My partner and I drew number eight for the unknown experiment. Throughout the semester, we did many tests to find out what our bacterium was. We discovered that our bacterium was called Serratia marcescens. At the beginning of the semester we made a stock culture prep that we could continuously use to find out our bacterium. Also, in case anything happened to the stock culture prep we made a reserved slant. We did many tests throughout the semester to find out the cell shape, arrangement, size, motility, oxygen requirements, and optimum temperature of our bacterium. We found out that our organism was rod shaped after making a quadrant streak plate. In exercise 26, Temperature: Effects on Growth, we measured the effects of various temperatures on pigment production and growth rate. We inoculated three different organisms with different temperatures in nutrient broth and nutrient agar slants. In this experiment we found that our organism, Serratia marcescens, produces prodigiosin, which only grows in certain temperature ranges. After running these test, we found out that our organism’s …show more content…
We determined that our bacterium tested positive for glucose, sucrose, and mannitol, and negative for lactose by performing sugar fermentation tests. Our Voges-Proskauer and Methyl Red test both determined that our bacterium was positive. I feel like the most beneficial experiments that we performed during this lab were the oxidation and fermentation tests. We tested to see if cytochrome oxidase was present in our bacterium. This test showed us that Serratia marcescens was negative for the enzyme cytochrome oxidase, which helped us differentiate our bacterium from many others. Another experiment that eliminated many other bacteria from Serratia marcescens were the tests that showed that starch, casein, and fat were all negative in our unknown