Litmus milk is a complex medium that can potentially distinguish many species of bacteria. Litmus milk has several components that can be metabolized: lactose (milk sugar); casein (milk protein); and litmus (a pH indicator). If lactose is fermented, the solution should turn pink. If gas is produced during fermentation, you may be able to see bubbles or cracks in the milky medium. If lactose is not fermented and proteins are metabolized instead, the solution will become alkaline and turn blue in color. If casein is digested, the milk will coagulate to form a curd (a solid). Casein may be metabolized all the way down to individual amino acids. This process, called peptonization, results in a clear (not milky) liquid that is usually brown in color. Finally, the litmus may be reduced and become colorless. The culture will then look milk white.
1. Litmus Milk Broth 2. Bunsen Burner 3. Inoculation Loop 4. Nutrient slant 5. Goggles 6. Lab Coat 7.
1. Get an Inoculation loop and sterilize it using the Bunsen burner. 2. Take bacteria from your nutrient slant on inoculation loop 3. Inoculate a litmus milk tube with the bacteria. 4. Incubate for 72 hours; observe results every 24 hours for 3 days.