Title: coliform test
Date:
Student no.
Name:
Experimental Objectives:
The purpose of the experiment was to test the coliform in a sample of drinking water provided
Experimental Theory:
The 3M petrifilm is an E.coli count plate that is reliable and is always a ready medium used in enumerating coliforms such as E.coli and others. It has a violet-red bile nutrient, a glucuronidase indicator, cold-water-soluble to identify the coliforms. Tetrazolium indicator is also present, which helps in enhancing the visualization of gram coliform negative bacteria. Coliforms usually ferment lactose that is contained in the medium, releasing a gas. The coliform colony traps the produced gas and permits the differentiation of coliform bacteria, particularly from the other gram-negative bacteria.
Additionally, indicator-nutrient is usually cleaved by using a target microbe metabolizing nutrient and freeing the indicator by expressing a specific color. The total coliform is identified as well as detected using the sample in almost twenty-four hours or less through inoculation of reagent by use of a sample of water hence incubating. Coliform bacteria should be monitored as they are microbes to determine if the water used for drinking from the system of distribution is potentially associated with pathogens. The ingestion of any pathogens from drinking water might result in hepatitis, paralysis, gastroenteritis, as well as other negative impacts of health. Most coliform bacteria are found on the surface of water or on soil and can even occur on someone’s skin. A considerable number of particular types of coliform bacteria may be found in waste from animals and humans.
Reagent and Experimental apparatus:
- 3M petrifilm reagent
- Paddy water sample
- Incubator
- 7 CFU/100ml
Experimental Methods
The 3M petrifilm count plate was placed on a flat surface. The top film was then lifted, and a 1ml sample was dispensed at the center of the bottom film. Additionally, the top film was slowly rolled down to the sample to prevent the entrapment of the air bubbles. Next, the sample was then distributed evenly well within the circular by use of a gentle downward pressure that was applied at the center of the spreader. Last but not the least, the plate was incubated but using a horizontal position with a clear side facing up.
Results:
There was the incubation of the provided petrifilm at a temperature of 44 .5 degrees. Some blue colonies could be seen on the plate together with entrapped gas. Also, there was the presence of other red as well as being associated with bubbles of gas. Colonies that were not related to the gas were not counted to be coliforms. Also, colonies that are not blue in color were not counted as E. coli. The coliforms counting was composed of blue and red colonies that were associated with the gas at forty-eight hours.
Discussion:
The colonies they were found on the foam were not counted since they are usually removed from a medium selective influence. The growth area that was circularly estimated to be twenty centimeters squared. There was no estimation done since the developed colonies were not more than one hundred and fifty. One has to count a representative of the total number of squares and multiply by a suitable number to get an estimated count for the growth area. Moreover, due to the high concentration of E. coli, the growth area was mm in a bluish color. Also, because of high levels of coliforms like non-E. coli resulted in the area becoming dark reddish in color. Because of the results obtained, there was no further dilution of the sample for a more accurate count.
Coliform bacteria have been highly used as an indication of fecal contamination for both marine and freshwaters. Particular members of the coliform group usually live outside the gastrointestinal tract within the environment and may result in an indication that is false based on fecal contamination. The 3M petrifilm reagent is used simultaneous detections of the number of coliforms as well as E. coli found in water. Bacteria should be observed using a UV light for them to be detected. However, bacteria tend to be assembled from the surfaces, especially when there are high levels of flavin. In case the water has some background color, it should be further examined using the dilution process. Testing of coliform bacteria is termed as the leading indicator of “portability” and the suitability of drinking water consumption. The reason being, it involves measuring concentrated total coliform bacteria that are related to the possible presence of diseases.
Coliform bacteria are then treated by the use of disinfection and also filtration. Using filtration alone might not actually be ultimately an effective means, although it might enhance the performances of disinfectants through the removal of sediment sheltering the present bacteria. Sample collections are mainly done directly and carefully to the bottle being used to avoid any contamination. Some samples vary the duration in the incubator, but it should be between twenty to forty-eight hours. It has been determined that testing of the total coliform bacteria is inexpensive than the cost of determining concentrations or presence of the cryptosporidium, viruses, and Giardia.
References
“Bacteriology102 -Coliforms”. Splammo.Net, 2020, https://www.splammo.net/bact102/102coliforms.html.
Mr. Brian Oram, PG. “Water Research Center – Well Water Testing Total Fecal Coliform Bacteria Testing Coliform Bacterial Test Kits Microorganisms Drinking Water.” Water-Research.Net, 2020, https://water-research.net/index.php/water-testing/bacteria-testing/coliform-bacteria.
“3M Petrifilms – Coliform – E. Coli Plates”. Msu.Edu, 2020, https://msu.edu/course/fsc/441/3mc&ec.html.