Characterization of Sphingomonas isolates from Finnish and Swedish drinking water distribution systems

Sphingomonas species were commonly isolated from biofilms in drinking water distribution systems in Finland (three water meters) and Sweden (five wate r taps in different buildings). The Sphingomonas isolates (n = 38) were cha racterized by chemotaxonomic, physiological and phylogenetic methods. Fifte en isolates were designated to species Sphingomonas aromaticivorans, seven isolates to S. subterranea, two isolates to S. xenophaga and one isolate to S. stygia. Thirteen isolates represented one or more new species of Sphing omonas. Thirty-three isolates out of 38 grew at 5 degreesC on trypticase so y broth agar (TSBA) and may therefore proliferate in the Nordic drinking wa ter pipeline where the temperature typically ranges from 2 to 12 degreesC. Thirty-three isolates out of 38 grew at 37 degreesC on TSBA and 15 isolates also grew on blood agar at 37 degreesC. Considering the potentially pathog enic features of sphingomonas, their presence in drinking water distributio n systems may not be desirable.