Enumeration and phylogenetic analysis of polycyclic aromatic hydrocarbon-degrading marine bacteria from Puget sound sediments.

Naphthalene- and phenanthrene-degrading bacteria in Puget Sound sediments were enumerated by most-probable-number enumeration procedures. Sediments from a creosote-contaminated Environmental Protection Agency Superfund Site (Eagle Harbor) contained from 10(4) to 10(7) polycyclic aromatic hydrocarbon (PAH)-degrading bacteria g (dry weight) of sediment-1, whereas the concentration at an uncontaminated site ranged from 10(3) to 10(4) g of sediment(-1). Isolates of PAH-degrading bacteria were obtained from these most-probable-number tubes as well as from sediment samples from noncontaminated sites and from bioreactors enriched with PAHs. The 18 resulting strains were grouped by whole-cell fatty acid analysis into two subgroups. The larger group of strains belonged to the newly described genus Cycloclasticus, whereas the other group contained members of the genus Vibrio. The Cycloclasticus group seems to be widespread in noncontaminated sediments. PAH degradation was confirmed in selected strains on the basis of removal of phenanthrene from growing cultures.