Quantifying Hg within ectomycorrhizal fruiting bodies, from emergence to senescence

Total mercury and methylmercury (MeHg) in braised and crude Boletus edulis carpophores during various developmental stages

We collected and processed Boletus edulis (King Bolete) carpophores grouped in four batches based on their developmental stage (button stage, young-white, large-white, and large-yellow). The study aimed, for the first time, to examine the B. edulis content and effect of braising and to estimate the intake of total mercury (THg) and methylmercury (MeHg) from a single meal based on whole (wet) weight (ww) and dry weight (dw). In braised carpophores, THg concentrations ranged from 0.2668 ± 0.0090 to 0.5434 ± 0.0071 mg kg-1 ww at different developmental stages, whereas crude products concentrations ranged from 0.1880 ± 0.0247 to 0.2929 ± 0.0030 mg kg-1 ww. The button stage crude carpophores were more highly contaminated with THg than at later stages of maturity, but MeHg levels were lower (p < 0.0001). On the other hand, braised button stage carpophores showed more MeHg than at later maturity stages. MeHg contributed at 1.9 ± 0.7% in THg in crude mushrooms and at 1.4 ± 0.3% in braised meals. The effect of braising was to increase the average THg and MeHg contents in fresh mushroom meals by 52 ± 31% and 53 ± 122% respectively, but a reduction of 40 ±14% and 40 ± 49% respectively was seen on a dw basis. The potential intakes of THg and MeHg from braised meals of B. edulis studied were small and considered safe.

Nutritional and Other Trace Elements and Their Associations in Raw King Bolete Mushrooms, Boletus edulis

The occurrence and associations of Ag, As, Ba, Bi, Cd, Co, Cu, Cs, Hg, Ni, Pb, Rb, Sb, Sr, Tl, U, V, W, and Zn, including data that have not been previously reported on Be, Hf, In, Li, Mo, Nb, Sn, Ta, Th, Ti and Zr, and the sum of (14) rare earth elements (ƩREE), were studied in a spatially diverse collection of the B. edulis caps, stipes, and whole fruiting bodies using a validated procedure with measurement by quadrupole ICP-MS. Toxic Cd and Pb were in B. edulis at concentrations below limits set by the European Union in regulations for raw cultivated mushrooms, while Ag, As, Hg, Sb, Tl, and U, which are not regulated, were at relatively low or typical levels as is usually found in mushrooms from an unpolluted area. The elements Be, Bi, Ga, Ge, Hf, In, Nb, Ta, Th, and W, and also ƩREEs, were found at relatively low concentrations in B. edulis, i.e., with levels from below 0.1 to below 0.01 mg kg-1 dw, and for Ʃ14 REEs, the median was 0.31 mg kg-1 dw. The composite samples of caps showed Ag, Cd, Cu, Cs, Ga, Ge, Hg, Mo, Ni, Rb, Sb, Ti, and Zn at higher concentrations than stipes, while Ba, Co, Hf, Sr, Tl, and Zr were found at higher concentrations in stipes than caps (p < 0.05). Mushrooms were characterized by a low coefficient of variation (CV) of below 20%, between sites for concentrations of As, Cu, Ge, Hg, Ni, V, and Zn, while substantial differences (CV > 100%) were found for Ba, Bi, Co, Hf, Zr, and ƩREEs, and an intermediate variation was found for Sr, W, and U. Principal component analysis performed on mushrooms allowed differentiation with respect to 13 collection sites and separation of a consignment that was specifically contaminated, possibly due to a legacy pollution, with significantly higher levels of Ba, Co, Ga, Li, Nb, Ni, Sr, Th, Ti, Y, Zr, and ƩREEs, and another due to possible recent pollution (Pb-gasoline and also Ni); two due to geological contamination because of the Bi, In, Sc, Sb, Sn, Ta, V and W; and one more, the Sudety Mts. site, which was considered as "geogenic/anthropogenic" due to Ag, As, Be, Cd, Cs, Ni, Pb, Rb, Tl, and U.

