Xerocomus Chrysenteron Research Articles

Elemental and Cu–Zn isotopic compositions of two bolete mushrooms grown on contrasting substrates

We studied elemental and Cu–Zn isotopic compositions of Boletus edulis and Xerocomus chrysenteron mushroom samples collected from three small catchments underlain by contrasting bedrock (leucogranite, amphibolite, and serpentinite). Elements such as Ag, P, K, Zn, S, Cd, and Rb are significantly enriched in the mushroom's fruiting bodies relative to the substrate. All analyzed elements are distributed unevenly within the fruiting bodies, with the cap and sporophore generally containing higher amounts of trace elements. Overall, the studied samples of the B. edulis more efficiently accumulate nutrients and minerals than the X. chrysenteron samples. Concentration of most trace elements in mushrooms is not site-dependent with the exception of Ca, Rb, Ti, Ba and Sr. Isotopic composition of mushrooms is characterized by higher uptake of heavier isotopes of Zn (Δ66Znstipe-soil = 0.48–0.77‰) for the both species, lighter isotopes of Cu (Δ65Custipe-soil = −0.73 to −1.52‰) for B. edulis, and heavier Cu isotopes (Δ65Custipe-soil = +0.37 to +0.43‰) for X. chrysenteron. The B. edulis samples are characterized by (δ65Custipe > δ65Cucap > δ65Cusporophore) and (δ66Znstipe > δ66Zncap > δ66Znsporophore) within-mushroom isotope distribution schemes, whereas the X. chrysenteron samples display different Cu (δ65Custipe < δ65Cucap > δ65Cusporophore) and Zn (δ66Znstipe > δ66Zncap < δ66Znsporophore) isotope distribution schemes. Changes in fungal isotopic signatures relative to the substrate and within the fruiting body suggest that both fungi species fractionate Cu and Zn isotopes with significantly pronounced differences between the species.

Ectomycorrhizal symbioses increase soil calcium availability and water use efficiency of Quercus acutissima seedlings under drought stress

Ectomycorrhizal fungi (EMF) can enhance drought resistance of host plants by increasing nutrient and water absorption. Calcium (Ca) plays a central role in drought stress adaptation, yet it remains unclear how EMF influence Ca uptake of plants under drought stress. We carried out a pot experiment in which Quercus acutissima seedlings were inoculated with or without the ectomycorrhizal (EM) fungus Xerocomus chrysenteron under control and water stress soil moisture conditions in order to investigate how soil Ca availability and plant Ca uptake are modulated by EMF and how this may contribute to drought resistance of the seedlings. We found that soil water-extractable Ca was significantly reduced by drought in non-ectomycorrhizal treatment, while EM treatment significantly increased soil Ca availability and Ca uptake of Quercus acutissima seedlings under drought conditions. Furthermore, seedling water use efficiency (WUE) was positively correlated with soil Ca availability and plant Ca content. Calcium uptake promotion seems to be involved in the mechanisms of drought tolerance enhancement by EMF.

Mushroom Poisoning-A 17 Year Retrospective Study at a Level I University Emergency Department in Switzerland.

The consequences of mushroom poisoning range from mild, mostly gastrointestinal, disturbances to organ failure or even death. This retrospective study describes presentations related to mushroom poisoning at an emergency department in Bern (Switzerland) from January 2001 to October 2017. Gastrointestinal disturbances were reported in 86% of the 51 cases. The National Poisons Information Centre and mycologists were involved in 69% and 61% of the cases, respectively. Identification of the mushroom type/family was possible in 43% of the cases. The most common mushroom family was Boletaceae (n = 21) and the most common mushrooms Xerocomus chrysenteron (n = 7; four being part of a cluster), Clitocybe nebularis, Lepista nuda and Lactarius semisanguifluus (n = 5 each, four being part of a cluster). Poisonous mushrooms included Amanita phalloides (n = 3, all analytically confirmed), Boletus satanas (n = 3), Amanita muscaria (n = 2) and Amanita pantherina (n = 2). There were no fatalities and 80% of the patients were discharged within 24 h. Mushroom poisoning does not appear to be a common reason for emergency consultation and most presentations were of minor severity and related to edible species (e.g., due to incorrect processing). Nevertheless, poisonous mushrooms and severe complications were also recorded. Collaboration with a poison centre and/or mycologists is of great importance, especially in high risk cases.

