Typical biochemical properties of E.coli are:
- lactose fermentation (red colonies and red coloured agar around colonies on Endo)
- D-mannitol fermentation (red coloured agar and colonies around mannitol tablet)
- negative cellobiose fermentation (colorless colonies and agar on Endo around cellobiose tablet)
- acid from glucose with gas
- hydrogen sulfide negative
- about 50% of all strains ferments sucrose
- Indole production (positive)
- Voges-Proskauer test (negative)
- Simmons citrate (negative)
- Malonate utilization (negative)
- Lysin decarboxylase (typically positive)
- Arginine dihydrolase (typically negative)
- Ornithine decarboxylase (can be positive or negative; more strains are positive)
General description of testing on Endo agar with biochemical slope is here.
Other (more or less) necessary tests for identification are:
Compare these lactose positive isolates with lactose delayed E.coli strains.
Cultivation 24 hours, 37°C in an aerobic atmosphere.