Mercury and selenium in developing and mature fruiting bodies of Amanita muscaria

Both mercury (Hg) and selenium (Se) occur in many mushroom species, but the morphological distribution of these elements during different developmental stages of the fruiting bodies is not known. Although Amanita muscaria can be consumed after suitable processing, they are often ignored by mushroom foragers, leaving an abundance for investigative study. Multiple specimens in each of six developmental stages (button to fully mature) were collected in excellent condition during a single morning from the same forested location and composited. With an average of 30 specimens per composite, and low temporal, spatial, and measurement uncertainty, the data are likely to be representative of the typical concentrations of Hg and Se for each developmental stage. Hg (range 0.58-0.74 mg kg-1 dry weight cap; 0.33 to 0.44 mg kg-1 dw stipe) and Se (range 8.3-11 mg kg-1 dw cap; 2.2 to 4.3 mg kg-1 dw stipe) levels were observed to vary during the developmental stages, and the variability may relate to the demands in growth. In common with some other species, the lower stipe concentrations may be consistent with nutrient/contant transport and support functions. Both Hg and Se levels were lowest during periods of maximum sporocarp growth. Selenium occurs at almost an order of magnitude greater levels than Hg. Due to its role in mitigating the effects of Hg toxicity, this property is of significance to those who consume the species either for nutritional, medicinal, or recreational purposes, although the losses of both these elements during processing are not known.

Mercury in traditionally foraged species of fungi (macromycetes) from the karst area across Yunnan province in China

The objective of this study is to better quantify the occurrence, intake, and potential risk from Hg in fungi traditionally foraged in SW China. The concentrations and intakes of Hg were measured from 42 species including a "hard" flesh type polypore fungi and a" soft" flesh type edible species that are used in traditional herbal medicine, collected during the period 2011-2017. Three profiles of forest topsoil from the Zhenyuan site in 2015 and Changning and Dulong sites in 2016 were also investigated. The concentrations of Hg in composite samples of polypore fungi were usually below 0.1 mg kg-1 dry weight (dw) but higher levels, 0.11 ± 0.01 and 0.24 ± 0.00 mg kg-1 dw, were noted in Ganoderma applanatum and Amauroderma niger respectively, both from the Nujiang site near the town of Lanping in NW Yunnan. Hg concentrations in Boletaceae species were usually well above 1.0 mg kg-1 dw and as high as 10 mg kg-1 dw. The quality of the mushrooms in this study in view of contamination with Hg showed a complex picture. The "worst case" estimations showed probable intake of Hg from 0.006 μg kg-1 body mass (bm) ("hard" type flesh) to 0.25 μg kg-1 bm ("soft" flesh) on a daily basis for capsulated products, from 17 to 83 μg kg-1 bm ("soft" flesh) in a meal ("hard" type flesh mushrooms are not cooked while used in traditional herbal medicine after processing), and from 0.042 to 1.7 and 120 to 580 μg kg-1 bm on a weekly basis, respectively. KEY POINTS: • Polypore species were slightly contaminated with Hg. • Hg maximal content in the polypore was < 0.25 mg kg-1 dry weight. • Many species from Boletaceae family in Yunnan showed elevated Hg. • Locals who often eat Boletus may take Hg at a dose above the daily reference dose.

Interactions between Hg and soil microbes: microbial diversity and mechanisms, with an emphasis on fungal processes

Mercury (Hg) is a highly toxic metal with no known biological function, and it can be highly bioavailable in terrestrial ecosystems. Although fungi are important contributors to a number of soil processes including plant nutrient uptake and decomposition, little is known about the effect of Hg on fungi. Fungi accumulate the largest amount of Hg and are the organisms capable of the highest bioaccumulation of Hg. While referring to detailed mechanisms in bacteria, this mini-review emphasizes the progress made recently on this topic and represents the first step towards a better understanding of the mechanisms underlying Hg tolerance and accumulation in fungal species and hence on the role of fungi within the Hg cycle at Hg-contaminated sites. KEY POINTS: • The fungal communities are more resilient than bacterial communities to Hg exposure. • The exposure to Hg is a threat to microbial soil functions involved in both C and nutrient cycles. • Fungal (hyper)accumulation of Hg may be important for the Hg cycle in terrestrial environments. • Understanding Hg tolerance and accumulation by fungi may lead to new remediation biotechnologies.

