Metabolism of Pyrene by the Basidiomycete Crinipellis stipitaria and Identification of Pyrenequinones and Their Hydroxylated Precursors in Strain JK375

The degradative activity and adaptation potential of the litter-decomposing fungus Stropharia rugosoannulata

The ability of the litter-decomposing basidiomycete Stropharia rugosoannulata DSM 11372 to degrade a wide range of structurally different environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs: phenanthrene, anthracene, fluorene, pyrene, and fluoranthene), synthetic anthraquinone dyes containing condensed aromatic rings, environmentally relevant alkylphenol and oxyethylated alkylphenol representatives, and oil was demonstrated within the present study. 9,10-Anthraquinone, phenanthrene-9,10-quinone, and 9-fluorenone were identified as products of anthracene, phenanthrene, and fluorene degradation, respectively. Fungal degradation was accompanied by the production of the ligninolytic enzymes: laccase and Mn peroxidase, suggesting their involvement in pollutant degradation. Extracellular polysaccharide(s) (EPS) and emulsifying compound(s) were concomitantly produced. EPS composed of mannose, glucose, and galactose was isolated from the cultivation medium, and its effects on catalytic properties of purified laccase from S. rugosoannulata (the dominating ligninolytic enzyme under the applied conditions) were studied. A simultaneous decrease of K_M and V_max values observed for the enzymatic oxidation of non-phenolic (2,2-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt; ABTS) and phenolic compounds (2,6-dimethoxyphenol) in presence of EPS suggest an interaction of EPS and laccase resulting in a modulation of the catalytic performance of the enzyme, which has, to the best of our knowledge, not been reported before. In line with such a modulation, the laccase-catalyzed oxidation of natural aromatic compounds (veratryl alcohol, adlerol) and environmental pollutants (the alkylphenol representative nonylphenol, the diphenylmethane derivative bisphenol A, and the PAH representative anthracene) was found to be enhanced in presence of EPS. The relevance of such effects for real environmental processes and their implications remain to be investigated.

Polycyclic aromatic hydrocarbons degradation by marine-derived basidiomycetes: optimization of the degradation process

Pyrene and benzo[a]pyrene (BaP) are high molecular weight polycyclic aromatic hydrocarbons (PAHs) recalcitrant to microbial attack. Although studies related to the microbial degradation of PAHs have been carried out in the last decades, little is known about degradation of these environmental pollutants by fungi from marine origin. Therefore, this study aimed to select one PAHs degrader among three marine-derived basidiomycete fungi and to study its pyrene detoxification/degradation. Marasmiellus sp. CBMAI 1062 showed higher levels of pyrene and BaP degradation and was subjected to studies related to pyrene degradation optimization using experimental design, acute toxicity, organic carbon removal (TOC), and metabolite evaluation. The experimental design resulted in an efficient pyrene degradation, reducing the experiment time while the PAH concentration applied in the assays was increased. The selected fungus was able to degrade almost 100% of pyrene (0.08mgmL^-1) after 48h of incubation under saline condition, without generating toxic compounds and with a TOC reduction of 17%. Intermediate metabolites of pyrene degradation were identified, suggesting that the fungus degraded the compound via the cytochrome P450 system and epoxide hydrolases. These results highlight the relevance of marine-derived fungi in the field of PAH bioremediation, adding value to the blue biotechnology.

Biomimetic oxidation of pyrene and related aromatic hydrocarbons. Unexpected electron accepting abilities of pyrenequinones

We present a mild catalytic method to oxidize PAHs and, in particular, pyrene, and we characterize the electron accepting abilities of pyrenequinones both in gas phase and in solution.

