Recent discoveries in our lab
- We studied how microbial communities from climate lake sediments promote microbial-influenced Fe0 corrosion when no other electron donor and acceptors are available.
- Clostridia and Methanobacterium were the only groups detected after 11 subsequent transfers solely with zero valent iron (Fe0) as the electron donor.
- Methanobacterium were ineffective corroders in the absence of the acetogens, although they do not use acetate for methanogenesis. These results suggested that acetogens promote hydrogenotrophic methanogenesis in other ways.
- We observed that cell exudates (spent media filtrate extracted during the acetogenesis phase) promoted H2-evolution from Fe0, partially due to thermolabile enzymes and partially due to non-thermolabile constituents released by cells.
- Clostridial [FeFe] hydrogenases were abundant in the metagenome of this corrosive community and may play a role in promoting hydrogenotrophic methanogenesis.
- we tested 11 new co-culture combinations for the possibility to carry out direct interspecies electron transfer. Of these eleven, 8 were capable of syntrophic metabolism.
- We provide the first proof that Methanosarcinas do not require multiheme c-type cytochromes to carry out extracellular electron uptake from syntrophic partners or an electrode.
- the first demonstration of metallic iron corrosion by an environmental Methanosarcina from the Baltic Sea.
- This Methanosarcina competed for electrons from iron with Baltic-acetogenic Sporomusa rather than using the acetate produced by the acetogen. Thus we challenge previous views that corrosion by Methanosarcina’s (often found associated with corroded structures) is rather the result of these methanogens utilizing substrates generated by microorganisms directly accessing the metallic surface.
- this is significant because the Baltic Sea is the dumping ground for radionuclide and chemical waste (including chemical weapons) stored in steel containers. Now we know who may be bio-deteriorating these iron structures in the depths of the Baltic Sea.
- first 1st author paper for Mon – and quite an exciting one
- the first demonstration of electromethanogenesis by Methanosarcina barkeri. However, we learned that not all Methanosarcina capable of DIET could retrieve electrons via elecromethanogenesis from a fixed-potential cathode. We propose that electromethanogenesis at a set cathode-potential cannot match the redox requirements for each type of electroactive Methanosarcina. On the other hand, during DIET, the partner electrogen would modulate its outermembrane cytochrome expression to match the redox requirements of its partner Methanosarcina.
Mads Schou Vammen (directed) and Mon Oo Yee helped create this video a couple of years ago. Although it was intended for a Johnson & Johnson award (which I never got), it gives a fantastic 1-minute overview of my labs’ research vision.