Contamination, bioconcentration and distribution of mercury in Tricholoma spp. mushrooms from southern and northern regions of Europe

The contamination, bio-concentration and distribution of mercury (Hg) in wild mushrooms of the genus Tricholoma such as T. equestre, T. portentosum, T. columbeta, and T. terreum were studied, and the possible dietary intake and risk for human consumers in Europe was estimated. Mushrooms, together with the associated forest topsoils were collected from 10 unpolluted and geographically distant areas, far from local or regional emission sources, in Poland (2 sites) and Croatia (8 sites). The Hg contents were in the range 0.10 ± 0.06 to 0.71 ± 0.34 mg kg^-1 dry matter in caps and 0.04 ± 0.02 to 0.38 ± 0.13 mg kg^-1 in stems. The corresponding topsoil concentrations varied over a relatively narrow range between sites, from 0.013 ± 0.003 to 0.028 ± 0.006 mg kg^-1 dry matter. Overall, the study results showed low levels of mercury both, in edible Tricholoma mushrooms and forest topsoils from background (unpolluted) forested areas in Croatia and Poland. The morphological distribution showed considerably greater concentrations of mercury in the caps relative to the stems with ratios ranging from 1.6 ± 0.6 to 3.9 ± 1.8. T. equestre showed good ability to bioconcentrate Hg, with bioconcentration factors (BCF) values in the range 18 ± 7 to 37 ± 18. The data suggests that Tricholoma mushrooms from unpolluted areas in southern and northern regions of Europe can be considered as a low risk food from the point of view of the tolerable Hg intake.

Metallic and metalloid elements in various developmental stages of Amanita muscaria (L.) Lam

There is growing evidence that mushrooms (fruiting bodies) can be suitable for biogeochemical prospecting for minerals and as indicators of heavy metal and radioactive contaminants in the terrestrial environment. Apart from the nutritional aspect, knowledge of accumulation dynamics and distribution of elements in fruiting bodies, from emergence to senescence, is essential as is standardization when choosing mushroom species as potential bioindicators and for monitoring purposes. We studied the effect of fruitbody developmental stage on the contents of the elements (Li, K, V, Cr, Mn, Mg, Co, Ni, Cu, Zn, As, Rb, Sr, Ag, Al, Cd, Sb, Cs, Ba, Pb, Tl and U) in the individual parts of the Amanita muscaria fruiting body. Elements such as K, Mg, Mn, Ni, Co, Cu, Zn and Se remained similar throughout all developmental stages studied, however for K, differences occurred in the values of caps and stipes, as expressed by the cap to stipe concentration quotient (index Q_C/S). The other elements quantified, i.e., Li, V, Cr, As, Rb, Sr, Ag, Al, Cd, Sb, Cs, Ba, Pb, Tl and U are considered as nonessential or toxic (with the exception of V in A. muscaria). Their accumulation in the fruiting bodies and their distribution between cap and stipe did not show a uniform pattern. Pb, Sb, Tl, Ba, Sr, Li, Rb and Cs decreased with increasing maturity of the fruitbodies, implying that translocation, distribution and accumulation in stipes and caps was not a continuous process, while V, Cr, As, Ag, Cd, and U remained at the same concentration, similarly to the essential elements. Our results for A. muscaria confirm that elemental distribution in different parts of fruiting bodies is variable for each element and may change during maturation. Soil properties, species specificity and the pattern of fruitbody development may all contribute to the various types of elemental distribution and suggest that the results for one species in one location may have only limited potential for generalization.

Arsenic speciation in mushrooms using dimensional chromatography coupled to ICP-MS detector

This study concerns total arsenic (TAs) and arsenic species determination in three species of mushrooms collected in Yunnan, China. The purpose of this study was to check concentration level of arsenic in Boletus edulis, Tricholoma matsutake and Suillellus luridus, estimate arsenic bioaccessibility and find out which arsenic species occur in mushrooms to assess if they may pose a threat to human health. An analytical methodology based on ion chromatography (IC) hyphenated to inductively coupled plasma mass spectrometry (ICP-MS) with dynamic reaction cell (DRC) and size exclusion chromatography (SEC) with UV-Vis detection and ICP-DRC-MS detection. Ultrasound assisted extraction (UAE), microwave assisted extraction (MAE) and enzymatic assisted extraction (EAE) were applied. Quantification of As species in extracts was performed by IC/ICP-DRC-MS in the first dimension. Slightly better extraction efficiencies were obtained for MAE (from 75% to 90%) then for UAE. EAE was used for estimation of bioaccessibility by application of a modified BARGE bioaccessibility method (UBM) for in vitro studies. Bioaccessibility values were in the ranges of 73%-102%, 74%-115% and 18%-87% for step 1 (S1), for step 2 (S2) and for step 3 (S3) of EAE, respectively. Extracts obtained after EAE were subjected to SEC-UV-Vis/ICP-DRC-MS analysis as the second dimension. The main signal was obtained in the area of a molecular mass of ∼5 kDa for all mushroom extracts. Monitoring of an ⁵⁰SO⁺ ion confirmed that this signal comes from As-protein. In sample of Boletus edulis additional signal occurred which is classified as unknown As-compound. Both signals require identification with another analytical technique.

