612 Venturella et al.: Journal of AOAC International Vol. 97, No. 2, 2014 RESIDUES AND TRACE ELEMENTS
The Mineral Contents of Some Boletaceae Species from Sicily (Southern Italy) Giuseppe Venturella, Maria Letizia Gargano, Riccardo Compagno, and Alessandro Saitta
University of Palermo, Department of Agricultural and Forest Sciences, Viale delle Scienze, I-90128 Palermo, Italy Maria Grazia Alaimo University of Palermo, Department of Earth and Sea Science, Via Archirafi 22, I-90123 Palermo, Italy
Data on the accumulation of metals in wild edible and inedible macrofungi of the Boletaceae family are discussed here and compared with data reported in literature from northern Italy and other European countries, as well as from China, Brazil, and Africa. The results show a significant difference in the values detected in Sicilian fungi compared to those reported in the literature.
M
acrofungi can accumulate high concentrations of heavy metals (1). Rühling et al. (2) demonstrated how individual fungal species were affected by metal pollution, and how macrofungi and microfungi differ in their response to metal pollution. The accumulation of several heavy metals and lanthanides in Amanita flavorubescens G.F. Atk.; A. rubescens Pers. var. rubescens; and Russula pectinatoides Peck was reported by Aruguete et al. (3). Studies on the effects and responses to heavy metal exposure in macromycetes have focused on edible and poisonous saprophytic and ectomycorrhizal fungi such as Pleurotus ostreatus (Jacq.) P. Kumm. (4), Suillus luteus (L.) Roussel (5), Paxillus involutus (Batsch) Fr. (6, 7), and Hebeloma crustuliniforme (Bull.) Quél. (8). Allen and Steinnes (9) and Collin-Hansen et al. (10, 11) reported high concentrations of Cd, Zn, Hg, and Cu in Boletus edulis Bull. basidiomata growing in both uncontaminated and polluted areas. The contents of several mineral elements in higher fungi have been reported, including metals as well as nonmetallic elements, by Vetter (12–15). An investigation of heavy metal levels in edible, inedible, and poisonous macrofungi collected in Turkey was carried out by Isildak (16), Yilmaz et al. (17), Yesil et al. (18, 19), and Durkan et al. (20). Aloupi et al. (21) published an assessment of the Cd, Cu, Cr, Fe, Mn, Ni, Pb, and Zn contents in wild edible mushrooms from the island of Lesvos (Greece). Contributions to the knowledge of the heavy metal content in edible mushrooms from northern Italy were published by Cocchi et al. (22) and Cenci et al. (23). The lack of appropriate studies in the southernmost regions of Italy stimulated our interest in analyzing the metal content of some wild edible, inedible, and poisonous macrofungi growing in Sicily (southern Italy). Received June 25, 2012. Accepted by AK August 20, 2012. Corresponding author’s e-mail:
[email protected] DOI: 10.5740/jaoacint.12-260
Experimental Sampling Nine basidiomata of seven wild mushrooms species belonging to the family Boletaceae Chevall., i.e., B. reticulatus Schaeff., B. impolitus Fr., B. lupinus Fr., B. queletii Schulzer (from two different locations), B. rhodoxanthus (Krombh.) Kallenb., B. satanas Lenz, and Leccinellum lepidum (H. Bouchet ex Essette) Bresinsky & Manfr. Binder (from two different locations) were collected in broad-leaved and conifer forest ecosystems. The mushroom samples were cleaned of forest debris (without washing) with a brush, transported to the laboratory, and kept at –4°C for no more than 24 h prior to sample preparation. Identification was carried out using fresh basidiomata, and samples of each species were assayed individually. Every sample comprised a complete basidiomata (cap, hymenium, and stipe). The macromorphological characteristics were evaluated with a Leica (Leica Microsystems srl, Via Ettore Bugatti 12, Milano, Italy) MS5 binocular microscope as follows: pileus (size, shape, color, surface, shape, and surface of margin, and flesh); characteristics of tubules and pores; stipe (size, attachment, shape, surface, color and color changes, consistency, and flesh); growth habit; basidiomata attachment to the substrate; and spore colors. The microscopic features (spores, cystidia, basidia, basidioles, hyphal systems, hyphal walls, septations, hyphal branching, hyphal inflations, and specialized hypha) were evaluated with a Leica DLMB microscope using tap water and chemical reagents such as 95% ethanol, 3% potassium hydroxide (KOH) or 5–10% ammonium hydroxide (NH4OH), Teepol, acetocarmine, chloral hydrate, Congo red, cotton blue, cresyl blue, fuchsin, guaiac, hydrochloric acid, Melzer’s reagent, methylene blue, sodium hydroxide (NaOH), sulfobenzaldehyde, and sulfuric acid. The species were identified according to Breitenbach and Kränzlin (24) (1991). The herbarium specimens were prepared in a hamper ventilator and kept in the Herbarium Mediterraneum Panormitanum. The scientific binomials and trinomials of the recorded taxa are according to the www.indexfungorum.org/ Names/Names.asp website. The collection sites and sample code are reported in Figure 1 and listed below: Province of Palermo.—Monte Pizzuta, carbonate rocks, samples code A1, A3; Bosco Pomieri, carbonate rocks, samples code A2; Piano Torre, carbonate rocks, samples code A4; Piano della Madonna, carbonate rocks, samples code A9. Province of Agrigento.—Pizzo Mondello, clay, samples code A5. Province of Messina.—Passo Taverna, flyschoid, samples code A6, A7; Bosco di Scavioli, flyschoid, samples code A8.
