Test Reagents Used in Microbiology Laboratory
Preparation and composition of commonly used reagents for routine biochemical and laboratory tests.
Catalase Reagent — 3% H2O2
| Component | Quantity |
|---|---|
| Hydrogen peroxide | 3 mL |
| Distilled water | 97 mL |
Preparation
To 97 mL of distilled water, add 3 mL of hydrogen peroxide and mix well.
Oxidase Reagent
The oxidase reagent is impregnated in Whatman's No. 1 filter paper.
| Component | Quantity |
|---|---|
| Tetramethyl-p-phenylenediamine dihydrochloride | 1 g |
| Distilled water | 100 mL |
Preparation
Dissolve 1 g of tetramethyl-p-phenylenediamine dihydrochloride in 100 mL of distilled water.
Soak strips of Whatman's No. 1 filter paper in the reagent solution and drain them for approximately 30 seconds.
Freeze-dry the strips and store them in a tightly sealed dark bottle with a screw cap.
Kovac's Indole Reagent
| Component | Quantity |
|---|---|
| Isoamyl alcohol | 30 mL |
| p-Dimethylaminobenzaldehyde | 2.0 g |
| Hydrochloric acid | 10 mL |
Preparation
Dissolve 2 g of p-dimethylaminobenzaldehyde in 30 mL of isoamyl alcohol and transfer the solution to a clean brown bottle.
Add 10 mL of concentrated hydrochloric acid and mix well.
Methyl Red Solution
| Component | Quantity |
|---|---|
| Methyl red | 0.05 g |
| Ethyl alcohol (absolute) | 28 mL |
| Distilled water | 22 mL |
Preparation
Dissolve 0.05 g of methyl red in 28 mL of absolute ethanol and transfer the solution to a clean brown bottle.
Add 22 mL of distilled water and mix well.
Solution A
| Component | Quantity |
|---|---|
| α-Naphthol | 5.0 g |
| Ethyl alcohol (absolute) | 100 mL |
Preparation
Dissolve 5 g of α-naphthol in 25 mL of distilled water and transfer the solution to a clean brown bottle.
Make the final volume up to 100 mL by adding distilled water.
Solution B
| Component | Quantity |
|---|---|
| Potassium hydroxide (KOH) | 40.0 g |
| Distilled water | 1000 mL |
Preparation
Dissolve 40 g of potassium hydroxide in 25 mL of distilled water and transfer the solution to a clean brown bottle.
Make the final volume up to 100 mL by adding distilled water.
| Component | Quantity |
|---|---|
| Sodium deoxycholate | 10 g |
| Distilled water | 100 mL |
Preparation
Prepare a 10% solution of sodium deoxycholate by adding 10 g of sodium deoxycholate powder to 100 mL of distilled water.
Transfer the solution to a clean brown bottle and autoclave.
| No. | Test | Reagent |
|---|---|---|
| 1 | Catalase | 3% Hydrogen peroxide |
| 2 | Oxidase | Tetramethyl-p-phenylenediamine dihydrochloride |
| 3 | Indole | Kovac's reagent |
| 4 | Methyl Red | Methyl red solution |
| 5 | Voges-Proskauer | Barritt's reagents — Solution A and B |
| 6 | Bile Salt | 10% Sodium deoxycholate |
Comments