Element distribution in fruiting bodies of Lactarius pubescens with focus on rare earth elements

During growth and senescence, fungal fruiting bodies accumulate essential and non-essential elements to different extent in their compartments. This study bases on a dataset of 32 basidiocarps of the ectomycorrhizal Lactarius pubescens sampled in a former U mining area. Statistical analyses were combined with rare earth element (REE, La-Lu) patterns to study the element distribution within sporocarp compartments and between three different age classes. For this purpose, fruiting bodies were separated into stipe, pileus trama, pileipelles and lamellae, dried and digested with HNO₃. While macronutrient (e.g. K, Mg, P, S) contents resemble those of a non-mining affected site, several elements (e.g. Co, Mn) were site-specifically taken up relative to elevated soil contents. With statistics, two main element distribution groups for L. pubescens were revealed: mainly essential (Cu, Mg, Mn, P, S, Zn, Cd, Co, Ni) and mainly non-essential elements (Al, Ca, Fe, Sr, U, REE). The highest REE contents were found in pileipelles and lamellae, corresponding to relatively small cell sizes. Stipes and pileus trama had low REE contents due to their function as transport systems. During growth, light REE (La-Nd) were strongly enriched in lamellae and pileipelles. Middle REE (Sm-Dy) enrichment was found both in soil and fungal biomass. Contents of nutrients decrease with age, while non-essential elements are enriched especially in pileipelles and lamellae. A weak positive Ce anomaly appeared in the bioavailable soil fraction and in the pileipelles of younger individuals. Substrate dependent uptake thus gets reduced with sporocarp senescence, possibly due to redistribution.

Bio-concentration potential and associations of heavy metals in Amanita muscaria (L.) Lam. from northern regions of Poland

Fruiting bodies of Amanita muscaria and topsoil beneath from six background areas in northern regions of Poland were investigated for the concentration levels of Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Rb, Sr, and Zn. In addition, the bioconcentration factors (BCF values) were studied for each of these metallic elements. Similar to studies from other basidiomycetes, A. muscaria showed species-specific affinities to some elements, resulting in their bioconcentration in mycelium and fruiting bodies. This mushroom growing in soils with different levels of the geogenic metallic elements (Ag, Al, Ba, Ca, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Rb, Sr, and Zn) showed signs of homeostatic accumulation in fruiting bodies of several of these elements, while Cd appeared to be accumulated at a rate dependent of the concentration level in the soil substrate. This species is an efficient bio-concentrator of K, Mg, Cd, Cu, Hg, Rb, and Zn and hence also contributes to the natural cycling of these metallic elements in forest ecosystems.

Evaluation of vulnerability of Suillus variegatus and Suillus granulatus mushrooms to sequester mercury in fruiting bodies

This work determined the mercury (Hg) contents and bioconcentration potential of two Suillus mushrooms, and the probable dietary intake of this element from a mushroom meal. The determination of total Hg content of fungal and soil samples was performed using cold-vapour atomic absorption spectroscopy by a direct sample thermal decomposition coupled with gold wool trap of Hg and its further desorption and quantitative measurement at a wavelength of 253.7 nm. The median values of Hg contents (mg kg(-1) dry biomass) in 213 specimens of S. variegatus from 12 background areas varied widely from 0.087 to 0.51 for caps and from 0.041 to 0.24 for stipes. In 52 specimens of S. granulatus, the Hg contents ranged from 0.30 to 0.41 for caps and from 0.058 to 0.14 for stipes. Both species could be classified as moderate accumulators of Hg and the median bioconcentration factor values ranged from 7.0 to 14 (caps) and 2.1 to 13 (stipes) for S. variegatus and 9.5 (caps) and 1.3 (stipes) for S. granulatus. The estimated intake rates of Hg with the consumption of 300-g caps were from 0.0026 to 0.015 per capita or from 0.000037 to 0.00022 mg kg(-1) body mass and this do not indicate any cause for concern associated with eating a meal once or more in a week during the mushrooming season.