Enhanced biotransformation of fluoranthene by intertidally derived Cunninghamella elegans under biofilm-based and niche-mimicking conditions

The aims of the investigation were to ascertain if surface attachment of Cunninghamella elegans and niche intertidal conditions provided in a bioreactor influenced biotransformation of fluoranthene by C. elegans. A newly designed polymethylmethacrylate (PMMA) conico-cylindrical flask (CCF) holding eight equidistantly spaced rectangular strips mounted radially on a circular disc allowed comparison of fluoranthene biotransformation between CCFs with a hydrophobic surface (PMMA-CCF) and a hydrophilic glass surface (GS-CCF) and a 500-ml Erlenmeyer flask (EF). Fluoranthene biotransformation was higher by 22-fold, biofilm growth was higher by 3-fold, and cytochrome P450 gene expression was higher by 2.1-fold when C. elegans was cultivated with 2% inoculum as biofilm culture in PMMA-CCF compared to planktonic culture in EF. Biotransformation was enhanced by 7-fold with 10% inoculum. The temporal pattern of biofilm progression based on three-channel fluorescence detection by confocal laser scanning microscopy demonstrated well-developed, stable biofilm with greater colocalization of fluoranthene within extracellular polymeric substances and filaments of the biofilm grown on PMMA in contrast to a glass surface. A bioreactor with discs rotating at 2 revolutions per day affording 6-hourly emersion and immersion mimicked the niche intertidal habitat of C. elegans and supported biofilm formation and transformation of fluoranthene. The amount of transformed metabolite was 3.5-fold, biofilm growth was 3-fold, and cytochrome P450 gene expression was 1.9-fold higher in the process mimicking the intertidal conditions than in a submerged process without disc rotation. In the CCF and reactor, where biofilm formation was comparatively greater, higher concentration of exopolysaccharides allowed increased mobilization of fluoranthene within the biofilm with consequential higher gene expression leading to enhanced volumetric productivity.

Microbial communities to mitigate contamination of PAHs in soil--possibilities and challenges: a review

BACKGROUND, AIM, AND SCOPE

Although highly diverse and specialized prokaryotic and eukaryotic microbial communities in soil degrade polycyclic aromatic hydrocarbons (PAHs), most of these are removed slowly. This review will discuss the biotechnological possibilities to increase the microbial dissipation of PAHs from soil as well as the main biological and biotechnological challenges.

DISCUSSION AND CONCLUSIONS

Microorganism provides effective and economically feasible solutions for soil cleanup and restoration. However, when the PAHs contamination is greater than the microbial ability to dissipate them, then applying genetically modified microorganisms might help to remove the contaminant. Nevertheless, it is necessary to have a more holistic review of the different individual reactions that are simultaneously taking place in a microbial cell and of the interactions microorganism-microorganism, microorganism-plant, microorganism-soil, and microorganisms-PAHs.

PERSPECTIVES

Elucidating the function of genes from the PAHs-polluted soil and the study in pure cultures of isolated PAHs-degrading organisms as well as the generation of microorganisms in the laboratory that will accelerate the dissipation of PAHs and their safe application in situ have not been studied extensively. There is a latent environmental risk when genetically engineered microorganisms are used to remedy PAHs-contaminated soil.

Degrading ability of oligocyclic aromates by Phanerochaete sordida selected via screening of white rot fungi

Seventy-nine white rot strains were screened to determine if they had the potential for use in the degradation of oligocyclic aromates (PAHs) by measuring their dye-decoloration rate. Fourteen strains that were selected based on their dye-decoloration rate were then evaluated for the ability to tolerate various levels of PAHs spiked in agar medium. The ability of white rot fungi to degrade 3- or 4-ring PAHs (anthracene, phenanthrene, fluoranthene, pyrene) was determined. Two strains of Phanerochaete sordida (KUC8369, KUC8370) were possible PAHs degraders, degrading a significantly greater amount of phenanthrene and fluoranthene than the culture collection strain P. chrysosporium (a known PAHs degrader). The production of manganese peroxidase, the only extracellular ligninolytic enzyme detected during the cultivation, was evaluated.

Initial Oxidation Products in the Metabolism of Pyrene, Anthracene, Fluorene, and Dibenzothiophene by the White Rot Fungus Pleurotus ostreatus

