|
|
 |
 |
|
 |
|
| Positive reaction: Bacillus cereus. |
|
|
| Negative reaction: Bacillus sphaericus. |
|
|
The purpose of this test is to determine whether an organism can hydrolyse starch enzymatically. After incubation the medium, which contains starch, is flooded with aqueous Lugol's iodine. Unhydrolysed starch in the medium is coloured dark blue. A colourless zone around the streak indicates that hydrolysis has taken place.
The picture below shows the agar with Bacillus sphaericus before Lugol's iodine is added.
Click on the picture to see an enlarged version. |
|
|
|
|
|