Mercury bioaccumulation by Suillus bovinus mushroom and probable dietary intake with the mushroom meal

This paper reports the results of the study of the efficiency of accumulation and distribution of mercury (Hg) in the fruiting bodies of fungus Suillus bovinus and the probable dietary intake of Hg and the potential health risk. Fungal fruiting bodies and soil materials were collected from 13 background areas in the northern part of Poland between 1993 and 2013. Mercury in the caps of fruiting bodies varied from 0.10 ± 0.06 to 0.79 ± 0.40 mg kg(-1) dry biomass and in the stipes from 0.083 ± 0.028 to 0.51 ± 0.22 mg kg(-1) dry biomass. The mean values of cap to stipe Hg content quotient varied from 1.3 ± 0.2 to 2.6 ± 0.6. The Hg content in the upper 0-10 cm layer of soil substrate varied from 0.015 ± 0.004 to 0.031 ± 0.019 mg kg(-1) dry biomass. S. bovinus could be considered as an efficient accumulator of Hg, at least from low level polluted soils, and the values of Hg bioconcentration factor (BCF) varied from 6.4 ± 2.2 to 45 ± 20 for caps and from 3.8 ± 1.4 to 29 ± 11 for stipes. A conventional meal (300 g) portion of S. bovinus foraged from background areas provides Hg dose far below the provisionally tolerable weekly intake or recommended reference dose set for this element by authorities. An examination of published data on Hg in fruiting bodies of fungi genus Suillus showed low contamination of specimens foraged from background areas. Also reviewed are published data on Hg in fungi genus Suillus collected worldwide.

Accumulation and distribution of mercury in fruiting bodies by fungus Suillus luteus foraged in Poland, Belarus and Sweden

Presented in this paper is result of the study of the bioconcentration potential of mercury (Hg) by Suillus luteus mushroom collected from regions within Central, Eastern, and Northern regions of Europe. As determined by cold-vapor atomic absorption spectroscopy, the Hg content varied from 0.13 ± 0.05 to 0.33 ± 0.13 mg kg(-1) dry matter for caps and from 0.038 ± 0.014 to 0.095 ± 0.038 mg kg(-1) dry matter in stems. The Hg content of the soil substratum (0-10 cm layer) underneath the fruiting bodies showed generally low Hg concentrations that varied widely ranging from 0.0030 to 0.15 mg kg(-1) dry matter with mean values varying from 0.0078 ± 0.0035 to 0.053 ± 0.025 mg kg(-1) dry matter, which is below typical content in the Earth crust. The caps were observed to be on the richer in Hg than the stems at ratio between 1.8 ± 0.4 and 5.3 ± 2.6. The S. luteus mushroom showed moderate ability to accumulate Hg with bioconcentration factor (BCF) values ranging from 3.6 ± 1.3 to 42 ± 18. The consumption of fresh S. luteus mushroom in quantities up to 300 g week(-1) (assuming no Hg ingestion from other foods) from background areas in the Central, Eastern, and Northern part of Europe will not result in the intake of Hg exceeds the provisional weekly tolerance limit (PTWI) of 0.004 mg kg(-1) body mass.

Mercury in Orange Birch Bolete Leccinum versipelle and soil substratum: bioconcentration by mushroom and probable dietary intake by consumers

The aim of this study was to examine the contamination, accumulation, and distribution of mercury in fruiting bodies by Leccinum versipelle fungus collected from distant sites across Poland. Mercury was determined using validated method by cold-vapor atomic absorption spectroscopy after direct sample matrix combustion. A large set of data gained using 371 fruiting bodies and 204 soil samples revealed the susceptibility of L. versipelle to Hg contamination and permitted the estimation of probable intake of Hg contaminant by consumers foraging for this species. The range of median values of Hg determined in caps of L. versipelle was from 0.20 to 2.0 mg kg(-1) dry biomass, and the median for 19 localities was 0.65 mg kg(-1) dry biomass. The values of the Hg bioconcentration factor (BCF) determined for L. versipelle correlated negatively with Hg contents. Mercury in topsoil beneath L. versipelle ranged from 0.019 to 0.041 mg kg(-1) dry matter for less-contaminated locations (BCF of 17 to 65 for caps) and from 0.076 to 0.39 mg kg(-1) dry matter for more contaminated locations (BCF of 1.9 to 22). Fruiting bodies of L. versipelle collected in some regions of Poland if consumed in amount of 300 g in one meal in a week could provide Hg doses above the provisionally tolerable weekly intake (PTWI) value of 0.004 mg Hg kg(-1) body mass, while regular consumptions for most of the locations were below the limit even with more frequent consumption. Also summarized are available data on Hg for three species of fungi of genus Leccinum foraged in Europe.