The initial metabolites in the degradation of pyrene, anthracene, fluorene, and dibenzothiophene by Pleurotus ostreatus were isolated by high-pressure liquid chromatography and characterized by UV-visible, gas-chromatographic, mass-spectrometric, and (sup1)H nuclear magnetic resonance spectral techniques. The metabolites from pyrene, dibenzothiophene, anthracene, and fluorene amounted to 45, 84, 64, and 96% of the total organic-solvent-extractable metabolites, respectively. Pyrene was metabolized predominantly to pyrene trans-4,5-dihydrodiol. Anthracene was metabolized predominantly to anthracene trans-1,2-dihydrodiol and 9,10-anthraquinone. In contrast, fluorene and dibenzothiophene were oxidized at the aliphatic bridges instead of the aromatic rings. Fluorene was oxidized to 9-fluorenol and 9-fluorenone; dibenzothiophene was oxidized to the sulfoxide and sulfone. Circular dichroism spectroscopy revealed that the major enantiomer of anthracene trans-1,2-dihydrodiol was predominantly in the S,S configuration and the major enantiomer of the pyrene trans-4,5-dihydrodiol was predominantly R,R. These results indicate that the white rot fungus P. ostreatus initially metabolizes polycyclic aromatic hydrocarbons by reactions similar to those previously reported for nonligninolytic fungi. However, P. ostreatus, in contrast to nonligninolytic fungi, can mineralize these polycyclic aromatic hydrocarbons. The identity of the dihydrodiol metabolites implicates a cytochrome P-450 monooxygenase mechanism.

Bioaccumulation and biotransformation of pyrene and 1-hydroxypyrene by the marine whelk Buccinum undatum

The fates of a phenolic contaminant and its hydrocarbon precursor have rarely been compared, especially in an invertebrate species. Two groups of Buccinum undatum were exposed to equimolar amounts of pyrene and 1-hydroxypyrene over 15 d through their diets. Tissue extracts from the muscle and visceral mass were analyzed by liquid chromatography with fluorescence and mass spectrometry detection. Nine biotransformation products were detected in animals from both exposures. These included 1-hydroxypyrene, pyrene-1-sulfate, pyrene-1-glucuronide, pyrene glucose sulfate, two isomers each of pyrenediol sulfate and pyrenediol disulfate, and one isomer of pyrenediol glucuronide sulfate. These compounds represent a more complex metabolic pathway for pyrene than is typically reported. Diconjugated metabolites were as important in animals exposed to pyrene as in those exposed to 1-hydroxypyrene. Biotransformation products represented >90% of the material detected in the animals and highlight the importance of analyzing metabolites when assessing exposure. A mean of only 2 to 3% of the body burden was present in muscle compared with the visceral mass of both groups. The analytical methods were sufficiently sensitive to detect biotransformation products both in laboratory control whelks and in those sampled offshore. The tissue distribution of [(14)C]pyrene was also studied by autoradiography. Radioactivity was present primarily in the digestive and excretory system of the whelks and not in the gonads or muscle tissue.

Fungal PAH-metabolites resist mineralization by soil microorganisms

This study investigated the mineralization of water-soluble polycyclic aromatic hydrocarbon (PAH) metabolites produced by the soil fungus Cunninghamella elegans. Eleven soil fungi were screened for their ability to metabolize (14)C-phenanthrene, (14)C-fluoranthene, and (14)C-pyrene into water-soluble compounds. Eight fungi produced water-soluble metabolites from all or some of the PAHs. The composition of the water-soluble PAH-metabolites from the most effective solubilizer C. elegans was analyzed by an ultraperformance liquid chromatograph interfaced to a quadrupole time-of-flight mass spectrometer. Thirty-eight metabolites were detected. All of 34 identified metabolites were sulfate-conjugated. The mineralization of (14)C-metabolites, produced by C. elegans, was compared to mineralization of the parent (14)C-PAHs in soil slurries. It was hypothesized that the increased bioavailability and metabolic activation of the metabolites would increase mineralization in soil slurries compared to mineralization of the parent PAHs. Unexpectedly, the mineralization of the (14)C-metabolites was in all cases extremely slow compared to the mineralization of the parent (14)C-PAHs. Slow (14)C-metabolite mineralization was not caused by metabolite toxicity, neither was cometabolic mineralization of (14)C-metabolites stimulated by the presence of active PAH-degraders. High water solubility, low lipophilicity, and extremely slow mineralization of the metabolites indicate a potential problem of leaching of fungal PAH-metabolites to the groundwater.

