Iron-Reducing Bacteria

Hopkins Microbiology Course

Presented by Ying Lei22 July 2010

Reduction Process

1. Fe3+ only– ferrihydrite (FeOOH · 0.4H2O)– orange/red solid

2. Fe3+/Fe2+

– magnetite (Fe3O4)– black, ferromagnetic solid

3. Fe2+ only– ferrous iron– black, non-magnetic solid

Redox TowerReduced Species Oxidized Species Redox Potential (E0’)

[CH2O] CO2 -470 mV

Fe2+ αFe2O3 -280 mV

Fe2+ αFeOOH -280 mV

CH4 CO2 -250 mV

H2S SO42- -220 mV

Fe2+ γFeOOH -100 mV

Fe2+ Fe(OH)3 0 mV

Fe2+ Fe3+ +770 mV

H2O O2 +820 mV

CH3CH(OH)COO- + 12 FeOOH + 4 H2O 3 HCO3- + 12 Fe2+ + 22 OH-

lactateC0

iron (III)Fe3+

CO2

C4+

iron (II)Fe2+

Canfield et al, Aquatic Geomicrobiology (2005)

Enrichment MediumComponent Amount Purpose

basal marine mineral medium 1 L basic salts

sodium lactate 4.5 g (30 mM) carbon source

NaHCO3 30 mL (30 mM) pH buffer

iron (III) hydroxide 30 mL (40 mM) ferric iron source

7-vitamin solution 30 mL cofactors

SL 10 1 mL trace elements

Se-Wo solution 1 mL trace elements

Adjust to pH 7.2 in Pfennig bottles and incubate under anoxic conditions.

Hopkins Microbiology Course (2010)

Sample Collection

Canfield et al, Aquatic Geomicrobiology (2005)

Sample Collection

Successful Enrichments

Marcus

Thank You

All Instructors and Students

ChrisMarcusBlanca

Additional Slides

Iron Solubility

OzCoasts (www.ozcoasts.org.au)