Mycelial culture of Xerocomus chrysenteron and its metabolites

Subject to analysis was mycelial culture of &lt;i&gt;Xerocomus chrysenteron&lt;/i&gt; and its metabolites which night be of pharmaceutical on toxicological interest. Several groups of metabolites were analysed: steroids, fatty acids, indole desiratives, aminoacid, sugars - using chromatographic analytical methods. Amony others soma interesting idolic substances were detected.

Comprehensive evaluation of antioxidant and antimicrobial properties of different mushroom species

Antioxidant properties of mushroom extracts sequentially isolated by cyclohexane, dichloromethane, methanol, and water from Phaeolus schweinitzii, Inonotus hispidus, Tricholoma columbetta, Tricholoma caligatum, Xerocomus chrysenteron, Hydnellum ferrugineum, Agaricus bisporus and Pleurotus ostreatus were evaluated by DPPH, ABTS+ scavenging capacity, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and Folin–Ciocalteu total phenolic content (TPC) methods. The integrated values (‘antioxidant scores’) for evaluating antioxidant potential of extracts and dry mushroom substances are proposed. Antimicrobial activity was screened against Gram-positive (Bacillus cereus), Gram-negative (Pseudomonas aeruginosa) bacteria and fungi (Candida albicans) by agar diffusion method. The highest antioxidant capacity values (in μM TE/g extract dw) were found for methanol fractions of P. schweinitzii (9.62 ± 0.03 in DPPH; 109 ± 3 in FRAP; 164 ± 1 in ABTS+; 340 ± 3 in ORAC assays) and I. hispidus (9.5 ± 0.04 in DPPH; 54.27 ± 0.46 in ABTS+; 88.31 ± 1.96 in FRAP; 290 ± 1 in ORAC assays). Extracts of other species possessed considerably lower antioxidant activities. The extracts of I. hispidus were more effective against tested microbial species than other mushrooms. In conclusion, our results show that some wild mushrooms might be promising dietary sources of natural antioxidants and antimicrobial agents.

Bioconcentration of mercury by mushroom Xerocomus chrysenteron from the spatially distinct locations: Levels, possible intake and safety

Concentrations of mercury were determined in specimens of Red Cracking Bolete (Xerocomus chrysenteron) (Bull.) Quél. and overlying soil (0–10cm) collected from 22 spatially distributed sites in Poland during 1996–2013 to assess the potential of this species to bioconcentrate Hg and possible intake by humans. The mean Hg concentrations ranged from 80 to 630 for caps and from 28 to 380ng/g dry matter (dm) for stipes. Decrease in the potential of this mushroom species to bioconcentrate Hg both in caps and stipes was observed when the Hg content in soil substratum increased from 15 to 75–94ng/g dm. A maximum median value for bioconcentration factor (BCF) of Hg determined for caps was 18 for soil with Hg content at 15ng/g dm and decreased to 0.97–3.8 for soils that contained Hg at 37–94ng/g dm. Caps of X. chrysenteron consumed at a volume of 300g daily in a week can yield an exposure amount of Hg at 0.0168–0.1323mg (0.00024 to 0.00189mg/kg body mass); these values are well below the provisionally tolerated weekly intake (PTWI) for inorganic Hg.

Degradation and mineralization of DDT by the ectomycorrhizal fungi, Xerocomus chrysenteron

One strain of ectomycorrhizal fungi, Xerocomus chrysenteron, had been investigated for its ability to degrade 1,1,1-trichloro-2,2-bis(4-chlorophe-nyl) ethane (DDT) by measuring unlabeled DDT and identifying its metabolites, and determining the mineralization of [13C]DDT in pure cultures. After 45d incubation, about 55% of the added DDT disappeared from the culture system, less than 5% remained in the nutrient solution, and about 44% was retained in the mycelium. Inoculation with mycelium enhanced the degradation of DDT in soil, and alleviated enrichment of DDT in plants. The metabolites identified by gas chromatography–mass spectrometry were 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (DDD), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), and 4,4′-dichlorobenzophenone (DBP). There were significant differences in the δ13C of released CO2 between [13C]DDT and DDT cultures, which indicated X. chrysenteron was able to mineralize DDT to CO2.

