Incidence of coliphage in potable water supplies.

Samples of drinking water from different sources in greater Cairo, Egypt, and bottled drinking water were tested for total coliform, fecal coliform, and coliphage populations. Of the 147 samples tested, 4 samples were positive for both total coliforms and coliphage, 65 samples were negative for total coliforms, fecal coliforms, and coliphage, and 78 samples were positive for coliphage and negative for total coliforms and fecal coliforms. The incidence of coliphage in these potable water supplies reflects the probability of human pathogenic virus survival in these waters also.

Bacterial food-poisoning versus coliforms-faecal streptococci and gamma radiation survival/dose.

All the species tested were sensitive to gamma radiation treatment, even at a dose as low as 0.001 Mrad. The spore-former Bacillus cereus (PCJ 213) proved to be more resistant than the rest of the tested species, while the Gram-negative organisms were more susceptible to irradiation treatment. The tolerance among those organisms is depicted by the descending order: Proteus vulgaris, irregular VI, Escherichia coli I, E. coli III, and Salmonella typhi-murium. Yet all the tested faecal streptococci species, with the exception of Streptococcus bovis, may be regarded as holding an intermediate position between the more resistant B. cereus (PCJ 213) and the more sensitive Gram-negative organisms.

Bacteriophages recovery from raw sewage of different texture.

Bacteriophages recovery was enhanced by the addition of Mg2+ divalent cation or when the raw sewage filtrate was adjusted to pH 4.5. On the other hand, when Mg2+ or Ca2+ divalent cations were added to the acidified sewage filtrate, all sensitive phase species were found to be phage-resistant.

Direct MPN for faecal coliform.

Samples of Nile and Ismailia canal water were subjected to direct inoculation and incubation at elevated temperatures. The results obtained showed that the use of MacConkey broth medium was better than EC broth. In addition, the Direct MPN technique revealed to be suitable and superior by 90% of the examined samples. A total of 300 isolates was recovered from Direct MPN-technique and identified by using IMViC reactions plus Eijkman test. 96% of the isolates were E. coli proper and 4% irregular types.

On the transformation of coliform types, proper and irregular forms.

Physiological changes have been induced in strains of E. coli I and its irregular forms, using a basal synthetic medium and addition of sodium pyruvate, or glucose, or yeast extract, or peptone. Changes in biochemical patterns, using the IMViC reactions plus growth at 44.5 degrees C, were induced, thus brining transformations between the regular types and irregular forms. Ultra-violet irradiation of E. coli I for 90 seconds may turn it into a methyl-red negative strain, while education of E. coli III for producing acid and gas at 44.5 degrees C was possible. Thus, E. coli I could be transformed to give the same reactions as the untyped form 1 of Geldreich (1966) through U.V. irradiation, while E. coli III may give the biochemical reactions of E. coli I via heat-resistance and training in MacConkey broth. The relationship between regular and irregular coliforms was also verified by phage typing. The results obtained were discussed both qualitatively, using "lytic activity", and quantitatively in terms of "efficiency of plating", especially with sewage-derived phages and irregular coliforms.