Cooperativity in oxidation reactions catalyzed by cytochrome P450 1A2: highly cooperative pyrene hydroxylation and multiphasic kinetics of ligand binding

Rabbit liver cytochrome P450 (P450) 1A2 was found to catalyze the 5,6-epoxidation of alpha-naphthoflavone (alphaNF), 1-hydroxylation of pyrene, and the subsequent 6-, 8-, and other hydroxylations of 1-hydroxy (OH) pyrene. Plots of steady-state rates of product formation versus substrate concentration were hyperbolic for alphaNF epoxidation but highly cooperative (Hill n coefficients of 2-4) for pyrene and 1-OH pyrene hydroxylation. When any of the three substrates (alphaNF, pyrene, 1-OH pyrene) were mixed with ferric P450 1A2 using stopped-flow methods, the changes in the heme Soret spectra were relatively slow and multiphasic. Changes in the fluorescence of all of the substrates were much faster, consistent with rapid initial binding to P450 1A2 in a manner that does not change the heme spectrum. For binding of pyrene to ferrous P450 1A2, the course of the spectra revealed sequential changes in opposite directions, consistent with P450 1A2 being involved in a series of transitions to explain the kinetic multiphasicity as opposed to multiple, slowly interconverting populations of enzyme undergoing the same event at different rates. Models of rabbit P450 1A2 based on a published crystal structure of a human P450 1A2-alphaNF complex show active site space for only one alphaNF or for two pyrenes. The spectral changes observed for binding and hydroxylation of pyrene and 1-OH pyrene could be fit to a kinetic model in which hydroxylation occurs only when two substrates are bound. Elements of this mechanism may be relevant to other cases of P450 cooperativity.

Mycelial pellet formation by Penicillium ochrochloron species due to exposure to pyrene

Five indigenous fungal strains with characteristics of the genus Penicillium capable of degrading and utilizing pyrene, as sole carbon source were isolated from soil of a former gas work site. Two strains were identified as Penicillium ochrochloron. One of the strains was able to degrade a maximum of 75% of 50 mg l(-1) pyrene at 22 degrees C during 28 days of incubation. The presence of pyrene in the medium resulted in an aggregation of hyphae into pellets by the two Penicillium ochrochloron strains. Formation of pellets was observed after 48 h of incubation with difference in size and texture between the two strains. This indicated the individual variation within the same genus of fungi. However, remaining strains did not show this behavior even though they were capable of utilizing pyrene as sole carbon source. The macro- and microscopic morphology of fungal pellets was studied using scanning electron microscopy. It was found that the addition of varying concentration of pyrene ranging from 10 to 50 mg l(-1) in the medium influenced shape and structure of the mycelial pellets. A two-fold increase in hyphal branching (with concomitant decrease in the average hyphal growth unit) was observed at a concentration of 10mg l(-1). The relevance of fungal growth and morphology for bioremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated sites are discussed.

Studies in the biodegradation of 5 PAHs (phenanthrene, pyrene, fluoranthene, chrysene und benzo(a)pyrene) in the presence of rooted poplar cuttings

Cuttings of Populus nigra L. cv. Loenen were cultivated in sand treated with one of the following PAHs: phenanthrene (Phen), fluoranthene (Flt), pyrene (Pyr), chrysene (Chr) and benzo[a]pyrene (BaP). The PAHs were applied at varying levels of concentration to each test series. After 6 weeks the concentration and the distribution of the PAHs in the substrate of the various sets of tests were compared with the concentration in the substrate of the control. Additionally the substrate and the plant roots were tested for evidence of degradation products of PAHs. The results revealed that the levels of concentration of Phen and Pyr detected in the substrate surrounding the roots was in some cases significantly lower than in the corresponding section of substrate in the unplanted set (= control). This phenomenon did not occur for Flt and BaP and in the case of Chr only in those substrates, which had been treated with the highest levels of concentration. As the presence of lesser amounts of Phen and Pyr in the plant pots cannot only be attributed to their accumulation and metabolism in the roots, it is fair to assume that the chemical transformation of these three PAHs took place outside the roots. The set of tests treated with Phen revealed the presence of 2- or 3-hydroxy-Phen (main components), a hydroxy-methoxy-Phen, 9,10-Phenanthrenequinone and one unidentified compound in metabolite form. Altogether eleven metabolites of Pyr were identified in the root extracts, which can be divided into three groups: 1-Hydroxy-Pyr and derivatives, dihydroxy-Pyr and derivatives and ring fission products (4-Hydroxy-Pyr and a derivative of the 4-Phen-carbonic acid). However, the metabolite mass detected for Phen and Pyr represents only an insignificant percentage in comparison with the lesser amounts of PAHs observed in the planted set of tests. This indicates that the three PAHs were reduced to lower molecular compounds, which are methodically impossible to record, and subsequently translocated to other parts of the plant and integrated into the biomass. Although no lesser amount for Flt and BaP was found in the plant pots, 1-Hydroxy-Flt, an unidentified compound of Flt and 1-Methoxy-BaP were detected. These are presumably end products which were enhanced in the roots. It was not possible to identify any transformation products of Chr. It can be assumed that the majority of metabolites were not synthesised in the roots but are a result of microbial degradation in the rhizosphere. The test plants improved the conditions for the biotransformation of Phen and Pyr significantly and accumulated Flt, Pyr, Chr and BaP in their roots. It can therefore be concluded that the use of plants in the bioremediation of contaminated soils is a promising option.