Phenolic, Polysaccharidic, and Lipidic Fractions of Mushrooms from Northeastern Portugal: Chemical Compounds with Antioxidant Properties

Mushrooms do not constitute a significant portion of the human diet, but their consumption continues to increase due to their functional benefits and presence of bioactive compounds. Some of those compounds can be found in the phenolic, polysaccharidic, and lipidic fractions of edible and inedible species. Herein, those fractions of five wild mushrooms (Coprinopsis atramentaria, Lactarius bertillonii, Lactarius vellereus, Rhodotus palmatus, and Xerocomus chrysenteron) from northeastern Portugal were studied for their chemical composition and antioxidant properties. Protocatechuic, p-hydroxybenzoic, p-coumaric, and cinnamic acids were found in the phenolic fraction; rhamnose, xylose, fucose, arabinose, fructose, glucose, manose, mannitol, sucrose, maltose, and trehalose were quantified in polysaccharidic fraction; and linoleic and stearic (only in Lactarius sp.) acids, and β- and γ-tocopherols were the main compounds in the lipidic fraction. C. atramentaria and X. chrysenteron phenolic fractions gave the highest free radical scavenging activity, reducing properties, and lipid peroxidation inhibition in brain homogenates, which is in agreement with its highest content in total phenolics. Furthermore, among the polysaccharidic fractions C. atramentaria also gave the highest antioxidant activity, which is in agreement with its highest total polysaccharides content and sugars obtained after hydrolysis.

Influence of Ectomycorrhizal Fungi on Absorption and Balance of Essential Elements of Pinus tabulaeformis Seedlings in Saline Soil

Pinus tabulaeformis seedlings were grown under a factorial design to measure biomass accumulation and P, Na and K concentrations of plants, with 3 different ectomycorrhizal fungus (EMF) strains (Boletus edulis, Xerocomus chrysenteron and Gomphidius viscidus) and two P treatments (with or without extra P). Growth and mineral nutrition of pine seedlings were stimulated by three EMF under salinity stress. Na concentrations were changed and plant K and P concentrations were increased significantly by EMF. Adding extra P made no difference in accumulation of seedlings biomass, and did not assist element absorption of plants. Although three strains of EMF can all enhance the tolerance of pine seedlings to salinity stress, they may utilize different mechanisms because of different performance in absorption of elements. The increased P and K accumulation and the balance of ion concentrations might be due to the enhanced tolerance of EMF-inoculated plants to saline conditions.

Ecological risk of long-term chlorimuron-ethyl application to soil microbial community: an in situ investigation in a continuously cropped soybean field in Northeast China

Chlorimuron-ethyl has been widely used for the soybean production of China, but less information is available on the possible risk of long-term application of this herbicide. In this paper, soil samples were collected from the plots having been received 30g active component of chlorimuron-ethyl/ha per year for 5 and 10years in a continuously cropped soybean field of Northeast China, with their microbial community analyzed by plate counting, PCR-DGGE, and cloning library. Chlorimuron-ethyl had a higher accumulation in test soils, and the accumulation decreased the CFU of soil bacteria and increased the CFU of soil fungi significantly. The CFU of soil actinomycetes only had a significant decrease in the plot having been received chlorimuron-ethyl for 10years. Under the long-term stress of chlorimuron-ethyl, the diversity and evenness of soil microbial community decreased, and more importantly, some bacterial and fungal species that possibly benefited soybean's growth, e.g., Acidobacteria, γ-proteobacteria, Cortinarius violaceu, Acarospora smaragdula, and Xerocomus chrysenteron decreased or demised, while some species that could induce the obstacle of soybean's continuous cropping, e.g., Fusarium oxysporum, Rhizoctonia solani, and Phytophthora sojae, increased or appeared. Some actinomycetes were inhibited having negative effects on the antagonism between soil microbes. It is considered that due to the longer half-life of chlorimuron-ethyl in soil and the resistance and resilience of soil microbes to short-term environmental stress, long-term in situ investigation rather than laboratory microcosm test or short-term field experiment would be more appropriate to the accurate assessment of the ecological risk of long-term chlorimuron-ethyl application. Further studies should be made on the application mode and duration of chlorimuron-ethyl to reduce the possible ecological risk of applying this herbicide on continuously cropped soybean field.

