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?