Degradation of pyrene by indigenous fungi from a former gasworks site

Indigenous fungi isolated from soil of a former gasworks site were investigated in submerged cultures with pyrene as the sole carbon source. Five fungal strains capable of degrading pyrene included one strain of Trichoderma harzianum and four strains with characteristics of the genus Penicillium. These are identified as Penicillium simplicissimum, Penicillium janthinellum, Penicillium funiculosum and Penicillium terrestre. A maximum of 75% of 50 mg l(-1) and 67% of 100 mg l(-1) of pyrene was removed by the fast degrading strain P. terrestre at 22 degrees C during 28 days of incubation. The slower degrader P. janthinellum was able to remove 57% of 50 mg l(-1) and about 31.5% of 100 mg l(-1) pyrene. Degradation of pyrene is directly correlated with biomass development. To the best of our knowledge, this is the first time that fungi have been reported to use pyrene as the sole carbon and energy source. They may be ideal candidates for effective bioremediation of polycyclic aromatic hydrocarbons.

Pyrene degradation by yeasts and filamentous fungi

The saprotrophic soil fungi Fusarium solani (Mart.) Sacc., Cylindrocarpon didymum (Hartig) Wollenw, Penicillium variabile Sopp. and the yeasts Rhodotorula glutinis (Fresenius) Harrison and Rhodotorula minuta (Saito) Harrison were cultured in mineral medium with pyrene. The remaining pyrene concentrations were periodically determined during 20 incubation days, using HPLC. To assess the metabolism of pyrene degradation we added 0.1 microCi of [4,5,9,10] 14C-pyrene to each fungi culture and measured the radioactivity in the volatile organic substances, extractable, aqueous phase, biomass and 14CO2 fractions. The assays demonstrated that F. solani and R. glutinis metabolized pyrene as a sole source of carbon. Differences in their activities at the beginning of the cultures disappeared by the end of the experiment, when 32 and 37% of the original pyrene concentration was detected, for the soil fungi and yeasts, respectively. Among the filamentous fungi, F. solani was highly active and oxidized pyrene; moreover, small but significant degradation rates were observed in C. didymum and P. variahile cultures. An increase in the 14CO2 evolution was observed at the 17th day with cosubstrate. R. glutinis and R. minuta cultures showed similar ability to biotransform pyrene, and that 35% of the initial concentration was consumed at the end of the assay. The same results were obtained in the experiments with or without glucose as cosubstrate.

Biodegradation of pyrene by sediment fungi

Micromycetes were isolated from PAHS-contaminated sediment and identified. They were investigated for pyrene degradation (10 mg l-1) in liquid synthetic medium for two days. Among the 41 strains isolated, 10 highly degraded pyrene (> 2.4 mg g-1 dry weight): two Zygomycetes (Mucor racemosus, M. racemosus var. sphaerosporus), 6 Deuteromycetes (Gliocladium virens, Penicillium simplicissimum, P. janthinellum, Phialophora alba, P. hoffmannii, Trichoderma harzianum), a Dematiaceae (Scopulariopsis brumptii) and a Sphaeropsidale (Coniothyrium fuckelii). Zygomycetes appeared as one of the most efficient taxonomic groups, especially with Mucor racemosus. Penicillium crustosum was the only strain that did not degrade pyrene. Among the 10 fungi which were performant for pyrene degradation, nine were not yet reported in the literature and showed a real value for PAH remediation.

