1. Propionic acid bacteria Olivia Rasigraf HMC 2012

2. General Gram +, non-sporeforming Facultative anaerobes High GC Secondary fermenters Contain cytochromes Habitats: skin, cheese

3. Incubation at 30°C, dark Lactate-yeast extract broth Isolation

4. “Emmentaler” habitat Lactobacillus casei Streptococcus thermophilus Propionibacterium shermanii CO 2 3 Lactate → 2 Propionate + 1 Acetate + 1 CO 2 + 1 ATP

5. Methylmalonyl-CoA pathway LactatePyruvateAcetyl-CoA Acetate Acetyl-P Oxidative pathway

6. Methylmalonyl-CoA pathway Lactate Pyruvate Acetyl-CoAAcetyl-P Acetate Propionate Fumarate Succinate Malate Oxalacetate Reductive pathway Methylmalonyl-CoA mutase (B12)

7. Acrylyl-CoA pathway Lactate Pyruvate Acetate Acetyl-P Propionate

8. Results All enrichments successful Isolation of single colonies Brown colonies: Methylmalonyl-CoA pathway White colonies: Acrylyl pathway

9. Results

10. Questions?