Newly isolated polyethylene glycol (PEG) 4,000 and 20,000-utilizing bacteria K1 and N6 were chemically characterized as Sphingomonas sp. 16S-rRNA sequencing and DNA/DNA homology of the two strains and related organisms showed that they had a high degree of similarity with S. macrogoltabidus (previously identified as a PEG 4,000-utilizing bacterium), but K1 and N6 both showed very low similarity with S. terrae (another PEG 20,000-utilizing Sphingomonas species). The two strains were unlike each other as regards their utilization of different PEG molecular species and the productivity of viscous materials attached to cells.