Taxonomic reconsideration of a sequestrate fungus, Octaviania columellifera, with the proposal of a new genus, Heliogaster, and its phylogenetic relationships in the Boletales

During taxonomic revision of genus Octaviania in Japan we examined herbarium and fresh specimens of O. columellifera and O. asterosperma sensu S. Yoshimi & Y. Doi with morphological and molecular techniques. These two species were identical in both macro- and micromorphological characters and were clearly different from the generally known O. asterosperma. The identity of the two species and their distinctness from O. asterosperma was further supported by both nuclear large subunit and ITS rDNA phylogeny. The molecular analyses also revealed that O. columellifera shares its lineage with the boletoid mushroom-forming Xerocomus chrysenteron complex and that it does not form a monophyletic clade with other Octaviania species. Our morphological reevaluation, including transmission electron microscopic observation of basidiospores, clarified the taxonomic boundary between O. columellifera and other Japanese Octaviania species. Accordingly we propose a new genus, Heliogaster, for O. columellifera with designation of the lectotype. We discuss phylogenetic relationships with Octaviania sensu stricto species and the closely related boletoid (pileate-stipitate) fungi, generic characters of Heliogaster and intraspecific phylogeny.

Soluble protein and acid phosphatase exuded by ectomycorrhizal fungi and seedlings in response to excessive Cu and Cd

Fungi and their symbionts can alleviate heavy metal stress by exuding soluble proteins and enzymes. This study examined the role of soluble protein and acid phosphatase (APase) exuded by Xerocomus chrysenteron, an ectomycorrhizal fungus, and the seedlings of its symbiont, Chinese pine (Pinus tabulaeformis), under conditions of excessive Cu and Cd. The growth type showed that this poorly studied ectomycorrhizal fungus was capable of tolerating high concentrations of Cu, and may be useful in phytoremediation. X. chrysenteron grew well at 80 mg/L Cu, and the EC50 for Cd was 17.82 mg/L. X. chrysenteron also showed enhanced exudation of soluble protein in both isolated and inoculated cultivations under the influence of Cu and Cd. Soluble protein exudation, however, differed under Cu and Cd stress in isolates. In mediums containing Cu, soluble protein exudation increased with concentration, but in mediums containing Cd the content of soluble protein increased to a comparable level at all concentrations. This study demonstrated that soluble protein was related to heavy metal tolerance, although the different ions played different roles. While APase activity in exudates of fungi and seedlings decreased under Cu and Cd stress in comparison to the control, the APase activity in seedlings was maintained by inoculation. Thus, X. chrysenteron facilitated the ability of plant to maintain a normal nutrient uptake, and therefore to protect it from heavy metal toxicity.

Evaluation of the antioxidant activity of four edible mushrooms from the Central Anatolia, Eskisehir – Turkey: Lactarius deterrimus, Suillus collitinus, Boletus edulis, Xerocomus chrysenteron

The methanolic extracts of Lactarius deterrimus, Suillus collitinus, Boletus edulis, Xerocomus chrysenteron were analyzed for their antioxidant activities in different test systems namely β-carotene/linoleic acid, DPPH free radical scavenging, reducing power and metal chelating activities in addition to their total phenolic and flavonoid contents. In β-carotene/linoleic acid and DPPH systems, L. deterrimus and B. edulis showed the strongest activity patterns. Their activities were as strong as the positive controls. The reducing power of the species was excellent. Chelating capacity of the extracts was increased with the increasing concentration. On the other hand, B. edulis found to have the highest phenolic content. Total flavonoid content of S. collitinus found the superior to the other mushrooms.

Levels of eight trace elements in edible mushrooms from a rural area

Eight trace elements were determined using ICP–MS in 78 fruiting body samples of 22 edible mushroom species. The mushrooms were collected from four sites in a rural area, unpolluted by human activity. Median values (dry matter) were as follows: Arsenic (As) 1.45 mg kg–1, barium (Ba) 1.41 mg kg–1, cobalt (Co) 0.28 mg kg–1, copper (Cu) 47.0 mg kg–1, rubidium (Rb) 130 mg kg–1, silver (Ag) 2.95 mg kg–1, thallium (Tl) 0.02 mg kg–1 and vanadium (V) 0.25 mg kg–1. Higher trace element accumulation was observed in samples of Macrolepiota procera, Macrolepiota rhacodes, Lycoperdon perlatum, Lycoperdon gigantea and Xerocomus chrysenteron for As and Cu, and in samples of Cantharellus cibarius and of genera Boletus and Suillus for Rb.