Evaluation of the mercury contamination in mushrooms of genus Leccinum from two different regions of the world: Accumulation, distribution and probable dietary intake

This study focused on investigation of the accumulation and distribution of mercury (Hg) in mushrooms of the genus Leccinum that emerged on soils of totally different geochemical bedrock composition. Hg in 6 species from geographically diverse regions of the mercuriferous belt areas in Yunnan of SW China, and 8 species from the non-mercuriferous regions of Poland in Europe was measured. Also assessed was the probable dietary intake of Hg from consumption of Leccinum spp., which are traditional organic food items in SW China and Poland. The results showed that L. chromapes, L. extremiorientale, L. griseum and L. rugosicepes are good accumulators of Hg and the sequestered Hg in caps were up to 4.8, 3.5, 3.6 and 4.7 mg Hg kg(-1) dry matter respectively. Leccinum mushrooms from Poland also efficiently accumulated Hg with their average Hg content being an order of magnitude lower due to low concentrations of Hg in forest topsoil of Poland compared to the elevated contents in Yunnan. Consumption of Leccinum mushrooms with elevated Hg contents in Yunnan at rates of up to 300 g fresh product per week during the foraging season would not result in Hg intake that exceeds the provisional weekly tolerance limit of 0.004 mg kg(-1) body mass, assuming no Hg ingestion from other foods.

Distribution of mercury in Amanita fulva (Schaeff.) Secr. mushrooms: Accumulation, loss in cooking and dietary intake

Representative individual specimens and pooled samples of carpophores of edible wild-grown fungus Amanita fulva (Schaeff.) Secr. and forest topsoil layer (0-10 cm) beneath the carpophores were collected from 15 spatially distant places in Poland and examined for total Hg. The median values of Hg in soils for most of the sites were below 0.05 mgkg(-1) dry matter. The ability of fungus A. fulva to bioconcentrate Hg was low (BCF, bioconcentration factor values of 1.2-3.6 for caps and 0.66-1.7 for stipes) at five sites that showed Hg in soils ranging from 0.066 to 0.21 mgkg(-1) dry matter, while much higher bioconcentration (BCF of 11-25 for caps and 7.0-12 for stipes) were observed for less contaminated soils with Hg contents of 0.018-0.054mgkg(-1) dry matter. Differences were also observed in Hg contamination of A. fulva from spatially and distantly distributed sites, and the median values (mgkg(-1) dry matter) ranged from 0.13 to 0.67 for caps and from 0.065 to 0.34 for stipes, while 0.63mgkg(-1) dry matter was observed in a set of whole fruiting bodies. Boiling of fresh A. fulva for 10min reduced the Hg content by 10%. A meal of A. fulva containing 0.065mgkg(-1) of Hg in the fresh mushroom product will not result in exceeding the reference dose set for inorganic Hg and for majority of the sites assessed (>90%) intake was substantially lower than the reference dose or the provisional tolerable weekly intake of inorganic Hg.

Mercury contamination of fungi genus Xerocomus in the Yunnan province in China and the region of Europe

This article presents the results of the study on accumulation, distribution, contamination and probable dietary intake of total mercury (THg) in fruiting bodies of several species of Fungi genus Xerocomus, which emerged in the circum-Pacific mercuriferous belt region in southwestern China in Yunnan and beyond of the mercuriferous belts in the region of Europe. The mushrooms X. puniceus (Boletus amygdalinus), X. spadiceus (Boletus ferrugineus) and X. versicolor (X. rubellus) were from the Yunnan land, and X. badius (Boletus badius) was from the region of Europe in Belarus and X. badius, X. chrysenteron, X. ferrugineus, X. versicolor (X. rubellus) and X. subtomentosus from Poland. The THg in the fungal and soil materials was determined using validated method by cold-vapour atomic absorption spectroscopy. Estimated was also probable dietary intake and health risk from THg in Xerocomus spp. examined by consumers. The data showed that THg content of Xerocomus spp. emerged in the European localizations in Poland and Belarus is at an order of magnitude lower level than determined in samples from the Yunnan Province. A reason for an elevated content of THg in mushrooms from Yunnan can be related to abundance of Hg in the geochemical background of soils there. The assessed doses showed that a single meal composed of 300 g of fresh fruiting bodies of X. spadiceus from the Wuding localization in Yunnan in China if consumed once a week will provide THg at dose close to the provisional tolerable weekly intake (PTWI) value set for THg, while doses will be lower for all other localizations in Yunnan and Europe. In the Wuding localization in Yunnan a frequent consumption of X. spadiceus in volume exceeding 300 g of fresh fruiting bodies per week will provide THg at a dose exceeding the value of PTWI.

