Degradation of 4-Fluorobiphenyl by Mycorrhizal Fungi as Determined by ¹⁹ F Nuclear Magnetic Resonance Spectroscopy and ¹⁴ C Radiolabelling Analysis

Abstract

The pathways of biotransformation of 4-fluorobiphenyl (4FBP) by the ectomycorrhizal fungus Tylospora fibrilosa and several other mycorrhizal fungi were investigated by using 19F nuclear magnetic resonance (NMR) spectroscopy in combination with14C radioisotope-detected high-performance liquid chromatography (14C-HPLC). Under the conditions used in this study T. fibrillosa and some other species degraded 4FBP. 14C-HPLC profiles indicated that there were four major biotransformation products, whereas 19F NMR showed that there were six major fluorine-containing products. We confirmed that 4-fluorobiphen-4′-ol and 4-fluorobiphen-3′-ol were two of the major products formed, but no other products were conclusively identified. There was no evidence for the expected biotransformation pathway (namely, meta cleavage of the less halogenated ring), as none of the expected products of this route were found. To the best of our knowledge, this is the first report describing intermediates formed during mycorrhizal degradation of halogenated biphenyls.

Degradation of the polycyclic aromatic hydrocarbon (PAH) fluorene is retarded in a Scots pine ectomycorrhizosphere

“…A range of EcMF are known to degrade POPs (Meharg & Cairney, 2000), although until now, metabolic pathways have only been determined for 4‐fluorobiphenyl (Green et al ., 1999). In the present study, two of the eight EcMF isolates, L. laccata and T. terrestris , were able to degrade one or more PAH and the metabolites they produced have been characterized.…”

“…Some, but not all, EcMF are able to degrade/mineralize a range of POPs both in axenic culture (Meharg et al ., 1997; Braun‐Lullemann et al ., 1999; Gramss et al ., 1999; Green et al ., 1999) and in their symbiotic state (Meharg et al ., 1997). It has been suggested that, like white‐rot fungi, this is caused by the production of extracellular, nonspecific, oxidative enzymes that enable degradation of complex aromatic polymers, such as lignin, in natural soils (Barr & Aust, 1994; Meharg & Cairney, 2000).…”

“…The aim of this study was to investigate the potential of EcMs to remediate PAH contaminated soils. Since little is known about the degradation pathways of POPs by EcMF (Green et al ., 1999), we first used 14 C‐labelled PAHs, in combination with 14 C‐HPLC and LC‐MS, to determine how eight diverse EcMF degrade PAHs in liquid culture. We then used specially constructed microcosms to study the fate of 14 C‐labelled PAHs in a substrate inoculated with F‐horizon forest‐soil, with Scots pine ( Pinus sylvestris L.) seedlings with and without a naturally established complement of EcMF.…”

Petroleum hydrocarbon contamination in boreal forest soils: a mycorrhizal ecosystems perspective

“…In each case, the direct oxidative activities correlated with production of extracellular enzymes that appeared to metabolize aromatic rings (Braun‐Lüllemann et al , 1999; Gramss et al , 1999). Green et al (1999) reported that the ECM fungus Tylospora fibrillosa degraded 4‐fluorobiphenyl to significant extents via sequential hydroxylation reactions.…”

Degradation of fluorobiphenyl byPseudomonas pseudoalcaligenesKF707

“…Scant information is available regarding the degradation of fluorobiphenyl. Green et al (1999a) investigated the biotransformation of 4‐fluorobiphenyl by various strains of mychorrhizal fungi and determined that a number of fluorinated compounds were formed, including 4‐fluorobiphen‐4′‐ol and 4‐fluorobiphen‐3′‐ol, indicating that the biotransformation involved monooxygenation, but complete mineralization of the substrate was not observed. Kimura et al (1996) demonstrated that enzymes of the Pseudomonas pseudoalcaligenes KF707 Bph pathway transformed 4‐fluorobiphenyl, but the intermediates were not characterized, nor was the ability of the bacterium to grow on the substrate examined.…”