Determination of metal content in wild edible mushroom species from regions of Greece

Eight different species of wild edible mushrooms ( Cantharellus cibarius, Hydnum repandum, Lactarius salmonicolor, Xerocomus chrysenteron, Agaricus cupreobrunneus, Amanita franchetii, Hygrophorus eburneus and Hygrophorus chrysodon) representing seven different families ( Cantharellaceae, Hydnaceae, Boletaceae, Russulaceae, Agaricaceae, Amanitaceae, Hygrophoraceae) growing in Epirus (Ioannina) and West Macedonia (Grevena, Kastoria), regions of Greece were analyzed by atomic absorption spectrometry (AAS) for their metal (Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, Cd, Al, As and Sn) content. All metal concentrations were determined on a dry weight basis (d.w.). The metal content of mushroom samples ranged from 739–1165 μg/g d.w. for Mg, 0.41 to 13.1 μg/g d.w. for Cr, 11.4 to 100 μg/g d.w. for Mn, 46.3 to 317 μg/g d.w. for Fe, not detected–3.34 μg/g d.w. for Co, 0.28 to 10.1 μg/g d.w. for Ni, 3.80 to 32.6 μg/g d.w. for Cu, 35.9 to 96.9 μg/g d.w. for Zn, not detected–1.37 μg/g d.w. for Pb and 0.08 to 0.41 μg/g d.w. for Cd. As, Sn and Al concentrations were under the detection limit of the method used. This research proves that wild edible fungi which consumed traditionally in Epirus (Ioannina) and West Macedonia (Grevena, Kastoria), Greece can be used in well-balanced diets due to their high contents of functional minerals. Also, their low contents of heavy metals (Pb, Cd and As) shows that collection areas are not polluted, therefore all collected edible mushroom species can be unreservedly consumed without any health risk.

Structural Basis for the Carbohydrate Recognition of the Sclerotium rolfsii Lectin

The crystal structure of a novel fungal lectin from Sclerotium rolfsii (SRL) in its free form and in complex with N-acetyl- d-galactosamine (GalNAc) and N-acetyl- d -glucosamine (GlcNAc) has been determined at 1.1 Å, 2.0 Å, and 1.7 Å resolution, respectively. The protein structure is composed of two β-sheets, which consist of four and six β-strands, connected by two α-helices. Sequence and structural comparisons reveal that SRL is the third member of a newly identified family of fungal lectins, which includes lectins from Agaricus bisporus and Xerocomus chrysenteron that share a high degree of structural similarity and carbohydrate specificity. The data for the free SRL are the highest resolution data for any protein of this family. The crystal structures of the SRL in complex with two carbohydrates, GalNAc and GlcNAc, which differ only in the configuration of a single epimeric hydroxyl group, provide the structural basis for its carbohydrate specificity. SRL has two distinct carbohydrate-binding sites, a primary and a secondary. GalNAc binds at the primary site, whereas GlcNAc binds only at the secondary site. Thus, SRL has the ability to recognize and probably bind at the same time two different carbohydrate structures. Structural comparison to Agaricus bisporus lectin–carbohydrate complexes reveals that the primary site is also able to bind the Thomsen-Friedenreich antigen (Galβ1→3GalNAc-α- glycan structures) whereas the secondary site cannot. The features of the molecular recognition at the two sites are described in detail.

Metal/metalloid contamination and isotopic composition of lead in edible mushrooms and forest soils originating from a smelting area

