Propionibacterium(redirected from Propionibacterium acnes)
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a nonspore-forming, gram-positive, and nonmotile rod that measures 0.5–0.8 × 1.0–1.5 μ. In young cultures, the rods are twisted and slightly branched, while in older cultures they are coccoid.
Propionibacteria form yellow, orange, or red colonies and grow under both aerobic and anaerobic conditions. They are nonpathogenic and live in dairy products (except milk) and in the rumen and intestine of ruminants. Propionibacteria are the causative agents of propionic-acid fermentation. They ferment glucose, lactose, and other carbohydrates; they also ferment some alcohols, forming propionic and acetic acids and CO2 as a result. Enzymes that contain propionibacteria are used in cheese-making: the openings and the flavor and aroma of Swiss cheese are largely determined by propionic-acid fermentation. Propionibacteria are used in the microbiological synthesis of vitamin B12. Various nutrient media that contain cobalt are used to grow propionibacteria.
A. A. IMSHENETSKII