title: The optimization and application of two direct viable count methods for bacteria in distributed drinking water.
abstract: The optimal incubation conditions for the direct viable count method with nalidixic acid were determined. They do not differ from those proposed in the literature for a laboratory strain and a mixed bacterial population isolated from drinking water. The direct viable count method with 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) was performed under in situ conditions. The bacteria were incubated with CTC at concentration of 1 mM for 4-6 h at the temperature of the water in the pipes and without the addition of an exogenous substrate. The results obtained for a laboratory strain using the two direct count methods were similar. However, for a mixed bacterial population, the counts were always higher with the CTC method than with the nalidixic acid method.
authors.affiliation: Ecole Polytechnique de Montréal, Department of Civil Engineering, Environment, QC, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Coallier
authors.forename: M
authors.initials: M
authors.lastname: Prévost
authors.forename: A
authors.initials: A
authors.lastname: Rompré
authors.forename: D
authors.initials: D
authors.lastname: Duchesne
mesh_terms: D015169:Colony Count, Microbial / Q000379:methods*; D016972:Enterobacter cloacae / Q000254:growth & development* / Q000302:isolation & purification; D009268:Nalidixic Acid / Q000494:pharmacology; D013778:Tetrazolium Salts; D014871:Water Microbiology
chemical_list: D013778:Tetrazolium Salts; D009268:Nalidixic Acid