Cytochrome P450 enzyme systems in fungi

The involvement of cytochrome P450 enzymes in many complex fungal bioconversion processes has been characterized in recent years. Accordingly, there is now considerable scientific interest in fungal cytochrome P450 enzyme systems. In contrast to S. cerevisiae, where surprisingly few P450 genes have been identified, biochemical data suggest that many fungi possess numerous P450 genes. This review summarizes the current information pertaining to these fungal cytochrome P450 systems, with emphasis on the molecular genetics. The use of molecular techniques to improve cytochrome P450 activities in fungi is also discussed.

Comparison of acute toxicity and genotoxic concentrations of single compounds and waste elutriates using the Microtox/Mutatox test system

The Mutatox test has been developed by Microbics Corp., U.S.A., in addition to the widely used acute toxicity test Microtox. The Mutatox test indicates the presence of any material in a test sample that causes genetic damage to dark variants of the luminescent bacteria Vibrio fischeri. As the Microtox test is less time-consuming and more cost-effective than the Mutatox test, the possibility of using the EC50 measured by Microtox for range-finding of genotoxic concentrations for the Mutatox test was examined. Both tests were applied on single compounds and several waste elutriates. The genotoxic potential of two PAH metabolites--1-hydroxypyrene and 9-fluorenone-1-carboxylic acid--was detected. According to the present results the highest concentration of a sample in the Mutatox test should in general exceed the EC50 by about 5-10 times. Elutriates were submitted to analyses of TOC, heavy metals, phenols, and PAH; additionally GC/MS screening analyses were carried out. In most cases correlations of ecotoxicological effects with single contaminants were not possible, but it can be assumed that these effects were produced by the interaction of inorganic and organic compounds present in the elutriates.

Comparison of phenanthrene and pyrene degradation by different wood-decaying fungi

The degradation of phenanthrene and pyrene was investigated by using five different wood-decaying fungi. After 63 days of incubation in liquid culture, 13.8 and 4.3% of the [ring U-14C]phenantherene and 2.4 and 1.4% of the [4,5,9,10-14C]pyrene were mineralized by Trametes versicolor and Kuehneromyces mutabilis, respectively. No 14CO2 evolution was detected in either [14C]phenanthrene or [14C]pyrene liquid cultures of Flammulina velutipes, Laetiporus sulphureus, and Agrocybe aegerita. Cultivation in straw cultures demonstrated that, in addition to T. versicolor (15.5%) and K. mutabilis (5.0%), L. sulphureus (10.7%) and A. aegerita (3.7%) were also capable of mineralizing phenanthrene in a period of 63 days. Additionally, K. mutabilis (6.7%), L. sulphureus (4.3%), and A. aegerita (3.3%) mineralized [14C]pyrene in straw cultures. The highest mineralization of [14C] pyrene was detected in straw cultures of T. versicolor (34.1%), which suggested that mineralization of both compounds by fungi may be independent of the number of aromatic rings. Phenanthrene and pyrene metabolites were purified by high-performance liquid chromatography and identified by UV absorption, mass, and 1H nuclear magnetic resonance spectrometry. Fungi capable of mineralizing phenanthrene and pyrene in liquid culture produced enriched metabolites substituted in the K region (C-9,10 position of phenanthrene and C-4,5 position of pyrene), whereas all other fungi investigated produced metabolites substituted in the C-1,2, C-3,4, and C-9,10 positions of phenanthrene and the C-1 position of pyrene.

Novel metabolites in phenanthrene and pyrene transformation by Aspergillus niger

Aspergillus niger, isolated from hydrocarbon-contaminated soil, was examined for its potential to degrade phenanthrene and pyrene. Two novel metabolites, 1-methoxyphenanthrene and 1-methoxypyrene, were identified by conventional chemical techniques. Minor metabolites identified were 1- and 2-phenanthrol and 1-pyrenol. No 14CO2 evolution was observed in either [14C]phenanthrene or [14C]pyrene cultures.

