Water Lab Report - E.coli (FINAL)

TITLE: IDEXX Colilert®Test Method For The Simultaneous Detection Of Total Coliform and E. Coli In Water OBJECTIVE:  To detect and confirm of total coliform and E. Coli in water. INTRODUCTION: IDEXX Colilert reagent is used around the world for the detection of coliforms and E. coli in water. Colilert is used for the simultaneous detection, specific identification, and confirmation of total coliforms and E. Coli in water. Colilert based on the Defined Substrate Technology®(DSTTM). DST utilizes indicator nutrients which cause target microbes contained in the sample and incubated in the DST reagent system to produce a colour change (or another signal, ie: fluorescence), both indicating and confirming their presence. The indicator-nutrient is cleaved by the target microbe which metabolizes the nutrient and frees the indicator to express a specific color. Total coliform and E. Coli are specifically and simultaneously detected and identified the 1 CFU/100ml of sample, in 24 hours or less, by inoculating the reagent with the water sample and incubating it. APPARATUS:  IDEXX Colilert Reagent  E. Coli  Paddy Water Sample

PROCEDURE: 1. Contents of one pack to a 100ml water sample was added to a sterile vessel. 2. The vessel was cap and shake until dissolved. 3. The reagent mixture was poured into a Quanti tray and sealed in an INDEXX Quanti Tray Sealer. 4. Next, the sealed tray was placed in a 35°C incubator for 24 hours. 5. Then, the result was read according to the result interpretation table. 6. If no yellow color is observed, the test is negative. 7. If the sample has a yellow color equal to or greater than the comparator, the presence of total coliforms is confirmed. 8. The number of positive wells was counted and MPN table provided was referred.

RESULTS: Number of box Group

W1

W2

W3

W4

W5

W6

Type of Bacteria

Large

Small

MPN of Bacteria

Coliform

46

48

533.5

E. coli

30

9

58.8

Coliform

47

47

665.3

E. coli

27

15

60.8

Coliform

48

48

1011.2

E. coli

28

5

47.3

Coliform

47

48

691.0

E. coli

42

39

227.7

Coliform

47

48

691.0

E. coli

47

38

472.1

Coliform

47

48

691.0

E. coli

47

38

472.1

QUESTIONS: MICROBIOLOGICAL ANALYSIS – DETERMINATION OF E. COLI AND TOTAL COLIFORM 1. What is the family name of coliform and E. Coli group?  Coliform bacteria and E. Coli are the type of bacteria that are part of the enterobacteriaceae family.

2. What is the use of UV light? Why that bacteria must be observed under UV light?  The use of UV light is to detect the presence of bacteria. Because bacteria tend to congregate on surfaces where high levels of flavin are present. Flavin is a material that emits a fluorescent glow when exposed to UV light.

3. What to do if water sample has some background color? How to make the dilution?  If there is color, you should examine again with more dilution. Dilute the samples well with PBS of 0.9% NaCl. PBS or 0.9% NaCl is recommendable for the dilution. (If you must use water, apply 0.9 mL or 1.0 mL of sample solution and incubate at 35℃ or 30℃, respectively.)

DISCUSSION: The Colilert-18 system for enumeration of total coliforms and Escherichia coli is approved by the U.S. Environmental Protection Agency for use in drinking water analysis and is also used by various agencies and research studies for enumeration of indicator organisms in fresh and saline waters. Coliform bacteria are widely used as indicators of fecal contamination of both fresh and marine waters. Certain members of the coliform group live outside of the gastrointestinal tract in the environment and may create a false indication of fecal contamination. Index colilert test method is used for the simulteneous detection oftotal coliform and E.Coli in water. From our experiment, MPN of bacteria of coliform in water sample

3 is very higher than other 5 water sample. It is 1011.2. we can see the present of coliform by look at the water sample that turn into yellow flourescent. MPN of bacteria for water sample 1,2, is 533.5, 665.3 while water sample 4,5,6 is in the same value. It is 691.0.For MPN of bacteria for E.coli is very higher in water sample 5 and 6. The value is 472.1. other MPN of bacteria in water sample 1,2,3 and 4 are 58.8, 60.8, 47.3, and 227.7. from this experiment, we can conclude that the water sample that has higher number of MPN of bacteria for E.coli is very polluted.

REFERENCES: 1. Avocet Environmental Testing. Total Coliform Bacteria Testing. Retrieved April 15, 2013, from http://www.avocetlab.com/drinking-water/what-mean/interpreting-results/

2. John Lindquist. (2009). Bacteriology 102. A General Overview of Coliforms. Retrieved April 15, 2013, from http://www.splammo.net/bact102/102coliforms.html

3. Ian L. Pepper, Charles P. Gerba. (2011). Experiment 17: Defined Substrate Technology for Detection of Coliforms and Fecal Coliforms. Environmental Microbiology: A Laboratory Manual

(pp.

129-133).

Academic

Press.

Retrieved

April

15,

2013

from

http://books.google.com.my/books?id=0cFbAoJ_c7UC&pg=PA132&dq=coliform+e.+coli+col ilert+test+experiment&hl=en&sa=X&ei=zK1rUZKmH4HIrQeji4GwAQ&ved=0CC0Q6AEwAA#v =onepage&q=coliform%20e.%20coli%20colilert%20test%20experiment&f=false