Microbiology of Water Flashcards
Pathogenic intestinal infections (BC kaon ug TaPa)
- Bacillary dysentery
- Cholera
- Typhoid Fever
- Paratyphoid Fever
Waterborne enteric bacterial pathogens (Sige’g Swim C Vibrio)
- Shigella dysentery
- Salmonella typhi
- Campylobacter jejuni
- Vibrio cholerae
Why is water microbiology not a reliable indicator of fecal pollution in tropic and subtropic areas?
Soil may naturally contain high levels of E coli.
3 tests for qualitative analysis of water
- Presumptive Test
- Confirmatory Test
- Completed Test
This test is specific for the detection of coliform
Presumptive Test
A specialized broth utilized under Presumptive Test
Lactose Fermentation Broth
This tube is placed in a broth to detect deterioration of the broth before inoculation and identify denitrification by organisms that produce gas by alternate pathways.
Durham Tube
Water is examined to detect this bacterium that indicates fecal pollution.
Escherichia coli
These bacteria are indicators of fecal contamination
Coliform bacteria
Ferments lactose with the production of acid and gas
gram-negative, non-spore-forming bacilli
This medium facilitates the detection of coliform bacteria because these bacteria are capable of using lactose as a carbon source.
Lactose fermentation broth
This tube is utilized for gas collection
Durham tube
Under presumptive test, tubes of the lactose medium are to be inoculated with how many aliquots of water sample? How many tubes are specified in each group?
10 mL, 1 mL, and 0.1 mL;
5 Tubes
The greater the number of tubes per group, the greater the _____________ of the test.
sensitivity
The presence of coliform bacteria is evidenced in its development
gas
This test enables microbiologists to obtain some idea of the number of coliform organisms present.
Most Probable Number (MPN) Test
The presence of a positive or doubtful presumptive test suggests that the water sample is …
nonpotable
Selective and differential media for confirmed test
Eosin-methylene blue (EMB)
Endo Agar
This media inhibits the growth of gram-positive organisms because of its dye.
Eosin methylene blue
(Dye: methylene blue)
In the presence of an acid environment, EMB forms a complex that precipitates out onto the coliform colonies, producing 2 appearances.
- Dark centers
- Green metallic sheen
The reaction is characteristic for E coli.
Dye contained in the Endo agar responsible for the formation of a dark pink complex that turns E coli. colonies and the surrounding medium into pink.
Fuchsin
The EMB agar plate from a positive tube is incubated for and at …
For 24 hours; at 37 oC
Indicates positive completed test
Gram-negative short bacilli
The final analysis of the water sample used to examine the coliform colonies that appeared on the EMB or Endo agar plates.
completed test
This agency has the government mandate to protect the nation’s waterways and terrestrial environments from human contamination or damage.
Environmental Protection Agency (EPA)
The absence of E. coli indicates
negative test- water is not contaminated with fecal wastes and is therefore potable
Used in quantitative analysis for the purpose of counting the total coliforms, fecal coliforms, and E coli.
Most Probable Number (MPN)
Advantages of MPN
- Inoculated greater amounts of sample
- Has higher sensitivity than plate count method
- Versatile
Presumptive test for coliform under quantitative analysis utilizes
Lauryl Sulphate Tryptose (LST)
The LST is incubated at and for …
At 35 oC; for 24 hours
Selective medium for quantitative analysis
Brilliant Green Broth (BGB)
A medium that inhibits noncoliforms with the presence of lactose and 2% bile
Brilliant Green Broth
Growth is verified by
turbidity or cloudiness
Indicates gas production
bubbles in Durham tube
The membrane filters are capable of retaining organisms larger than …
larger than 0.45 um
Trapped microoganisms are transferred in 50-mm petri dish containing …
adsorbent pad
Agar medium used for Membrane Filter Method
Endo Agar
In the endo agar, coliform growth has this appearance
Red or Metallic colonies
Formula for total colony count
Total Colony Count = colony count x DF/ mL of sample used multiplied by 100
Presumptively identifies Enterobacteriaceae and verotoxin producing E. coli
4-Methylumbelliferyl-B-d-glucuronide (MUG) Test
Principle for MUG Test
B-d-glucopyranosid-uronic with the enzyme B-d-glucuronidase is separated into Alycons and D-glucuronic acid + 4-methylumbelliferyl-B-d-glucuronide would yield 4-methylumbelliferyl moiety = Blue Fluorescence
MUG test is observed in
366-nm UV
Differentiates microoganisms based on metabolic reaction in litmus milk
litmus milk medium
What are observed in the litmus milk medium?
- Fermentation
- Clot formation
- Digestion
- Formation of gas
Appearance of Indicator Litmus Dye when ph change to acid
Pink, mauve [Record: Acid (A)]
Appearance of Indicator Litmus Dye when pH change to Alkaline
Blue [Record: Alkaline (K)]
Appearance of Indicator Litmus Dye when pH has no change
Purple
Appearance of Indicator Litmus Dye when pH change to independent as a result of reduction of the indicator
white [Record: Decolorized]
Consistency of milk when pH is acid or alkaline
Coagulation or clot
Consistency of milk when pH is acid
Dissolution of clot with clear, grayish, watery fluid, and a shrunken, insoluble pink clot
[Record: Digestion]
Consistency of milk when pH is alkaline
Dissolution of clot with grayish, watery fluid and a clear, shrunken, insoluble blue clot
[Record: Peptonization]
