Unknown Bacteria Lab Report

1467 WordsMay 14, 20086 Pages
Introduction The purpose to this lab was to isolate and identify two unknown bacteria from a mixed culture provided to us by our instructor. This study was done by applying all of the methods that have been instructed on thus far in microbiology laboratory class. Each test performed, provided us with some key information about the unknown microbes in question and how the bacteria function. Materials and Methods Over a two week period, eight prepared types of test media were provided to identify the assigned unknown mixed cultures. Not all of these tests were performed on every culture, as some were used only for gram positive or gram negative bacteria. The tests performed and what constituted a positive or negative test are as…show more content…
For the final test, two drops of hydrogen peroxide (H2O2) were placed on the isolated colony of the BHIA medium, observed immediate formation of bubbles, as O2 was produced indicating a positive test for catalase. Final lab day four; the test media were collected for explanation and interpretation, the results are as listed: Gram Negative Enterobacteriaceae DrySlide test card Positive (+) slide took on a pink color Enterotube II –identification system • Glucose Positive (+) color changed from red to yellow • Lysine Positive (+) color changed from yellow to purple • Ornithine Negative (-) no color change • H2S Negative (-) no color change • Indole Positive (+) • Adonitol Negative (-) no color change • Lactose Positive (+) color changed from red to yellow • Arabinose Positive (+) color changed from red to yellow • Sorbitol Positive (+) color changed from red to yellow • Dulcitol Negative (-) no color change • Phylalanine- Negative (-) no color change deaminase • Urea Negative (-) no color change • Citrate Negative (-) no color change *Unknown 041 Gram Negative is Escherichia coli Gram Positive Cocci • BHIA (color) White • BHIA(colony size) Small • Catalase Positive (+)formation of bubbles observed • DNase Negative (-) no visible reaction to HCL • MSA (growth) Positive

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