Adjust pH to 7.2 with 1 N NaOH. Bring volume to 1 liter with distilled water. Sterilize 15 min at 121°C. Store in refrigerator.
Dilution blanks Take 1.25 ml of above stock solution and bring volume to 1 liter with distilled water. Dispense into bottles to 90 or 99 ± 1 ml. Sterilize 15 min at 121°C.
R12. Catalase Test Pour 1 ml 3% hydrogen peroxide over growth on slant culture. Gas bubbles indicate positive test. Alternatively, emulsify colony in l drop 3% hydrogen peroxide on glass slide. Immediate bubbling is positive catalase test. If colony is taken from blood agar plate, any carry-over of red blood cells can give false-positive reaction.
Rl2a. Chlorine Solution, 200 ppm, Containing Q.1% Sodium Dodecyl Sulfate Commercial bleach (5.25% sodium hypochlorite) 8 ml Distilled water containing 1 g sodium dodecyl sulfate 992 ml
Dissolve 1 g sodium dodecyl sulfate in 992 ml distilled water. Add 8 ml commercial bleach and mix well. Make immediately before use.
R13. 0.05 M Citric Acid (PH 4.0) Citric acid (monohydrate)10.5 g Double distilled water to make l liter
Dissolve citric acid in 900 ml distilled water. Adjust pH to 4.0 with 6 M NaOH and dilute to 1 liter. Store in refrigerator.