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Litmus Milk Procedural

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Litmus Milk Procedural
Sarah St. Vincent
Olivia Almeida
December 10, 2012
Biomedical

LITMUS MILK

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.
Materials:
1. Litmus Milk Broth 2. Bunsen Burner 3. Inoculation Loop 4. Nutrient slant 5. Goggles 6. Lab Coat 7. Incubator
Procedure:
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.
Lab safety: 1) Always have lab coat on 2) Always have hair tied back 3) Always have safety goggles on 4) No loose clothing 5) No loose jewelry
For our hypothesis we had based it of the chart. We had thought our unknown bacteria is E coli so we said that we wanted to get and acid, curd reduction. Thus, making our hypothesis correct.
Glossary:
1. Metabolized - the sum of the physical and chemical processes in an organism by which its material substance is produced, maintained, and destroyed, and by which energy is made available. 2. Lactose - milk sugar 3. Casein - milk protein 4. Litmus

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