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Propionic acid bacteria
Olivia RasigrafHMC 2012
General
• Gram+, non-sporeforming• Facultative anaerobes• High GC• Secondary fermenters• Contain cytochromes• Habitats: skin, cheese
Incubation at 30°C, darkLactate-yeast extract broth
Isolation
“Emmentaler” habitat
Lactobacillus casei
Streptococcus thermophilusPropionibacterium shermanii
CO2
3 Lactate → 2 Propionate + 1 Acetate + 1 CO2 + 1 ATP
Methylmalonyl-CoA pathway
Lactate Pyruvate Acetyl-CoA AcetateAcetyl-P
Oxidative pathway
Methylmalonyl-CoA pathway
Lactate Pyruvate Acetyl-CoA Acetyl-P Acetate
Propionate
Fumarate
Succinate
Malate
Oxalacetate
Reductive pathway
Methylmalonyl-CoA mutase (B12)
Acrylyl-CoA pathway
Lactate Pyruvate AcetateAcetyl-P
Propionate
Results
• All enrichments successful• Isolation of single colonies
Brown colonies: Methylmalonyl-CoA pathway
White colonies: Acrylyl pathway
Results
Questions?