RAPID COMMUNICATION DEGRADATION OF DIBENZOFURAN BY PSEUDOMONAS PUTIDA PH-01 HYO BONG HONG 1 , YOON SEOK CHANG 1 *, SUNG DEUK CHOI 1 and YONG HA PARK 2 1 School of Environmental Engineering, Pohang University of Science and Technology, Hyojadong, Namku, Pohang, 790-784, South Korea and 2 Korea Research Institute of Bioscience and Biotechnology, Taejon, 305-333, South Korea (First received 13 October 1999; accepted in revised form 22 December 1999) AbstractÐThe ability of a Pseudomonas putida PH-01 to degrade the dioxin-like compound dibenzofuran was characterized and the eect of extracellular substance produced during the incubation was determined. The strain grew aerobically on dibenzofuran as the sole source of carbon and energy, and the solubility of dibenzofuran was rapidly increased with the appearance of those extracellular substances. During the incubation, production of salicylic acid, catechol, gentisic acid, and other unidenti®ed trace metabolic products was observed. After six days of incubation, catechol accumulated mainly in the culture medium. 7 2000 Elsevier Science Ltd. All rights reserved Key wordsÐdibenzofuran, degradation, Pseudomonas putida INTRODUCTION Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are becom- ing omnipresent environmental pollutants in some parts of the world through the synthesis of haloaro- matic compounds, or by their thermal destruction in incineration processes. Although a non-haloge- nated dibenzofuran (DF) has a lower toxicity than halogenated forms, aerobic biodegradation of non- halogenated or slightly halogenated dibenzofurans (DFs) and dibenzo-p-dioxins (DDs) could be im- portant in the ®nal treatment of heavily haloge- nated DFs and DDs (Hammer et al., 1998). Consequently, many eorts have been made to reduce the emission and remove these chemicals from the environment. Recently, some bacterial strains which are able to metabolize dibenzofuran were isolated and, in most cases, the ring cleavage reactions have been elucidated (Halden and Dwyer, 1997; Wittich, 1999). Brevibacterium sp. strain DPO1361 and Sphingomonas sp. strain HH69, able to degrade DF, were isolated by Strubel et al. (1991) and Harms et al. (1995). Elucidation of the DF degrative pathways of Pseudomonas sp. strain HH69, Sphingomonas strain RW1, and Terrabacter sp. strain DPO360 revealed a new type of oxidative attack, at an angular position on the two carbon atoms adjacent to the ether bridge (Fortnagel et al., 1990; Happe et al., 1993; Patricia and Cook, 1993; Resnick and Gibson, 1996; Schmid et al., 1997). From the degradation of DF, an unstable hemiace- tal was formed, which was spontaneously trans- formed to 2,2 ',3-trihydroxybiphenyl. In this way, the single enzymatic reaction facilitates both acti- vation of the aromatic ring and ®ssion of the ether linkage (Resnick and Gibson, 1996). The hydroxyl- ated aromatic rings of the trihydroxy intermediates were then meta-cleaved (Strubel et al., 1991). This reaction was termed angular dioxygenation (Wit- tich, 1999). Several hydroxylated, methoxylated, acetoxylated, and nitrated DFs were converted by the enzyme system of strain HH69 to the corre- sponding salicylates. The use of Staphylococcus aur- iculans for DF degradation was characterized by the work of Monna et al. (1993). This strain attacks DF and other related compounds but does not grow on them. In addition to the microbial strains described above, some other Pseudomonas strains are known to metabolize DF as carbon source (Fortnagel et al., 1990; Resnick and Gibson, 1996). However, even though Pseudomonas putida consti- tutes the majority of these Pseudomonas strains, the catabolic degradation of biaryl ether like dibenzo- furan has never been reported. Wat. Res. Vol. 34, No. 8, pp. 2404±2407, 2000 7 2000 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0043-1354/00/$ - see front matter 2404 www.elsevier.com/locate/watres PII: S0043-1354(00)00122-6 *Author to whom all correspondence should be addressed.