| Abstract: | Coliphages may be suitable alternative indicators of fecal pollution in natural waters. The relationship between coliphage and fecal coliform numbers may be expressed by log10 transformed linear regression equations in surface waters (correlation coefficient, r2 = 0.5872; p < 0.001) and in well waters (r2 = 0.4767; p < 0.001). Using the American Public Health Association 919C single agar layer method, coliphages can be enumerated easily and at less cost and more rapidly than coliform enumeration methods. In adapting this test for use in a field test kit, however, further modifications and simplifications are required. The use of 2,3,5-triphenyl tetrazolium chloride (TPTZ) to enhance plaque visibility while helpful, was not essential. Matched-pair t-test analysis showed no significant difference between the plaque numbers enumerated with or without TPTZ to help plaque visibility. The Escherichia coli C host bacteria can be maintained either as a frozen preparation or dried on to paper disks with protective milk colloids. In the latter procedure, a resuscitation period of 18–24 h in broth at 30°C was found to be satisfactory in giving plaque numbers in the test that were not significantly different than when frozen host was used. A portable field kit has been designed to carry out a total of eight tests. The kit includes the media, the bacterial host, petri dishes, syringes, receptacles, and a camping gas cylinder. It measures 38 cm by 25.5 cm by 33.5 cm and weighs about 6.4 kg. Using the kit, the test procedure for a water sample can be carried out in under 15 min. |
