Brochothrix thermosphacta
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| (McLean & Sulzbacher 1953) Sneath & Jones 1976 |
Brochothrix thermosphacta is a gram-positive , rod-shaped, immobile , facultatively anaerobic and psychrotrophic microorganism with importance for food microbiology .
features
Appearance
Brochothrix thermosphacta is a gram-positive , rod-shaped and immobile bacterium . The length of the cells varies from short rods to long filaments, the width is around 0.6 µm.
Growth and metabolism
The growth is facultative anaerobic . After 24 hours of incubation, only little growth can be seen on common nutrient media , but small, round, smooth and shiny colonies can be seen after 2-3 days . Their diameter is 1.0 to 1.5 mm, they are not particularly colored. There is no hemolysis on blood agar . Growth takes place optimally at 20–22 ° C, but growth can also be seen after seven days at 0–1 ° C, but no growth occurs at 37 ° C. This means that the species is more likely to be characterized as psychrotolerant ( psychrotrophic ) than as psychrophilic .
The catalase test is positive. There is no formation of hydrogen sulfide (H 2 S), nitrate cannot be reduced, gelatine and urea are not hydrolyzed , citrate cannot be used. The following carbohydrates are broken down with the formation of acid, but without visible gas formation: The monosaccharides arabinose , glucose and xylose ; the disaccharides lactose , sucrose , maltose and cellobiose ; the sugar alcohols mannitol and dulcitol as well as starch as polysaccharide . During the fermentative breakdown ( fermentation ) of these carbohydrates, L - (+) - lactic acid is formed as the predominant product.
Brochothrix thermosphacta is not particularly heat resistant . At 55 ° C, killing takes place after a maximum of 10 minutes, at 63 ° C most strains are killed after 3 minutes, the more resistant ones after 5 minutes.
Occurrence
Brochothrix thermosphacta was discovered in fresh pork sausage.
meaning
Due to its ability to grow at 4 ° C and without oxygen at higher concentrations of carbon dioxide , Brochothrix thermosphacta often spoils prepackaged or vacuum packed meat and meat products. In the process, it forms volatile substances acetoin , diacetyl (aerobic) or, under anaerobic conditions, lactic acid and ethanol . SIN agar (streptomycin inositol neutral red agar) can be used for detection.
Systematics
Brochothrix thermosphacta was previously referred to as " Microbacterium thermosphactum " (McLean and Sulzbacher 1953), it is a synonym . The epithet B. thermosphacta roughly means "is killed by heat". The genus Brochothrix was previously counted among the lactic acid bacteria , but belongs to the Listeriaceae family (as of 2018).
Individual evidence
- ^ A b c Jean Euzéby, Aidan C. Parte: Genus Brochothrix. In: List of Prokaryotic names with Standing in Nomenclature Systematics of Bacteria (LPSN) . Retrieved April 7, 2018 .
- ↑ a b c d e RA McLean, WL Sulzbacher: Microbacterium thermosphactum, spec. nov .; a nonheat resistant bacterium from fresh pork sausage. In: Journal of Bacteriology. Volume 65, Number 4, April 1953, pp. 428-433, PMID 13069397 , PMC 169546 (free full text).
- ^ Samuel Kilcher, Martin J. Loessner and Jochen Klumpp: Brochothrix thermosphacta Bacteriophages Feature Heterogeneous and Highly Mosaic Genomes and Utilize Unique Prophage Insertion Sites . In: Journal of Bacteriology . tape 192 , no. 20 , 2010, ISSN 0021-9193 , p. 5441-5453 , doi : 10.1128 / JB.00709-10 , PMID 20709901 .
- ^ Günter Klein: Microtheque / basic work. Behr, Hamburg 2007, ISBN 978-3-89947-372-8 , pp. 6 .
- ^ Jean Euzéby, Aidan C. Part: Phylum Firmicutes. In: List of Prokaryotic names with Standing in Nomenclature Systematics of Bacteria (LPSN) . Retrieved April 7, 2018 .