Bacteriology water

Grimes, D.J. (1980). Bacteriological water quality effects of hydraulically dredging contaminated upper Mississippi river bottom sediment. Appl. Environ. Microbiol. 39 782-789. 

Bacteriological sampling is performed by manual techniques because of stringent sterilization requirements. Samples are taken in wide-mouthed, sterile, glass-stoppered bottles that are wrapped in paper prior to sterilization in an autoclave at 138 kPa (20 psi) or in an oven at 170°C. The botde is unwrapped and the lower portion is held in the hand. The sample is taken with the botde mouth in the direction of the flow. The stopper must be protected from contamination, the botde only partially filled, and the sample stored at 4°C after sampling. For bacteriological samples withdrawn from a tap, the water should mn for five minutes and then be shut off the tap should then be sterilized by flaming before a sample is taken. 

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. 

Both multiple-tube and membrane-filter methods are also available for testing for the fecal streptococcal group (20). These assays can be used to provide supplementary data regarding the bacteriological quaUty of water. Other fecal indicators should also be used concurrendy because of the survival characteristics of the fecal streptococci. 

The goal of filtration in the modem municipal treatment plant is a maximum of 0.1 ntu (nephelometric turbidity unit), which ensures a sparkling, clear water (8). Freedom from disease organisms is associated with freedom from turbidity, and complete freedom from taste and odor requites no less than such clarity. The National Interim Primary Drinking Water Regulations (NIPDWR) requite that the maximum contaminant level for turbidity at the point of entry into the distribution system be 1.0 ntu unless it can be shown that levels up to 5 ntu do not interfere with disinfection, interfere with the maintenance of a chlorine residual in the distribution system, nor interfere with bacteriological analyses. 

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. 

Water sample collection techniques differ depending on the source being tested. The minimum number of water samples collected from a distribution system which are examined each month for coliforms is a function of the population. For example, the minimum number required for populations of 1,000 and 100,000 are 2 and 100, respectively. To ascertain compliance with the bacteriological requirements of drinking water standards, a certain number of positive tests must not be exceeded. When 10-ml standard portions are examined, not more than 10 percent in any month should be positive (that is, the upper limit of coliform density is an average of one per 100 ml). 

Water quality must be studied as well as quantity. Chemical and bacteriological examination will indicate the extent of treatment required and will aid in the development of water cost estimates for comparison with other locations. The possible contamination of the water source by other industries in the area should be anticipated. Note that "contamination" may consist of raising the temperature of the water to a level that renders its use as a cooling medium impossible. 

Water analysis for drinking-water supplies is concerned mainly with pollution and bacteriological tests. For industrial supplies a mineral analysis is of more interest. Table 2.11 includes a typical selection and gives some indication of the wide range that can be found. 

Maximum suppressors. Gelatin is widely used as a maximum suppressor in spite of the fact that its aqueous solution deteriorates fairly rapidly, and must therefore be prepared afresh every few days as needed. Usually a 0.2 per cent stock solution is prepared as follows. Allow 0.2 g of pure powdered gelatin (the grade sold for bacteriological work is very satisfactory) to stand in 100 mL of boiled-out distilled water for about 30 minutes with occasional swirling warm the flask containing the mixture to about 70 °C on a water bath for about 15 minutes or until all the solid has dissolved. The solution must not be boiled or heated with a free flame. Stopper the flask firmly. This solution does not usually keep for more than about 48 hours. Its stability may be increased to a few days by adding a few drops of sulphur-free toluene or a small crystal of thymol, but the addition is rarely worth while and is not recommended. 

Doran JW, Linn DM (1979) Bacteriological quality of runoff water from pastureland. Appl Environ Microbiol 37 985-991... 

Blum D, Huttly SRA, Okoro JI et al (1987) The bacteriological quality of traditional water sources in north-eastern Imo State, Nigeria. Epidemiol Infect 99 429 37... 

Robinson, I. and Adams, R.P. (1978) Ultra-violet treatment of contaminated irrigation water and its effect on the bacteriological quality of celery at harvest . Journal of Applied Bacteriology, 45, 83-90. 

Madsen M, Schlundt J (1989) Low-technology water purification by bentonite clay flocculation as performed in Sudanese villages bacteriological examinations. Water Res 23 873-882... 

Bacteriological sulfur, 23 577-578 Bacteriophages, 3 135 12 474 in fermentation, 11 46 Bacteriorhodopsin, 20 826, 840 photochromic material, 6 603 Bacteriosins, 12 76. See also Bacteriocins Bacteriostatic water, 18 714 Bacterium lactis, 11 7 Baculovirus expression system, 5 346 Baddeleyite, 21 489 26 623-624 colorants for ceramics, 7 346t Badische Anilin und Soda Fabrik (BASF) terpenoid manufacture process, 24 481 Baeyer-Villiger oxidation reactions, 14 592 chiral recognition by enzymes, 3 675 microbial, 16 401 Baffled shellside flow, 13 262 Baffles, in stirred tank geometries,... 

Norton CD, LeChevallier MW (2000) A pilot study of bacteriological population changes through potable water treatment and distribution. Appl Environ Microbiol 66(l) 268-276... 

Leclerc H, Mossel DA, Edberg SC et al (2001) Advances in the bacteriology of the coli-form group their suitability as markers of microbial water safety. Annu Rev Microbiol 55 201-234... 

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