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Propionic acid Bacteria Enrichment

Propionic acid Bacteria Enrichment. Bruno Fonseca Hopkins Microbiology Course 2010 Monterey , CA, USA .

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Propionic acid Bacteria Enrichment

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  1. PropionicacidBacteriaEnrichment Bruno Fonseca HopkinsMicrobiologyCourse 2010 Monterey, CA, USA

  2. Propionic acid has numerous applications in various food and chemical industries, and is mainly used as a mold inhibitor for animal feeds and as a preservative for foods such as cheeses and baked goods. • Propionic acid is produced mainly by Propionibacterium, but this isn’t the only genera that has this ability: • Propionibacteriumare slow-growing, non-sporeforming, rod-shaped, Gram-positive, anaerobic heterotrophic bacteria. • These microorganisms usually possess catalase. • Ferment lactate and produce acetate, propionate and CO2. • If pH value is below 4.5 there is practically no growth • Clostridium • Veillonella • Selenomonas

  3. First observed in the cheese manufacture, dating back to the beginning of the nineteenth century. • Propionicacid is what partly gives Swiss cheese its characteristic flavor and the CO2 is what produces its characteristic holes. • Propionibacteriumhave been granted GRAS (Generally Recognized As Safe) status by FDA. • However, certain species of Propionibacteriumare known for causing infections including the common skin disease acne vulgaris (caused by P. acnes). • van Niel named some species of Propionibacterium.

  4. Day 1 • Inoculum: • Swiss-cheese • Media: • 40 gr Sodium-lactate • 5 gr Yeast extract • Selective technique: • Lactate as the major carbon/electron source • Anaerobic growth (screw capped tubes gently bubbled with CO2) • Incubate at 30 ºC

  5. 2 days later … • Streakedthemilk-whitegrowthinto a lactate-CaCO3agarplate • Incubatedat 30ºC inananaerobicjar

  6. 1 week later … Brownish-redcoloredcolonies Probablydue to having a cytochromesystem CatalaseActivitytest: Catalase 2H2O2 2H2O + O2 Production of O2 Bubbles

  7. Looking at them under the microscope… Smallnon-motilerod-shappedbacteria

  8. Propionic acid formation Dicarboxylicacidpathway: NAD+ Lactate LactateDehydrogenase NADH methylmalonyl-CoAmutase Vitamin B12 Succinate

  9. Propionic acid formation Acrylatepathway: CoA-SH CoA-SH ThispathwayoccursnamelyinClostridiumpropionicum

  10. Propionic acid formation Acrylatepathway:

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