DEGRADATION OF ALKYLPHENOL ETHOXYLATES BY PSEUDOMONAS SP STRAIN TRO1

An alkylphenol ethoxylate-degrading bacterium was isolated from activa ted sludge of a municipal sewage treatment plant by enrichment culture . This organism was found to belong to the genus Pseudomonas; since no corresponding species was identified, we designated it as Pseudomonas sp. strain TR01. This strain had an optimal temperature and pH of 30 degrees C and 7, respectively, for both growth and the degradation of Triton N-101 (a nonylphenol ethoxylate in which the average number of ethylene oxide [EO] units is 9.5). The strain was unable to mineralize Triton N-101 but was able to degrade its EO chain exclusively. The re sulting dominant intermediate was identified by normal phase high-perf ormance liquid chromatography (HPLC) and gas chromatography-mass spect rometry as a nonylphenol ethoxylate with 2 mol of EO units. A carboxyl ated metabolite, [(nonylphenoxy)ethoxyl acetic acid, was detected by g as chromatography-mass spectrometry. This bacterium also metabolized a lcohol ethoxylates with various numbers of EO units but not polyethyle ne glycols whatever their degree of polymerization. By oxygen consumpt ion assay, the alkyl group or arene corresponding to the hydrophobic p art of alcohol ethoxylates or alkylphenol ethoxylates was shown to con tribute to the induction of the metabolic system of the EO chain of Tr iton N-101, instead of the EO chain itself, which corresponds to its h ydrophilic part. Thus, the isolated pseudomonad bacterium has unique s ubstrate assimilability: it metabolizes the EO chain only when the cha in linked to bulky hydrophobic groups.