Resources Microbiological testing Every aspect of the world — including humans, animals and plants — contains bacteria. Bacteria serve a critical role in ecology of our planet and the day-to-day activities of our lives. Other, much rarer types of bacteria can be harmful to health.
Water - Microbiological Analysis of Water Key Points - Waterborne pathogens are a leading cause of disease and death worldwide - Routine microbiological testing of drinking water supplies, recreational waters and environmental waters is essential for the protection of public health - Microbiological water testing is based on the detection of indicators of faecal contamination rather than specific pathogens - Most routine laboratory methods are now based on membrane filtration According to the World Health Organisation WHO more than 3.
That makes infections contracted from contaminated water supplies a leading cause of illness and death worldwide and helps to explain why the provision of safe drinking water is such a high priority for governments and aid agencies. The great majority of waterborne infections are the result of faecal contamination, either from humans or animals, and preventing sewage and agricultural effluent from entering water supplies is the key to safe drinking water.
The infrastructure and treatment procedures needed to provide safe water supplies are well understood and have been part of life in most developed countries for so long that safe drinking water is often taken for granted.
But maintaining an uncontaminated water supply requires constant attention and regular monitoring by a programme of testing.
The most effective way to check water supplies for faecal contamination remains microbiological analysis and a range of test methods designed for that purpose has been developed for the water industry. Testing is important not just for drinking water supplies, but also for recreational and environmental waters where human contact with contaminated water could occur.
Microbiological water testing Rationale A large range of pathogenic microorganisms could be present in contaminated water and some of the more important water-borne pathogens are listed below.
Bacteria Aeromonas spp, Campylobacter spp, Clostridium spp. Testing for all these pathogens directly is not practical, partly because of the difficulty and expense of conducting such comprehensive testing on large numbers of water samples, but also because pathogens tend to be present only in low numbers even in heavily contaminated water.
Indicator organisms Indicator organisms are bacterial species that are present in high numbers in human and animal faeces and are also present in sewage effluent. Ideally they should not originate from other sources, should not be able to multiply in water supplies or aquatic environments and should be relatively simple to isolate from water samples.
Unfortunately, no one organism completely meets all these requirements, but it is E. Other members of the coliform group, such as Klebsiella spp. Other species that are present in faeces in lower numbers may also be used as indicator organisms, notably enterococci and to a lesser extent Clostridium perfringens.
The basic framework of microbiological testing of drinking water supplies, treated and untreated recreational waters and environmental waters is built on the detection of these indicator organisms and decades of use has demonstrated the effectiveness of this approach in maintaining safe water supplies.
Tests for total coliforms and faecal coliforms coliform species able to grow at 44oC are used routinely to screen samples for faecal indicator species. However, it should be noted that the absence of indicators does not guarantee the absence of pathogens any more than their presence can be taken to mean that pathogens are necessarily present.
Neither pathogens nor indicator organisms can survive indefinitely in water, especially in environments subject to chlorination or high levels of ultra-violet radiation.
There are some situations where it is necessary to test directly for water borne pathogens. For example, public drinking water supplies are routinely monitored for the presence of the protozoan parasite Cryptosporidium, which has caused water borne disease outbreaks in many developed countries.
Testing for Cryptosporidium in water samples is a specialised operation and is not considered further here. The same applies to detection of Legionella spp. However, testing for Pseudomonas aeruginosa, especially in treated recreational waters, such as swimming pools, is included below.
Water quality parameters In addition to tests for indicator organisms and certain specific pathogens, non-selective colony counts are also routinely carried out to determine the population of heterotrophic bacteria present. Counts at two temperatures 22oC and 37oC are typically performed to provide information on the general microbiological population of the water and detect sudden changes in water quality.
Counts at 37oC have been used to indicate faecal contamination in the past, but this is not generally considered to be reliable. Sampling Obtaining representative water samples is a critical part of microbiological water analysis.
Samples should be collected in sterile containers, which for chlorinated water should contain an appropriate quantity of sodium thiosulphate to neutralise residual chlorine. It is also important to ensure that the sampler does not contaminate the inside of the sample container and rubber gloves should be worn where necessary.
Ideally water from piped distribution systems or tanks should be taken from hygienically designed sample taps. Bacterial growth may occur in taps and it is good practice to disinfect the tap with alcohol or another suitable disinfectant before sampling.
Water should be allowed to run through the tap for several minutes to flush out any contamination within the tap and ensure that the sample is representative. The samples should be tested as soon as possible after collection.
There are many considerations to be borne in mind when sampling water and these vary with the type of sample being taken and the location. Staff required to take water samples for microbiological analysis should be trained according to the principles outlined in such publications.
The idea of establishing a professional body of Science Technologists to manage and maintain institutional and industrial laboratories in Nigeria was proposed in July by the then Federal Commissioner of Education late Mr.
A. Y. Eke.
Abstract. The formation of deposits on heat transfer surfaces is an important problem during convective and nucleate boiling heat transfer to water. Journal of Microbiological Methods 49 () 31–54 be an interesting viable alternative to the conventional culture methods for the detection of coliforms in drinking water, as it provides quantitative data in a fairly short period of time (6 to .
Sep 30, · Thesis On Microbiological Analysis Of Water. Thesis On Microbiological Analysis Of Water – Simino Electric thesis on microbiological analysis of water of, analysis, water, on, thesis, microbiological.
The water activity, moisture sorption isotherm, and solubility of trehalose were determined. The water activity of a saturated solution of trehalose, as measured by an electric hygrometer, was and at 20 and 25°C, respectively.