water microbiology.ppt for undergraduate

water microbiology.ppt for undergraduate

1. V. Microbiology of waterV. Microbiology of water
A. Waterborne microbial pathogensA. Waterborne microbial pathogens
B. Indicator bacteria for drinking waterB. Indicator bacteria for drinking water
C. Other indicators for drinking and C. Other indicators for drinking and
recreational waterrecreational water

2. A.WA.Waterborne microbial pathogensaterborne microbial pathogens
Microbiology review:Microbiology review:
Microbes in water Microbes in water
include:include:
–BacteriaBacteria
–Virus Virus
–ProtozoaProtozoa
A few microbes (A few microbes (pathogenspathogens) )
are capable of causing are capable of causing
disease, and may be disease, and may be
transmitted by water.transmitted by water.

3. Waterborne pathogens:Waterborne pathogens:

Some common pathogens:Some common pathogens:
Salmonella typhiSalmonella typhi
Escherichia coli Escherichia coli

Vibrio choleraVibrio cholera
Pseudomonas aeruginosa Pseudomonas aeruginosa
ShigellaShigella spp. spp.
CryptosporidiumCryptosporidium

Giardia lambliaGiardia lamblia
NorwalkvirusNorwalkvirus

4. Cryptosporidum and
cryptosporidiosis
Cryptosporidium parvumCrypto “Oocysts

5. Giardia lamblia
(giardiasis)
Original image by Arturo Gonzalez, CINVESTAV, Mexico. Used with permission of Javier Ambrosio,
UNAM, Mexico

6. Giardia lamblia

Giardia lambliaGiardia lamblia
trophozoites live in the trophozoites live in the
small intestine of the small intestine of the
host.host.
The trophozoites The trophozoites
average about 15 µm in average about 15 µm in
length, have a distinct length, have a distinct
"tear-drop" shape and "tear-drop" shape and
two nuclei at the anterior two nuclei at the anterior
end end
Giardia lamblia troph.
  The two nuclei are easy to see in this image.  (Original image from a Japanese
language site tentatively titled "Internet Atlas of Human Parasitology."

8. B. Indicator bacteria for B. Indicator bacteria for
Drinking Water:Drinking Water:

Indicator microorganisms Indicator microorganisms are used to are used to
indicate an increased risk of pathogen indicate an increased risk of pathogen
contamination due to fecal contamination.contamination due to fecal contamination.

Indicator microbes should be:Indicator microbes should be:
–Always present when feces/sewage is presentAlways present when feces/sewage is present
–Always absent when feces/sewage is absentAlways absent when feces/sewage is absent
–Survives longer in water than any of the Survives longer in water than any of the
pathogenic speciespathogenic species
–Easily isolated and identified.Easily isolated and identified.

9. Indicator bacteria:Indicator bacteria:

ColiformColiform bacteria ( bacteria (E. coliE. coli-like) are the -like) are the
most often used indicator bacteria for most often used indicator bacteria for
water quality assessment in the U.S.water quality assessment in the U.S.

10. Characteristics of coliforms:Characteristics of coliforms:

Aerobic or facultative,Aerobic or facultative,

Gram-negative,Gram-negative,

Non-spore forming,Non-spore forming,

Bacilli, Bacilli,

which ferment which ferment
lactose to form acid lactose to form acid
and/or gas within and/or gas within
48 hours at 35 48 hours at 35
oo
C.C.

11. More specific coliforms:More specific coliforms:

Coliforms are often found naturally Coliforms are often found naturally
in soil, water, plants, etc.in soil, water, plants, etc.

Fecal coliforms Fecal coliforms are a more specific are a more specific
coliforms that usually come from coliforms that usually come from
feces.feces.

E. coli E. coli is the most is the most
specific indicatorspecific indicator

12. Guidelines and methods for Guidelines and methods for
enumerating coliforms:enumerating coliforms:

EPA guidelines for coliforms in EPA guidelines for coliforms in
drinking water are < 1 CFU/100 drinking water are < 1 CFU/100
ml.ml.
Tests used to isolate and Tests used to isolate and
enumerate coliforms in water enumerate coliforms in water
include:include:
–m-Endo media m-Endo media
–m-FC media m-FC media
–MUG mediaMUG media

13. C. Other indicators for drinking and C. Other indicators for drinking and
recreational waterrecreational water

Limitation of Limitation of Total coliformTotal coliform as as
drinking water microbial drinking water microbial
indicatorindicator
–Ubiquitous.Ubiquitous.
–Less resistant to traditional Less resistant to traditional
disinfection.disinfection.
–Proliferate in the biofilms of Proliferate in the biofilms of
water distribution systemswater distribution systems

14. 
Limitation of Limitation of Fecal coliformsFecal coliforms
–Klebsiella pneumoniaeKlebsiella pneumoniae
–Less resistant to traditional disinfection.Less resistant to traditional disinfection.

Limitation of Limitation of E. coliE. coli
–Less resistant to traditional disinfection.Less resistant to traditional disinfection.

15. Microbial Indicators for Microbial Indicators for
Recreational WaterRecreational Water

Total coliform?Total coliform?

Fecal coliform?Fecal coliform?
–Average 200 MPN/100 mlAverage 200 MPN/100 ml

E. Coli (fresh water)?E. Coli (fresh water)?
–Average 126 MPN/100 ml.Average 126 MPN/100 ml.

Enterococci (salt Enterococci (salt
water)water)
–Average 35 MPN/100 ml.Average 35 MPN/100 ml.