Cultural and biochemical characters
|
|
|
Cultural characters
-
Very strict anaerobe, grows at an opt.temp. of 370C and pH7.4.
-
It grows on ordinary media and the growth is improved by blood and serum and not by glucose.
-
Surface colonies are very difficult to obtain as the growth has a marked tendency to swarm over the surface of the agar especially if the medium is moist.
-
The swarming nature /spreading can be inhibited by increasing the concentration of agar upto 3% (stiff agar).
-
In this stiff agar individual rhizoid colonies are formed.
-
On blood agar, it develops partially translucent, grayish colonies with filamentous edges giving a fuzzy appearance.
-
On horse blood agar, alpha haemolysis is produced, which later develops into beta haemolysis due to the production of haemolysin (tetanolysin ).
-
C.tetani grows well in Robertson’s cooked meat broth, with turbidity.
-
The meat is not digested, but is turned black on prolonged incubation.
-
In gelatin stab cultures a fir tree type of growth occurs, with slow liquefaction.
-
A greenish fluorescence is produced on media containing neutral red.
Biochemical properties
-
C.tetani has feeble proteolytic property, so it does not ferment any sugars.
-
It forms indole. It is MR and VP negative, nitrates not reduced.
|
Last modified: Monday, 4 June 2012, 4:24 AM
Participants