Coliforms

The characteristic features of the coliforms are non-sporing, Gram-negative rods, which are bile tolerant and able to ferment lactose at 37 °C producing acid and gas within 48 hours. The term faecal coliform was used to describe coliforms capable of fermenting lactose to acid and gas within 24 hours at 44 °C. The term thermotolerant coliforms is now used more commonly in the UK, although the term faecal coliform is still widely used elsewhere. It should be pointed out that not all thermotolerant coliforms are faecal in origin. 

The presence of coliforms in water indicates that pathogens could be present, and that the supply is potentially dangerous, although there is no correlation between numbers of coliforms and pathogens. The absence of coliforms indicates that pathogens are probably absent. 

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Membrane filter showing colonies of coliform bacteria. The number of colonies are counted and reported as colonies/100 ml of sample. 

N -acetyl-L-omithiae) Baracolohactrum coliforme B. suhtilis Streptomjces virginae arg , uracil Arghydroxamate lys 11... 

A bacteriological examination of water is primarily carried out to determine the possible presence of harmful microorganisms. Testing is actually done to detect relatively harmless bacteria called colon bacilli commonly called the coliform group, which are present in the intestinal tract of humans and animals. If these organisms are present in a water in sufficient number, then this is taken to be evidence that other harmful pathogenic bacteria may also be present. 

One standard test used to determine the presence of the coliform group is called the multiple-tube fermentation technique (sometimes called the presumptive test). If this test indicates the presence of these bacteria, then a confirmed test must be done. If only negative colonies or no colonies develop during this test, it is considered negative otherwise, a completed test must be undertaken. Positive results obtained in the completed test are evidence for the presence of coliform bacteria. Testing methods have been given by the APHA, and the detailed procedures contained therein should be consulted (20). 

Another standard test, which is much simpler and more convenient, is the membrane filter technique. A suitable volume of sample is filtered through a sterile, 0.45-p.m membrane filter. The filter is placed in a petri dish containing a specific growth medium (M-Endo nutrient broth, M-Endo medium) and incubated for 24 h at 35°C. If after this time the colonies show the characteristic green sheen, this is taken as positive evidence for the presence of the coliform group (see Water, sewage). 

Fecal Goliforms. Eecal coliforms are those originating from the intestines of warm-blooded animals. Eecal coliforms can be deterrnined by a multiple-tube procedure, which must be appHed to a positive presumptive test for optimum recovery of fecal coliforms (20). Incubation must be at 44.5 0.2°C for 24 2 h. Gas production during incubation is positive evidence of fecal coliform poUution. 

A membrane filter technique can also be used to determine the presence of fecal coliforms, and this procedure is said to be 93% accurate (20). A sample is passed through a membrane filter, and this filter is placed in a petri dish containing an enriched lactose medium. The dishes are incubated at... 

Specifications. Typical specifications are indicated in Table 7 for Hquid, frozen, and dried egg products. Every lot of egg product is tested for moisture, pH, total bacteria count, coliform, yeast and mold, and Salmonella. 

Includes 10 gm maximum each of yeast, mold, and coliform all products must be Salmonellae negative. 

Product specifications for microbial food enzymes have been estabUshed by JECEA and ECC. They limit or prescribe the absence of certain ubiquitous contaminants such as arsenic, heavy metals, lead, coliforms, E. coli and Salmonella. Furthermore, they prescribe the absence of antibacterial activity and, for fungal enzymes only, mycotoxins. 

Total Conforms (including fecal coliform and E. Coll) 0 5.0% Used as an indicator that other potentially harmful bacteria may be present Coliforms are naturally present in the environment fecal coliforms and E. coli come from human and animal fecal waste. 

No more than 5.0% samples total coliform-positive in a month, (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive). Every sample that has total coliforms must be analyzed for fecal coliforms. There may not be any fecal coliforms or E. coli. Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Disease-causing microbes (pathogens) in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms. These pathogens may pose a special health risk for infants, young children, and people with severely compromised immune systems. 

Study has proved that these coliform bacteria indicate the presence of human or animal wastes in water. Coliform bacteria naturally exist in the intestines of humans and certain animals. Thus, the presence of these bacteria in water is accepted proof that the water has been contaminated by human or animal wastes. Although such water may contain no pathogens, an infected person, animal or a carrier of disease, could add pathogens at any moment Thus, immediate corrective action must be taken. The presence of coliform bacteria shows water is contaminated by human... 

What are coliforms and how are they introduced inot water supplies ... 

The current concept of disinfection is that the treatment must destroy or inactivate viruses as well as bacillary pathogens. Under this concept, the use of coliform counting as an indicator of the effectiveness of disinfection is open to severe criticism given that coliform organisms are easier to destroy than viruses by several orders of magnitude. 

A fairly low dose of ultraviolet light can kill 99 percent of the fecal coliform and fecal streptococcus. 

The UV dose required to reduce the survival fraction of total coliform and fecal streptococcus to 102 (99 percent removal) is approximately 4 x 10 ff Einsteins/ml. 

Bacteria are named according to a binomial system. The first word is the genus and the second is the species name. The most frequently referred to bacterium in the sanitary field is Escherichia coli. E. coli is a common coliform that can be used as an indicator of water s bacteriological quality. Under a microscope and magnified 1,000 times, cells appear as individual short rods. 

Coliform criteria for body-contact water use and recreational use have been established by most states. Upper limits of 200 fecal coliforms per 100 ml and 2,000 total coliforms per 100 ml have been established. These values are only... 

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