Document Detail


Iron-reducing bacteria accumulate ferric oxyhydroxide nanoparticle aggregates that may support planktonic growth.
MedLine Citation:
PMID:  23038172     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Iron-reducing bacteria (FeRB) play key roles in anaerobic metal and carbon cycling and carry out biogeochemical transformations that can be harnessed for environmental bioremediation. A subset of FeRB require direct contact with Fe(III)-bearing minerals for dissimilatory growth, yet these bacteria must move between mineral particles. Furthermore, they proliferate in planktonic consortia during biostimulation experiments. Thus, a key question is how such organisms can sustain growth under these conditions. Here we characterized planktonic microbial communities sampled from an aquifer in Rifle, Colorado, USA, close to the peak of iron reduction following in situ acetate amendment. Samples were cryo-plunged on site and subsequently examined using correlated two- and three-dimensional cryogenic transmission electron microscopy (cryo-TEM) and scanning transmission X-ray microscopy (STXM). The outer membranes of most cells were decorated with aggregates up to 150 nm in diameter composed of ∼3 nm wide amorphous, Fe-rich nanoparticles. Fluorescent in situ hybridization of lineage-specific probes applied to rRNA of cells subsequently imaged via cryo-TEM identified Geobacter spp., a well-studied group of FeRB. STXM results at the Fe L(2,3) absorption edges indicate that nanoparticle aggregates contain a variable mixture of Fe(II)-Fe(III), and are generally enriched in Fe(III). Geobacter bemidjiensis cultivated anaerobically in the laboratory on acetate and hydrous ferric oxyhydroxides also accumulated mixed-valence nanoparticle aggregates. In field-collected samples, FeRB with a wide variety of morphologies were associated with nano-aggregates, indicating that cell surface Fe(III) accumulation may be a general mechanism by which FeRB can grow while in planktonic suspension.
Authors:
Birgit Luef; Sirine C Fakra; Roseann Csencsits; Kelly C Wrighton; Kenneth H Williams; Michael J Wilkins; Kenneth H Downing; Philip E Long; Luis R Comolli; Jillian F Banfield
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2012-10-04
Journal Detail:
Title:  The ISME journal     Volume:  7     ISSN:  1751-7370     ISO Abbreviation:  ISME J     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-01-22     Completed Date:  2013-11-14     Revised Date:  2014-02-04    
Medline Journal Info:
Nlm Unique ID:  101301086     Medline TA:  ISME J     Country:  England    
Other Details:
Languages:  eng     Pagination:  338-50     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Bacteria / metabolism
Biodegradation, Environmental
Colorado
Ferric Compounds / metabolism*
Geobacter / growth & development*,  metabolism
Groundwater / microbiology*
Iron / metabolism
Microscopy, Electron
Minerals / metabolism
Nanoparticles*
Oxidation-Reduction
Spectrum Analysis
Water Microbiology
Chemical
Reg. No./Substance:
0/Ferric Compounds; 0/Minerals; 39473-89-7/ferrihydrite; E1UOL152H7/Iron
Comments/Corrections

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