Abstract

The strain KK1 isolated from soil contaminated with polycyclic aromatic hydrocarbons was identified as Pseudomonas sp. based on analyses by MIDI and Biolog Identification System. Cellular and physiological responses of strain KK1 to two-ring polycyclic aromatic hydrocarbon, naphthalene were evaluated using radiorespirometry, PLFAs and sequence analysis of Rieske-type iron sulfur center of dioxygenase. KK1 was found to be able to rapidly mineralize naphthalene. Notably, KK1 cells pre-grown on phenanthrene were able to mineralize naphthalene much more rapidly than naphthalene-pregrown cells. The total cellular fatty acids of KK1 were comprised of eleven C-even and two C-odd fatty acids (fatty acids < 0.2% in abundance were not considered in this calculation). Lipids 12:0 2OH, 12:0 3OH, 16:0, 18:1 6c, 18:0 increased for naphthalene-exposed cells, while lipids 18:1 7c/15:0 iso 2OH, 17:0 cyclo, 18:1 7c, 19:0 cyclo decreased. Data from Northern hybridization using a naphthalene dixoygenase gene fragment cloned out from KK1 as a probe provided the information that naphthalene dioxygenase gene was more highly expressed in cells grown on phenanthrene than naphthalene.

• Keywords: naphthalene; PLFA; dioxygenase; Pseudomonas