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Enterococcus colonies (black) growing on BEA. Bile salts are the selective ingredient, while esculin is the differential component. Enterococcus hydrolyze esculin to products that react with ferric citrate in the medium to produce insoluble iron salts, resulting in the blackening of the medium.
A positive test can occur with Enterococcus, Aerococcus, and Leuconostoc. Aesculin will fluoresce under long wave ultraviolet light (360 nm) and hydrolysis of aesculin results in loss of this fluorescence. Enterococcus will often flag positive within four hours of the agar being inoculated.
Enterococcus is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are Gram-positive cocci that often occur in pairs ( diplococci ) or short chains, and are difficult to distinguish from streptococci on physical characteristics alone. [ 2 ]
If an organism does not induce hemolysis, the agar under and around the colony is unchanged and the organism is called non-hemolytic or said to display gamma-hemolysis (γ-hemolysis). Enterococcus faecalis (formerly called "Group D Strep"), Staphylococcus saprophyticus, and Staphylococcus epidermidis display gamma-hemolysis.
Enterococcus raffinosus is a bacterial species of the Gram-positive genus Enterococcus, named for its facultative anaerobic metabolism, including the ability to ferment the trisaccharide raffinose. [1] This mesophilic microaerophile has optimal growth at 37°C in Columbia Blood Medium (agar mixture of trypticase soy and brain heart infusion). [2]
DNA hydrolysis is tested by growing an organism on a DNase Test Agar plate (providing nutrients and DNA) and then checking the plate for hydrolysis. The agar plate has DNA-methyl green complex, and if the organism on the agar does hydrolyze DNA then the green color fades and the colony is surrounded by a colorless zone. [25]
Enterococcus casseliflavus are facultative Gram-positive cocci. They are catalase negative and produce pyrolidonyl arylamidase. They are able to produce acid from many sugars, including L-Arabinose, gluconate, inulin, mannitol, melibiose, trehatol, and xylitol. [2] Similar to other members of the genus, E. casseliflavus is able to hydrolyze ...
Aerobic and anaerobic bacteria can be identified by growing them in test tubes of thioglycolate broth: 1: Obligate aerobes need oxygen because they cannot ferment or respire anaerobically.