Hixon 1 Concentrations and identities of fecal coliform bacteria from ...

Hixon 8
completed using the techniques described by Lammert et al. (2007), unless otherwise noted. All
tests for differentiation were decided upon after researching various test result differences among
the different fecal coliform bacteria genera Citrobacter, Enterobacter, Escherichia, and
Klebsiella in Bergey’s Manual of Determinative Bacteriology. In order to confirm isolation of a
single bacterium, gram stains were prepared with both a gram positive control Bacillus
megaterium and a gram negative control Psuedomonas aeruginosa for comparison. Gram stains
were also used to measure the length and width of individual bacterial cells and to note cell
morphology using Motic Imaging Software and Swift Cam 5. Bacteria cell measurements were
completed by measuring the lengths and widths of ten separate bacterial cells followed by
calculating the average and the standard deviation. In order to confirm bacterial cell size and
morphology a negative stain was completed. To test if the bacteria were able to produce capsules
(Capsule stain) the bacteria were first grown on sucrose gelatin agar, whereas all other tests used
bacteria samples grown on m-endo agar. The bacteria were tested for their ability to utilize
citrate as a carbon source (Citrate test), to ferment acid by mixed acid fermentation (Methyl-red
test), to conduct butanediol fermentation (Voges-proskauer test), and the ability to grow on
media that inhibits the growth of Gram-positive bacteria and provides a color indicator
distinguishing between organisms that ferment lactose and those that do not (EMB agar). The
bacteria were also tested for motility and indole production (SIM test).
RESULTS AND DISCUSSION
FECAL COLIFORM CFU’s