metal-reducing bacterium, could utilize environmentally relevant concentrations of tyrosine to produce pyomelanin for enhanced Fe(III) oxide reduction. Because homogentisate is an intermediate of the tyrosine degradation pathway, and a precursor of a redox-cycling metabolite, pyomelanin, we evaluated the process of homogentisate production by S. oneidensis MR-1, in order to identify the key steps involved in pyomelanin production. We determined that two enzymes involved in this pathway, 4-hydroxyphenylpyruvate dioxygenase and homogentisate 1,2-dioxygenase are responsible for homogentisate production and oxidation, respectively. We used genetic analysis and physiological characterization of MR-1 strains either deficient in or displaying substantially increased pyomelanin production. The relative significance imparted by pyomelanin on solid-phase electron transfer was also addressed using electrochemical techniques, which allowed us to extend the genetic and physiological findings to biogeochemical cycling of metals. Based on our findings, environmental production of pyomelanin from available organic precursors could contribute to the survival of S. oneidensis MR-1 when dissolved oxygen concentrations become low, by providing an increased capacity for solid-phase metal reduction. This study demonstrates the role of organic precursors and their concentrations in pyomelanin production, solid phase metal reduction and biogeochemical cycling of iron.
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