Distribution of mercury in Gypsy Cortinarius caperatus mushrooms from several populations: an efficient accumulator species and estimated intake of element

Mushroom Cortinarius caperatus is one of the several edible wild-grown species that are widely collected by fanciers. For specimens collected from 20 spatially and distantly distributed sites in Poland the median values of Hg contents of caps ranged from 0.81 to 2.4mgkg(-1) dry matter and in stipes they were 2.5-fold lower. C. caperatus efficiently accumulates Hg and the median values of the bioconcentration factor for caps range from 120 to 18 and for stipes from 47 to 7.3. This mushroom even when collected at background (uncontaminated) forested areas could be a source of elevated intake of Hg. The irregular consumption of the caps or whole fruiting bodies is not considered to pose a risk. Frequent eating of C. caperatus during the fruiting season by fanciers should be avoided because of possible health risk from Hg. Available data on Hg contents of C. caperatus from several places in Europe are also summarized.

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.

Mercury in the fairy-ring of Gymnopus erythropus (Pers.) and Marasmius dryophilus (Bull.) P. Karst. mushrooms from the Gongga Mountain, Eastern Tibetan Plateau

Gongga Mountain or Minya Konka, like the Himalayan Dimension Mountains, has its own microclimate and a 'circum-polar' climate and hence is sensitive to contamination by persistent pollutants that are trapped by cold temperature and wet precipitation. Elemental mercury (Hg) as vapour easy diffuses into the atmosphere and the rate of Hg deposition from global fallout is dependent on locally ambient temperature and precipitation. We investigated the accumulation and distribution of total Hg in two species of mushrooms, Gymnopus erythropus and Marasmius dryophilus, which grew on Gongga Mountain. The fruiting bodies were collected at a height of 2946m above see level. Both species efficiently accumulated Hg. The median values for caps of M. dryophilus and G. erythropus were 1.168 and 3.078, and for stipes 0.573 and 1.636mg/kg dry matter, respectively, and in the beneath litter and soil were 0.13 and 0.15mg/kg dry matter. The Hg contents of the caps of M. dryophilus and the beneath litter and soils from pristine Himalayan forest of 1.168, 0.132 and 0.116mg/kg dry matter (respectively) is high compared to values reported for similar species and soils from background areas in Poland -0.58-0.70 and 0.047-0.048mg/kg dry matter. The absence of industrial activities, urbanization and Hg ore deposits at Gongga Mountain suggests that long-range atmospheric transport and subsequent deposition is the major source of elevated Hg observed in the mushrooms, litter and surface layer of soils in the outskirts of Gongga Mountain maritime glacier that has a peak of 7556m above sea level.

Mercury in certain boletus mushrooms from Poland and Belarus

This paper reports the results of the study of Hg contents of four species of Boletus mushroom (Boletus reticulatus Schaeff. 1763, B. pinophilus Pilát & Dermek 1973, B. impolitus Fr. 1838 and B. luridus Schaeff. 1774) and the surface soils (0-10 cm layer, ∼100 g) samples beneath the mushrooms from ten forested areas in Poland and Belarus by cold-vapour atomic absorption spectroscopy. The ability of the species to bioconcentrate Hg was calculated (as the BCF) while Hg intakes from consumption of these mushroom species were also estimated. The median Hg content of the caps of the species varied between 0.38 and 4.7 mg kg(-1) dm; in stipes between 0.13 and 2.5 mg kg(-1) dm and in the mean Hg contents of soils varied from 0.020 ± 0.01 mg kg(-1) dm to 0.17 ± 0.10 mg kg(-1) dm which is considered as "background" Hg level. The median Hg content of caps of B. reticulatus and B. pinophilus were up to 4.7 and 3.6 mg kg(-1) dm, respectively, and they very efficiently bioaccumulate Hg with median BCF values of up to 130 for caps and 58 for stipes. The caps and stipes of these mushrooms if eaten will expose consumer to elevated dose of total Hg estimated at 1.4 mg for caps of Boletus reticulatus from the Kacze Łęgi site, which is a nature reserve area. Nevertheless, the occasional consumption of the valued B. reticulatus and B. pinophilus mushrooms maybe safe.

