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Exercise 5 and 6
Overview of Indicator Organisms
17
Biology
Undergraduate 4
03/01/2009

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Term
Coliform
Definition
rod-shaped, gram negative, non-spore forming organisms that ferment lactose w/ production of acid and gas when incubated at 35-37C (citrobacter, enterobacter, escherichia)
Term
Paracolon
Definition
a coliform bacteria which produces acid and gas, but FAILS TO FERMENT LACTOSE in 48 hrs. (salmonella, yersinia)
Term
water quality
Definition
measure of the suitability of water for a specific use base on physical, chemical, and biological parameters
Term
microbial quality of water
Definition
an assessment of the safety of water in respect to the possible transmission of waterborne infectious diseases
Term
Safe drinking water act
Definition
-to protect against giardia, viruses, legionella
-requires that all systems reduce level of giardia by 99.9% and virus by 99.99%
Term
Indicator
Definition
to index potential of pathogens to be there in sufficient numbers when pathogens might possibly be present which could pose as possible risk
Term
An Indicator should:
Definition
1. be absent from non-polluted water
2. present in fecal contaminated waters
3. be greater than enteric pathogen
4. density should be directly correlated w/ degree of fecal pollution
5. have equivalent or greater resistance to disinfectants than enteric pathogens
Term
Total coliform
Definition
all gram-negaive, nonspore-forming, facultative anaerobic bacilli that ferment lactose w/ gas production w/ 48 hrs at 35C
Term
Fecal coliform
Definition
have all characteristics of coliform group, but have the importance of being able to ferment lactose w/ gas production in 24 hrs at 44.5C
Term
MPN method using 5-tube, 3-dilution setup
Definition
accepted technique for fecal enumeration in water that uses A-1 as selective media
Term
Potential Water Quality Indicators
Definition
1. Total coliform
2. Fecal coliform
3. E.coli
4. Enterococci
Term
E.coli as indicator
Definition
1. Lactose broth incubated for 24 hrs at 35C w/ positive result gas prod from fermentation
2. EC medium w/ MUG incubated for 24 hrs for 44C, gas prod is positive for presence of E.coli and fecal contamination
Term
enterococcus
Definition
-survives better in aquatic environment
-salt tolerance up to 6.5% NaCl
-gram +, best for recreational and well-water quality
Term
Problematic indicators
Definition
1. Bacteriophages
2. Salmonella and Shigella
3. Clostridium
4. Coprostanol
Term
Most Probable Number (MPN)
Definition
-do not provide a direct measure of the bacterial count
-statistical approach to estimating the mean density of living orgs present in a given sample that are capable of multiplying in a given liquid medium
-determine total and fecal coliforms levels in water and wastewater
Term
Multiple tube method (MPN method)
Definition
-density of viable microbes is inferred from examining multiple tubes prepared from aliquots of a dilution series and determining the proportions of tubes that are positive for growth
Term
Detection of Positive tubes (multiple tubes)
Definition
-turbidity
-metabolic end-products
-color changes in media
-gas prod
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