environmental micro results

environmental micro results - possibly due to merging...

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Deepika Kaushal Biol 351-916 Environmental Microbiology Experiments RESULTS: Fig 1. Presence of Bacteria in milk Type of Milk Starting appearance Ending appearance Unpasteurized Pale blue Curdled milk, blue ring on top but watery and clear elsewhere Pasteurized Pale blue Foamy milk, faintly blue Fig 2. Number of CFU’s observed in TSA, GYEA and SDA plates as dilution of inoculated soil samples vary Dilution TSA GYEA SDA 10^-1 N/A 200 80 10^-2 144 65 65 10^-3 180 23 21 10^-4 360 17 3 10^-5 120 N/A N/A Fig 3. Presumptive presence of coliforms in water samples with varying dilutions Dilution Positive tests 1 5 (of 10) 10^-1 5 (of 5) 10^-2 3 (of 5) The results of the methylene blue test can be observed in Figure 1. It is clear that the unpasteurized milk housed more bacteria more quickly than the pasteurized milk because the acid caused to indicator to fade and the milk to curdle. In Figure 2 it is shown that in both the GYEA and SDA media the number of CFU’s decreases as the dilution increases. This pattern is not observed for the TSA plates, however,
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Unformatted text preview: possibly due to merging colonies at lower dilutions. Positive tests for the presumptive presence of coliforms was observed in half of the undiluted samples, all of the 10^-1 diluted samples, and three of the five 10^-2 dilution samples. References 1. Leboffe, M. and B. E. Pierce. 2010. Methylene Blue Reductase Test, p. 342-343. Microbiology Laboratory Theory and Application, 3 rd ed., Morton publishing Co, Englewood, CO. 2. Leboffe, M. and B. E. Pierce. 2010. Multiple Tube Fermentation Method for Total Coliform Determination, p. 336-340. Microbiology Laboratory Theory and Application, 3 rd ed., Morton publishing Co, Englewood, CO. 3. Leboffe, M. and B. E. Pierce. 2010. Soil Microbial Count, p. 329-331. Microbiology Laboratory Theory and Application, 3 rd ed., Morton publishing Co, Englewood, CO....
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This note was uploaded on 12/07/2011 for the course BICH 412 taught by Professor Miles during the Fall '09 term at Texas A&M.

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environmental micro results - possibly due to merging...

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