Bacteria Ecology Essay

745 Words Oct 21st, 2010 3 Pages
Introduction-

This lab experiment serves as a model for community succession using bacterial colonies as the model. A bacterial colony grows from a single bacterium and is composed of millions of cells. Each colony has distinctive colony morphology: size, shape, color, consistency, and color. Community succession is a phenomenon observed in the organizational hierarchy of all living organisms. Community succession is not limited to bacterial colonies, but spans the entire community of life. As the community grows, it changes the environment it inhabits, and the resulting community is different than at the start. As community succession occurs in bacterial colonies pH, odor, color, and consistency changes take place. In this
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Methods- We began the experiment by noting the characteristics of the different milk ages by smell, color, and pH was measured using pH paper. Fresh milk smelled like milk, had a white color, and a pH of 7. 24 hour old milk had a very slight sour smell to it, was still white colored with a pH of 7. Four day old milk had a sour smell, was white with visible chunks, and had a pH of 6. Lastly, four day old milk smelled like sour cream, was yellow colored with white chunks, and had a pH of 5. Once the characteristics of the milk were noted we began to prepare the agar plates for the different milk samples. For cold milk, one agar plate was labeled undiluted, and one plate was labeled “10-1”. 0.5 ml of milk was pipette onto the plate labeled undiluted. 0.1 ml of milk was then pipette onto the plate labeled “10-1”, and the pipette was discarded. Using an alcohol and flame sterilized bent rod, the milk was distributed across the agar plates. The lid was never removed completely, just lifted up enough to allow the rod to thoroughly spread the milk. For 24 hour milk, we prepared four agar plates by labeling them undiluted, “10-1”, “10-2”, and “10-3”. 1 ml of milk was pipette onto the plate labeled undiluted. Then 0.1 ml milk was pipette onto the plate labeled “10-1”. We proceeded to pipette 0.1 ml of milk into the 9 ml water blank labeled “10-2”. The pipette was then discarded and

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