Fecal Coliforms Lab Report

Abstract Because water serves as vehicles in the transmission of many pathogens, coliforms are commonly used as indicators to monitor the quality of water. I hypothesized that Lake Thoreau would have more fecal coliforms because it is a more stagnant environment meaning more animals can stop their and release their feces, and also the animals that reside there continue to reproduce, leaving no exit for their excretions. By using the MPN test, I was able to detect the coliforms from the fermentation in lactose broths, then with the IMViC test I was able to identify the enteric bacteria colonizing in the water samples. By then end of the experiment, it was apparent that the USM Creek and Leaf River were the two that tested positive for possible
As a result, it is only necessary for us to test and monitor sources that humans come in contact with. Water is very important to humans, and it is abundant in microbes and pathogens. Since fecal matter is the main problem in water, fecal coliforms are commonly used to detect contamination. Some researchers focus on specifics areas and bodies of waters to test, while others even focus on protocols involved in testing water. Discussion of the time consuming process of testing for coliforms is discussed in “Comparison and Recovery of Escherichia coli and Thermotolerant Coliforms in Water.” They describe the process as “laborious and time consuming”, and they illuminate on the fact many variables can affect the results (Alonso, Soriano, Carbajo, Amoros, & Garelick,
With my specific water sample, I then transferred 10 ml of the sample water to the five double strength broths, 1.0 ml to five of the single strength, and 0.1 ml of water to the other five. After incubating them for 24 hours, I observed each tube to see if they obtained a bubble and changed from yellow to red. If the tube turned red it showed it was positive for gas production, and if there was a color change then it indicated the production of acid. With those tubes, I recorded the number from each set that obtained these characteristics. I then took one of the positive testing tubes and inoculated an EMB plate. This test would confir that coliforms were present. After letting the EMB plate incubate for 24 hours, if the agar contained a metallic sheen, then E.coli was present. To test the coliform, I then selected a colony from the agar and inoculated it onto a TSA slant and in a lactose broth. With the TSA slant now being incubated for 24 hours, I then performed a gram stain from it and record my results. From the TSA plates I also inoculated one tube of tryptone broths, one citrate slant, and two MRVP broths with the confirmed coliform. This test is known as the IMViC series. Finally with these tubes inoculated, I was able to measure many different variables. With the two MRVP broths, I first added five drops of methyl red to one culture and to the