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V. Microbiology of water

V. Microbiology of water. A. Waterborne microbial pathogens B. Indicator bacteria for drinking water C. Other indicators for drinking and recreational water. A.W aterborne microbial pathogens Microbiology review:. Microbes in water include: Bacteria Virus Protozoa

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V. Microbiology of water

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

  2. A.Waterborne microbial pathogensMicrobiology review: • Microbes in water include: • Bacteria • Virus • Protozoa • A few microbes (pathogens) are capable of causing disease, and may be transmitted by water.

  3. Waterborne pathogens: • Some common pathogens: • Salmonella typhi • Escherichia coli • Vibrio cholera • Pseudomonas aeruginosa • Shigella spp. • Cryptosporidium • Giardia lamblia • Norwalkvirus

  4. Cryptosporidum and cryptosporidiosis Crypto “Oocysts Cryptosporidium parvum

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

  6. Giardia lamblia • Giardia lamblia trophozoites live in the small intestine of the host. • The trophozoites average about 15 µm in length, have a distinct "tear-drop" shape and two nuclei at the anterior 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."

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

  8. Indicator bacteria: • Coliform bacteria (E. coli-like) are the most often used indicator bacteria for water quality assessment in the U.S.

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

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

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

  12. C. Other indicators for drinking and recreational water • Limitation of Total coliform as drinking water microbial indicator • Ubiquitous. • Less resistant to traditional disinfection. • Proliferate in the biofilms of water distribution systems

  13. Limitation of Fecal coliforms • Klebsiella pneumoniae • Less resistant to traditional disinfection. • Limitation of E. coli • Less resistant to traditional disinfection.

  14. Microbial Indicators for Recreational Water • Total coliform? • Fecal coliform? • Average 200 MPN/100 ml • E. Coli (fresh water)? • Average 126 MPN/100 ml. • Enterococci (salt water) • Average 35 MPN/100 ml.

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