High metal contents in edible mushrooms growing in severely contaminated industrial areas pose an important toxicological risk. In the presented study, trace element (Pb, Cd, Zn, Cu, Ag, As, Se) contents were determined in caps and stipes of three different edible mushroom species ( Boletus edulis Bull. Fr., Xerocomus badius Fr. Gilb., Xerocomus chrysenteron Bull. Quél.). Additionally, information about the chemical fractionation of metals in separate soil horizons and Pb isotopic data from soils and fruiting bodies allowed a more detailed insight on the uptake mechanisms of metals by the studied mushroom species. Total metal and metalloid concentrations in the organic soil horizons reached 36 234 mg Pb kg − 1 ; 11.9 mg Cd kg − 1 ; 519 mg Zn kg − 1 ; 488 mg Cu kg − 1 ; 25.1 mg Ag kg − 1 ; 120 mg As kg − 1 and 5.88 Se mg kg − 1 . In order to evaluate the accumulation capacity of the studied species, bioconcentration factors (BCF) were calculated for separate trace elements. For selected metals (Pb, Cd, Zn, Cu), a modified BCF calculation (using EDTA-extractable concentrations of metals in soil) was proposed. High contents of Pb (up to 165 mg kg − 1 ) and Cd (up to 55 mg kg − 1 ) exceeded all the regulatory limits in all the studied species. This was also the case for Se (up to 57 mg kg − 1 ) in B. edulis. Intensive consumption of this species grown in such polluted areas can therefore pose toxicological risks for human health. A novel finding was that X. badius can act as an Ag accumulating species when grown at polluted sites due to the high concentrations of Ag (up to 190 mg kg − 1 ) in caps. Pb isotopic data showed that Pb originating from the recent air pollution control residues is present mainly in the exchangeable/acid-extractable fraction of the organic horizons and is taken up by fruiting bodies; especially in the case of B. edulis, where fast Pb accumulation occurs. Due to the high species-dependent variations of metal contents, the studied mushrooms are not suitable as bioindicators of environmental pollution.

Laccase and phosphatase activities of the dominant ectomycorrhizal types in a lowland oak forest

The year-round dynamics of laccase and acid phosphatase activities of ectomycorrhizas (EM) were monitored in an oak forest, with a microplate photometric method using individual EM root tips. Among the most frequent and abundant EM morphotypes, those of Lactarius quietus and Cortinarius anomalus showed a peak of laccase activity in spring, while those of Xerocomus chrysenteron displayed highest laccase activities in summer and autumn. In comparison, less seasonal differences were observed in EM acid phosphatase activity. This suggests that the different EM types within the EM community perform complementary functions depending on season.

Quantitation of Nine Organic Acids in Wild Mushrooms

The organic acids composition of six wild edible mushroom species (Amanita caesarea, Boletus edulis, Gyroporus castaneus, Lactarius deliciosus, Suillus collinitus, and Xerocomus chrysenteron) was determined by an HPLC-UV detector method. The results showed that all of the samples presented a profile composed of at least five organic acids: citric, ketoglutaric, malic, succinic, and fumaric acids. Several samples also contained oxalic, ascorbic, quinic, and shikimic acids. In a general way, the quantitation of the identified compounds indicated that malic acid, followed by the pair citric plus ketoglutaric acids, were the main compounds in the analyzed species, with the exception of A. caesarea, in which malic and ascorbic acids were the most abundant compounds. The relative amounts and the presence/absence of each identified compound may be useful for the differentiation of the species.

A molecular method to evaluate basidiomycete laccase gene expression in forest soils

Fungal laccases, exo-enzymes lacking high substrate specificity, play a central role in cycling of soil organic matter. In a precedent work based on a PCR technique on soil DNA extracts, we showed that the highest diversity of laccase genes occurred in the most organic horizon (i.e., O h) of a brown forest soil. In the present article, we develop a method of RNA extraction, RT-PCR, and semi-quantitative PCR to analyze the expression of Basidiomycete laccase genes. We performed a very first assessment of the methodological approach on five cores of the O h horizon of the same brown forest soil. The level of laccase transcripts was heterogeneous amongst the soil cores. Two samples gave strong expression levels, two showed very faint ones, and the last replicate presented no detectable laccase transcripts. A control with a transcript analysis of the actin gene, which is constitutively expressed in fungi, allowed to rule out that the differences in the transcript level of laccases were due to experimental failures or inhibiting substances in the RNA extracts. A cladistic analysis showed that most laccase transcript sequences detected were grouped in two clades closely related to the ectomycorrhizal fungus Xerocomus chrysenteron. Comparison between DNA laccase sequences found in our previous study and RNA laccase sequence profiles found here showed that less than 30% of the laccases genes detected in a soil core were expressed. This preliminary study demonstrates the potential of RT-PCR for gene expression profiling in forest soils. The number of analyzed samples cannot allow us to draw definitive ecological conclusions, but there are some indications that differences between rhizospheric and bulk soil samples (polyphenol abundances, microbial densities, etc.) might be a potential explanation for the variable laccase expression observed.