Results

Link to Flowchart
 
Isolate 1 Isolate 5 Isolate 7 Isolate 8 Isolate 10 Isolate 12 Isolate 13
gram positive negative negative negative positive positive negative
voges-proskauer negative negative negative negative negative negative
acid-fast negative negative negative
amylase positive negative
catalase negative positive positive positive positive positive positive
citrate positive positive positive negative negative negative
triple sugar iron negative negative negative negative negative
cytochromoxidase positive positive negative negative negative negative
dextrose positive positive positive positive positive positive
endospore negative negative negative negative negative negative
indole negative negative negative negative negative positive
lactose positive negative negative positive positive positive
lipase negative negative negative negative
methyl red positive negative negative positive positive positive
nitrate negative negative error positive positive positive
sucrose positive negative negative positive positive positive
urea negative negative negative negative

Neisseria macacae - 5
Escherichia coli - 13

This particular isolate was obtained from the very top portion of the mud in the Winogradsky column that was not exposed to artificial light at all times. After performing the Gram stain, we determined this unknown to be a Gram negative rod. We then proceeded with our battery of biochemical tests that we performed on all of our unknowns. For this unknown we performed the following tests: an endospore test, MR-VP, catalase, Simmons citrate, oxidase, indole, lipase, nitrate, urea, and lactose, sucrose and dextrose carbohydrate tests. Because this bacteria came from the top of the mud, we treated it as a facultative anaerobe. We then examined the section in Bergey's Manual for facultatively anaerobic gram negative rods. By comparing our test results with the information contained in these summaries, we were able to eliminate many of the genera listed in this section. We were able to eliminate many genera based on the conditions in which they grew or in which they are found in nature. We determined that this unknown was Escherichi coli. This identification made sense because this bacteria is associated with fecal matter and the contents of our column came from behind a waste-water treatment plant. To be sure we had identified our isolate correctly, we streaked a sample onto an EMB plate. The growth on this plate had a green metallic shine, which is very indicative of E. coli. Therefore, we were convinced that this particular isolate was Escherichi coli.

Evan Haas and Dustin Romine
Discussion