ASTM D6734 Low Levels of Coliphages in Water

Scope:

ASTM D6734 can detect coliphages in water with a detection limit of 1 coliphage per volume analyzed. Natural freshwater samples and settled, filtered, or finished water samples can be tested using ASTM D6734. The use of a sensitive host strain in the coliphage test is required to identify coliphages in a water sample. Coliphages were discovered in 6.5 hours using this concentration approach, providing critical information on the sanitary condition of water on the same day. 

Procedure:

In ASTM D6734, a water sample is filtered through a positively charged filter after adjusting to a pH of 6.0 using HCl or NaOH. Trypticase Soy Broth (TSB) at pH 8.5 is used to elute the coliphages caught in the filter. The whole eluate is split into four melted modified nutritional agar (MNA tubes), one for each E. coli C host culture. Each tube’s contents are combined and put into a petri dish. The plates are incubated for 6 hours at 35°C. The coliphages infect the bacteria in the host and produce plaques. The total number of plaques on the four plates corresponds to the number of coliphages in the filtered volume of water.

Video 01: Coliform or E.coli contamination in drinking water

Specimen size:

In the ASTM D6734 test, 5 mL aliquots of the E. coli C culture are used.

Data:

The initial 500 mL water sample filtered yielded 16 PFU (Plaque-Forming Units) per 500 mL of the water sample.

Conclusion:

ASTM D6734 determines coliphages infective for E. coli C in water. The test procedure is easy, affordable, and results in less than 6.5 hours.