Metabolism of pyrene by basidiomycetous fungi of the generaCrinipellis,Marasmius, andMarasmiellus

The ability of different species and strains of the genus Crinipellis and the related genera Marasmius and Marasmiellus to metabolize pyrene was investigated. The metabolism of pyrene and the nature of metabolites formed were strain specific and depended on the culture medium. The following metabolites of pyrene were detected in the cultures: 1-hydroxypyrene, 1-pyrenylsulfate, 1,6- and 1,8-dihydroxypyrene and the corresponding quinones, trans-4,5-dihydro-4,5-dihydroxypyrene, and two transformation products which have never before been detected, 6-hydroxypyrene-1-sulfate and pyrene-1,6-disulfate. In addition, several not yet identified pyrene metabolites were produced by some strains.Key words: polycyclic aromatic hydrocarbons, pyrene, basidiomycetes, metabolism, transformation products.

The biotransformation of chrysene to trans-1,2-dihydroxy-1,2-dihydrochrysene by filamentous fungi

The purpose of this study was to assess the ability of filamentous fungi isolated from petroleum-contaminated soils to oxidize chrysene. Only 4 of the 17 isolates known to oxidize pyrene and benzo[a]pyrene were found to produce polar products when incubated in the presence of chrysene and Tween 80: Penicillium janthinellum, Syncephalastrum racemosum, and 2 Penicillium spp. Trows-1,2-dihydroxy-1,2-dihydrochrysene was identified by 1H-NMR as one of three fungal metabolites. The extent of bioconversion to diol was approximately 3% of chrysene in 6 days. Experiments to increase chrysene oxidation with other polycyclic aromatic hydrocarbons were not successful. To our knowledge, this is the first identification of a chrysene metabolite from any microorganism and the first report of fungal oxidation of chrysene.Key words: chrysene, polycyclic aromatic hydrocarbons, filamentous fungi, bioremediation, cytochrome P450.

Mineralization of Polycyclic Aromatic Hydrocarbons by the White Rot Fungus Pleurotus ostreatus

The white rot fungus Pleurotus ostreatus was able to mineralize to (sup14)CO(inf2) 7.0% of [(sup14)C]catechol, 3.0% of [(sup14)C]phenanthrene, 0.4% of [(sup14)C]pyrene, and 0.19% of [(sup14)C]benzo[a]pyrene by day 11 of incubation. It also mineralized [(sup14)C]anthracene (0.6%) much more slowly (35 days) and [(sup14)C]fluorene (0.19%) within 15 days. P. ostreatus did not mineralize fluoranthene. The activities of the enzymes considered to be part of the ligninolytic system, laccase and manganese-inhibited peroxidase, were observed during fungal growth in the presence of the various polycyclic aromatic hydrocarbons. Although activity of both enzymes was observed, no distinct correlation to polycyclic aromatic hydrocarbon degradation was found.

Pyrene Metabolism in Crinipellis stipitaria : Identification of trans -4,5-Dihydro-4,5-Dihydroxypyrene and 1-Pyrenylsulfate in Strain JK364

The isolation and identification of two novel metabolites in the fungal metabolism of pyrene are described. The plant-inhabiting basidiomycete Crinipellis stipitaria JK364 metabolized pyrene, a polycyclic aromatic hydrocarbon containing four rings, when grown in submerged cultures in a medium containing malt extract, glucose, and yeast extract. In experiments with [ 14 C] pyrene, after 7 days of incubation 40% of the labeled substrate was converted into organic solvent-extractable metabolites. Metabolites isolated from cultures grown with pyrene were identified as 1-pyrenylsulfate and trans -4,5-dihydro-4,5-dihydroxypyrene. 1-Hydroxypyrene, the precursor of 1-pyrenylsulfate, was also detected. 1-Pyrenylsulfate was isolated from mycelial extracts, whereas trans -4,5-dihydro-4,5-dihydroxypyrene was recovered from the culture filtrate. Identification of the compounds was based on their UV spectra, mass spectra, and nuclear magnetic resonance spectra. This is the first report on the detoxification of a polycyclic aromatic hydrocarbon by a plant-inhabiting basidiomycete. The occurrence of 1-pyrenylsulfate and trans -4,5-dihydro-4,5-dihydroxypyrene among fungal metabolites of pyrene is also new.