Sources

Isolates

Gram reaction

Morphology under the microscope

Morphology on the plates

1) Cow dung

E. coli

Gram-negative

Rod-like

Metallic sheen on Eosin Methylene Blue (EMB)

2) Human nose swab

S. aureus

Gram-positive

Cocci in clusters

Yellow colonies on Mannitol

3) Soil

Shigella sp.

Gram-negative

Rod-like, non-sporing

Pink colors on MacConkey

4) Soil

Salmonella sp.

Gram-negative

Rod-like, non-capsulate

Dark colors on SSA

5) Soil

Bacillus sp.

Gram-positive

Rod-like

Rough, slightly yellow and opaque on nutrient agar

6) Soil

P. aeruginosa

Gram-negative

Rod-like

Greenish-blue in Nutrient agar

7) Stream water

Strept. sp.

Gram-positive

Cocci in chains

Milky in nutrient agar