Quantification of Microbes in Milk and Water

Naomi Hall


BSC 381L H003

Group: Megan Baker, Katie Coe and Meagan Williams


Coliforms are gram bad bacteria generally found in the intestines of birds and mammals and therefore are the most generally utilized symptoms of waste contamination. The objective of this experiment was to check various normal water and dairy samples for the presence of coliforms, specifically waste coliforms. It was expected that fecal coliforms would be found in all water sources except for the bottled and tap water. It was as well expected that there would be little to no coliforms inside the milk that were pasteurized as compared to the raw milk which will had not been pasteurized. To test the sample we performed a great MPN (most probable number) test and a series of tests including an natura production evaluation, Methyl-red evaluation, Voges-Proskauer test and a citrate utilization check. This series of tests is often referred to as the IMViC. To evaluate the dairy we performed both a typical plate depend test and a coliform plate count check. After performing all testing on the water trials it was found that fecal coliforms are not found in the bottled or tap water but were seen in the different water trials and that one of these water selections was confirmed to contain Escherichia coli especially. After carrying out all testing on the dairy samples it was found that every samples except for whole milk included microbes with raw dairy containing the greatest number of bacterias. It was also available that organic milk was your only milk sample that contained coliforms.


Normal water is known to serve as a method of transmitting for pathogens. This is why checks are executed on our water to detect the presence of indicator microorganisms which may be associated with pathogenic creatures (Littlejohn, 2010). Specifically, water is analyzed for the presence of coliforms which are bacteria (often referred to as enteric bacteria due to being through the Enterobacteriaceae category of bacteria) typically found in the intestines of birds and mammals. This sort of bacteria does not produce endospores and levain lactose which in turn produces acid and gas within forty-eight hours of testing. Waste contamination of water can easily contribute to harmful pathogens being in water sources. Fecal coliforms reveal that the drinking water may have pathogens seen in the intestinal tract such as At the. coli which is often used in determining whether water is safe for human being consumption or perhaps not (Littlejohn, 2010). A multiple tube fermentation test out, commonly known as a most possible number (MPN) test is a common way to detect coliforms in normal water by injecting lactose broths with a sample of the water sample getting tested, in the event that bubbling or perhaps color change appear, it can be assumed that coliforms can be found in the water sample. To verify whether or not the drinking water sample consists of coliforms, a sample of the normal water is then placed on EMB agar which includes lactose, then performing a gram discoloration to retest for fermentation of lactose. To differentiate between the different bacteria of the Enterobacteriaceae friends and family, a series of assessments called the IMViC are performed boating samples and determine whether or not the bacteria is a fecal coliform (Littlejohn, 2010).

Due to the various nutrients in milk, this makes it an excellent place for microbes to grow which usually increases the likelihood of microbes growing at a fast rate triggering spoilage with the milk – increasing the chance of spreading disease. Like drinking water, milk can easily contain hazardous pathogens which might be due to fecal contamination (Littlejohn, 2010). When milk is definitely pasteurized to reduce pathogenic microorganisms which cause spoilage and disease, pasteurization would not sterilize milk. Two testing can be performed on milk examples to determine in case the milk contains bacteria of course, if the bacterias found in the milk happen to be fecal coliforms or not. One is a normal plate count which will let bacterial CFUs to be...

Offered: Littlejohn, C. (2012). Microbes in Health and Disease (microbiology lab manual). (p. 41-52). Kendall Quest Publishing Organization. Dubuque, Iowa.

Analyse Various ways in Which You Might Establish Ground Rules with Your Learners, Which Underpin Behaviour and Respect for Others Essay