ENUMERATION AND PHYLOGENETIC ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBON-DEGRADING MARINE-BACTERIA FROM PUGET-SOUND SEDIMENTS

Naphthalene- and phenanthrene-degrading bacteria in Puget Sound sedime nts were enumerated by most-probable-number enumeration procedures, Se diments from a creosote-contaminated Environmental Protection Agency S uperfund Site (Eagle Harbor) contained from 10(4) to 10(7) polycyclic aromatic hydrocarbon (PAH)-degrading bacteria g (dry weight) of sedime nt(-1), whereas the concentration at an uncontaminated site ranged fro m 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 s ediment samples from noncontaminated sites and from bioreactors enrich ed with PAHs, The 18 resulting strains were grouped by whole-cell fatt y acid analysis into two subgroups. The larger group of strains belong ed to the newly described genus Cycloclasticus, whereas the other grou p contained members of the genus Vibrio. The Cycloclasticus group seem s to be widespread in noncontaminated sediments, PAH degradation was c onfirmed in selected strains on the basis of removal of phenanthrene f rom growing cultures.