Comparison of methods for detecting genotypes of F-specific RNA bacteriophages and fingerprinting the origin of faecal pollution in water samples

The performance of Salmonella typhimurium WG49 and Escherichia coli HS(pFam p)R was compared on detecting the different genotypes of F-specific RNA bac teriophages by plaque hybridisation. The sensitivity of this assay was also compared with the sensitivity of RT-PCR followed by Southern blotting for detecting F-specific RNA bacteriophages belonging to genotype III in water. S. typhimurium WG49 detected slightly higher numbers of F-specific RNA bac teriophages than E. coli HS(pFamp)R both in mixtures of pure culture bacter iophage suspensions and in water samples. There were no differences between the two host strains with regard to detection of the four genotypes of F-s pecific RNA phages both in mixtures of pure culture bacteriophage suspensio ns and in environmental samples. In urban sewage samples, the host strains detected genotypes II and III as the predominant F-RNA bacteriophages. Plaq ue transfer to a N+ hybond membrane and posterior hybridisation was easier using S. thyphimurium WG49 as the host strain. The efficiency of detection in sewage of genotype III F-specific RNA bacteriophages by RT-PCR was infer ior to that of plaque hybridisation with the assay conditions described bel ow. Hybridisation of plaques obtained on WG49 seems to be the most sensitiv e method to study the distribution of genotypes of F-specific RNA bacteriop hages in water samples. (C) 2000 Elsevier Science B.V. All rights reserved.