Mercury in the Grisette, Amanita vaginata Fr. and soil below the fruiting bodies

This study examined the mercury concentration in the Grisette Amanita vaginata Fr. and soil below the fruiting bodies collected between 2000 and 2008 from the wild at seven distant sites across Poland. The Hg content in samples was determined by cold atomic absorption method (CV-AAS) at a wavelength of 253.7 nm. Mean Hg contents varied from 0.096 ± 0.052 to 0.48 ± 0.13 mg kg(-1) dry matter (dm) in caps (range, 0.043-0.73 mg kg(-1)), from 0.047 ± 0.02 to 0.23 ± 0.07 mg kg(-1) dm (range, 0.028-0.47 mg kg(-1)) in stipes, and in underlying soil were from 0.035 ± 0.018 to 0.096 ± 0.036 mg kg(-1) dm (range, 0.017 to 0.16 mg kg(-1)). The median Qc/s values ranged from 1.2 to 2.2 (mean 1.2 ± 0.4 to 2.1 ± 0.5) indicating that Hg content in stipes was generally lower than in caps. This mushroom species has some potential to bioconcentrate Hg in the fruiting bodies, as the values of the bioconcentration factor (BCF) varied for the sites between 1.2 ± 0.6 to 11 ± 5 for caps and 0.61 ± 0.26 to 7.4 ± 3.9 for stipes. Also available literature data on Hg in A. vaginata are reviewed and discussed.

Bioconcentration potential and contamination with mercury of pantropical mushroom Macrocybe gigantea

The mushroom Macrocybe gigantea collected from the native stands in the Yunnan Province of China can be considered a species that efficiently bioconcentrates mercury (Hg) because the values of the bioconcentration factor (BCF) calculated for this element were well above unity, i.e., for caps, the BCF ranged from 4.8 to 24 and, for stipes, from 3.6 to 18. The Hg content of the composite samples of caps of the fruit bodies collected in the wild ranged from 0.48 to 1.78 mg kg(-1) dry matter and of stipes from 0.36 to 1.70 mg kg(-1) dry matter, whereas 0.37 and 0.25 mg kg(-1) dry matter were observed for farmed specimens. M. gigantea, because of a large biomass of the fruit bodies that emerge in a cluster, is an important food item in Yunnan, but knowledge on mineral composition and content of this species is largely absent. This study estimated the lifetime average daily dose intake of Hg through mushroom as well as the incremental lifetime cancer risk and non-cancer health hazard to consumers of this mushroom.

Clues for regulatory processes in fungal uptake and transfer of minerals to the basidiospore

Several fungal species are notorious for the preferential acquisition of toxicants such as AsCdHgPbU in their wild-grown basidiomes, but it is not known how, or whether at all, mineral uptake is regulated. In this study, basidiomes of Kuehneromyces mutabilis, Pleurotus ostreatus, and Hypholoma fasciculare were grown on Fagus sylvatica logs embedded in sand, uranium-overburden soil, and garden soil (SIO) at a lab scale to raise the accessible mineral resources 30 to >1,000 times over those available in the timber alone. Non-embedded logs and a field culture established on SIO served as controls. Concentrations of 22 minerals were determined by inductively coupled plasma mass spectrometry from microwave-digested samples of timber, soils, whole and dissected mushrooms, and basidiospores. It was the goal to determine whether mineral uptake rates vary simply with their concentration in the substrate or undergo selections which indicate the ability of metal sensing and optimizing/delimiting the quantity of (essential) elements on their passage from a substrate via basidiome to the basidiospores. It is shown that an underrepresented substrate mineral is up-concentrated to a more or less regulated and physiologically compatible mean, whereas a rising external mineral supply leads to uptake blockage by downregulation of the bioconcentration rate in the vicinity of an apparent mycelial saturation point. The resulting concentrations in whole K. mutabilis basidiomes of the essential metals, CaCoCuFeMgMn(Sr)Zn corresponded surprisingly with those in wheat grains which share the main metabolic pathways with fungi and whose metallome is believed to be out-regulated for an optimum and stress-free development. Concentrations of nonessential metals, too, fitted the range of those common crops, whereas KP reached the higher typical level of fungi. Minerals entering the lower stipe of the K. mutabilis basidiome were specifically enriched/diluted on a passage to the gills and once more abruptly up/down-concentrated at the basidium/sterigma/spore interface. Mineral concentrations of spores corresponded then again with those in wheat grains, with the metalloenzyme-linked CdCoCuFeMnNa(Ni) appearing moderately higher. It is concluded that the substrate/fungal interface may be the major site of metal sensing/selecting and uptake regulation. Concentration shifts obtained during the mineral transfer through the basidiome are then subject to ultimate corrections at the gill/spore interface.