1. Iron-Reducing Bacteria Hopkins Microbiology Course Presented by Ying Lei 22 July 2010

2. Reduction Process 1.Fe 3+ only – ferrihydrite (FeOOH · 0.4H 2 O) – orange/red solid 2.Fe 3+ /Fe 2+ – magnetite (Fe 3 O 4 ) – black, ferromagnetic solid 3.Fe 2+ only – ferrous iron – black, non-magnetic solid

3. Redox Tower Reduced SpeciesOxidized SpeciesRedox Potential (E 0 ’) [CH 2 O]CO 2 -470 mV Fe 2+ αFe 2 O 3 -280 mV Fe 2+ αFeOOH-280 mV CH 4 CO 2 -250 mV H2SH2SSO 4 2- -220 mV Fe 2+ γFeOOH-100 mV Fe 2+ Fe(OH) 3 0 mV Fe 2+ Fe 3+ +770 mV H2OH2OO2O2 +820 mV CH 3 CH(OH)COO - + 12 FeOOH + 4 H 2 O  3 HCO 3 - + 12 Fe 2+ + 22 OH - lactate C 0 iron (III) Fe 3+ CO 2 C 4+ iron (II) Fe 2+ Canfield et al, Aquatic Geomicrobiology (2005)

4. Enrichment Medium ComponentAmountPurpose basal marine mineral medium1 Lbasic salts sodium lactate4.5 g (30 mM)carbon source NaHCO 3 30 mL (30 mM)pH buffer iron (III) hydroxide30 mL (40 mM)ferric iron source 7-vitamin solution30 mLcofactors SL 101 mLtrace elements Se-Wo solution1 mLtrace elements Adjust to pH 7.2 in Pfennig bottles and incubate under anoxic conditions. Hopkins Microbiology Course (2010)

5. Sample Collection Canfield et al, Aquatic Geomicrobiology (2005)

6. Sample Collection

7. Successful Enrichments Marcus

8. Thank You All Instructors and Students Chris Marcus Blanca

9. Additional Slides

10. Iron Solubility OzCoasts (www.ozcoasts.org.au)