Transcript Isolation of Mn(II)-oxidizing Bacteria HMC 2010 short presentation Maren Emmerich Why? How? Results • Mn 2nd most abundant transition metal in Earth‘s crust • Mn redox.

Isolation of Mn(II)-oxidizing Bacteria
HMC 2010 short presentation
Maren Emmerich
Why?
How?
Results
• Mn 2nd most abundant transition metal in Earth‘s crust
• Mn redox cycling environmentally important
• Mystery of microbial Mn2+ oxidation:
Not used for energy metabolism, why else?
• 3 models of Mn2+-oxidizing bacteria:
- outer-membrane-associated multicopper-oxidases in
Leptothrix discophora & 2 Pseudomonas putida strains
- multicopper oxidase in marine Bacillus spores
- marine a-proteobacteria
Ideas
Why?
How?
Results
• Mn 2nd most abundant transition metal in Earth‘s crust
• Mn redox cycling environmentally important
• Mystery of microbial Mn2+ oxidation:
Not used for energy metabolism, why else?
• 3 models of Mn2+-oxidizing bacteria:
- outer-membrane-associated multicopper-oxidases in
Leptothrix discophora & 2 Pseudomonas putida strains
- multicopper oxidase in marine Bacillus spores
- marine a-proteobacteria
• Mn2+-oxidizers found in phylogenetically diverse groups
Ideas
Why?
How?
I) Sampling at Elkhorn Slough
Results
Ideas
II) Streak out 2 x 100 µl on K medium
• complex medium
• enriched with 100 µM MnCl2
III) Aerobic incubation on labbench for 1-3 weeks…
Why?
How?
Results
Ideas
Restreak brown colonies
Why?
How?
Results
Ideas
Leucoberbelin blue test for MnO2
Why?
How?
Results
Ideas
Some statistics
•
•
•
•
34 samples from Kirby Park, Strawberry Mat, HMS beach
10 plates with brown colonies after 1-3 weeks (AVG: 1.6)
4 leucoberbelin positives after restreak
No isolate yet
Successful sampling sites
Kirby Park
Kirby Park
HMS beach
Why?
How?
Results
Ideas
• Phylogeny of Mn2+-oxidizers?
Sequence 16S rRNA genes of positive colonies
G
G
• Do
g isolates grow in liquid? Under which conditions?
g Inoculate minimal media and add different
g electron donors & acceptors, incubate +/- light…
g
G
2+ oxidation?
• Energetical
benefit
of
Mn
g
Compare growth yields of isolates
grown +/- manganese
• More ideas?
Thank you!
Why?
How?
Results
Standard redox potentials at pH = 7
2H++ 2eNAD+ + 2H+ + 2eS + 2H+ + 2eSO4-2 + 8H+ + 8epyruvate + 2H+ + 2eFAD + 2H+ + 2ecytochrome b (Fe3+) + eubiquinone + 2H+ + 2ecytochrome c (Fe+3) + eNO3- + 2H+ + 2eNO2- + 8H+ + 6eFe+3 + eO2 + 4H+ + 4e-
H2
NADH + H+
H2S
H2S
lactate
FADH + H+
cytochrome b (Fe+2)
ubiquinone H2
cytochrome c (Fe+2)
NO2- + H2O
NH4
Fe+2
2H2O
-0.42
-0.32
-0.274
-0.22
-0.185
-0.18
0.075
0.10
0.254
0.421
0.44
0.771
0.815
Idea
• Reaction: Mn2+ + 0.5 O2 + H2O → MnO2 + 2H+
• G◦ = −80.8 kJ/mole; Mn E◦ = + 0.419 V