Robust explanations of a coliform test: what a positive result from local river

Question

Robust explanations of a coliform test: what a positive result from local river water samples mean. (Not all coliforms are pathogens right?) and what they imply about the environment at large?

Robust explanations of a enrichment assay: what would a postive and negative result look like? (for dextrose, sitrose, glucose, and formate), and what they imply about the environment at large?

Robust explanation of a resazurin assay: what does a postive and a negative result of a river water mean? and what does it imply about the enviroment at large?

Explanation / Answer

1.Coliforms come from the same sources as pathogenic organisms. Coliforms are relatively easy to identify, are usually present in larger numbers than more dangerous pathogens, and respond to the environment, wastewater treatment, and water treatment similarly to many pathogens. As a result, testing for coliform bacteria can be a reasonable indication of whether other pathogenic bacteria are present.

The most basic test for bacterial contamination of a water supply is the test for total coliform bacteria. Total coliform counts give a general indication of the sanitary condition of a water supply.

Total coliforms include bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste.
Fecal coliforms are the group of the total coliforms that are considered to be present specifically in the gut and feces of warm-blooded animals. Because the origins of fecal coliforms are more specific than the origins of the more general total coliform group of bacteria, fecal coliforms are considered a more accurate indication of animal or human waste than the total coliforms.
Escherichia coli (E. coli) is the major species in the fecal coliform group. Of the five general groups of bacteria that comprise the total coliforms, only E. coli is generally not found growing and reproducing in the environment. Consequently, E. coli is considered to be the species of coliform bacteria that is the best indicator of fecal pollution and the possible presence of pathogens.Most coliform bacteria do not cause disease. However, some rare strains of E. coli, particularly the strain 0157:H7, can cause serious illness. Recent outbreaks of disease caused by E. coli 0157:H7 have generated much public concern about this organism
If coliform bacteria are present in your drinking water, your risk of contracting a water-borne illness is increased. Although total coliforms can come from sources other than fecal matter, a positive total coliform sample should be considered an indication of pollution in your well. Positive fecal coliform results, especially positive E. Coli results, should be considered indication of fecal pollution in your well.

2.This method tests for the presence of free carbonyl group (C=O), the so-called reducing sugars. This involves the oxidation of the aldehyde functional group present in, for example, glucose and the ketone functional group in fructose

Although this is a convenient and relatively inexpensive method, due to the relatively low specificity, one must run blanks diligently if the colorimetric results are to be interpreted correctly and accurately. One can determine the background absorption on the original cellulose substrate solution by adding cellulase, immediately stopping the reaction, and measuring the absorbance, i.e. following exactly the same procedures for the actual samples. When the effects of extraneous compounds are not known, one can effectively include a so-called internal standard by first fully developing the color for the unknown sample; then, a known amount of sugar is added to this sample. The increase in the absorbance upon the second color development is equi

3.Resazurin based assays show excellent correlation to reference viability assays such as formazan-based assays (MTT/XTT) and tritiated thymidine based techniques, while being much easier and safer to use for the use Besides standard applications as cell culture assays (cell counting, cell proliferation assays and cytotoxicity testing, it also can be multiplexed with several chemiluminescent assays, such as cytokine assays, caspase assays to measure apoptosis, or reporter assays to measure a gene or a protein expression. The irreversible reaction of resazurin to resorufin is proportional to aerobic respiration

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