Venturella et al.: Journal of AOAC International Vol. 97, No. 2, 2014 613
Figure 1. Study area with sampling sites.
The Table 1 header shows the following items for each element: the unit of measurement, the instrumental detection limit, coal ashes, and method blank. In addition, in the body of Table 1 the sample code for each investigated mushroom, the average value of each element in the topsoil, the slates, the carbonates in the clay, the concentrations of the elements for each sample, the accumulation factor of the element (per sample) for the various lithological types, and the SD are reported. Analysis The analysis of mushrooms was carried out and certified for QC by Activation Laboratories LTD (Ontario, Canada) belonging to the group Actlabs. The analytical package used was via HNO3–H2O2 digestion under temperature-controllable conditions and inductively coupled plasma/MS. The nomenclature adopted follows that of the International Union of Pure and Applied Chemistry. Quality Control (QC) According to internal QC procedures for the collection and treatment of plant materials, the contaminated samples (by soil, dust, etc.) were washed in tap water for a minimum amount (30 s) of time. Each sample was analyzed in three replicates, and the results were reported as mean values ± SD. Results and Discussion Our data (Table 1) could be partially compared with the results obtained for edible mushrooms collected in northern Italy by Cocchi et al. (22). Those authors analyzed the As, Cd, Hg, Pb, and Se contents of 57 mushrooms, including five Boletus species. In particular, they reported a heavy metals content for Boletus reticulatus Schaeff. [sub: B. aestivalis (Paulet) Fr.] that was definitely lower than the value determined for the same species collected in Sicily. The content of Se is close to the value reported for B. edulis Bull. and lower than that of B. pinophilous Pilát & Dermek. In the Sicilian samples of B. reticulatus, the Cd content is higher than other Boletus species, while Pb content is considerably higher than that reported for all mushrooms species analyzed by Cocchi et al. (22). The Pb content of mushroom species from northern Italy ranges from 0.54 mg/kg in B. chrysenteron Bull.
[sub: Xerocomus chrysenteron (Bull.) Quél.] to 10.6 mg/kg in Lycoperdon utriforme Bull. [sub: Calvatia utriformis (Bull.) Jaaap]. In contrast, the Pb values in our investigated mushrooms are never less than 11.6 ppm (B. satanas Lenz), reaching the highest value of 50.7 ppm in B. reticulatus. Cenci et al. (23) observed a superposition of concentration values for Al, Cr, Ni, Pb, Cu, Hg, Zn, Cd, and As in B. edulis collected in northern Italy and Finland. Comparing our data with the results shown by Konuk et al. (25) on the concentrations of toxic and essential elements of several wild edible mushrooms from Turkey, including two species belonging to the family Boletaceae, i.e., S. luteus (L.) Roussel and S. sibiricus (Singer) Singer, only the Ca, Fe, K, and Mg contents are lower in the fungi collected in Sicily. With the exception of B. queletii, the Na values are usually higher in the fungi collected in Turkey than those reported in our investigation. Significant differences in the values of Cd, Cu, Fe, Mn, and Zn emerge from the study of Blanuša et al. (26). The Cd content in B. queletii collected in Sicily is higher than that of the Croatian species, quite similar in that of B. reticulatus [sub: B. aestivalis] and lower in that of B. impolitus, B. rhodoxanthus, and B. satanas. The values of Cu, Mn, and Zn reported for the boletes of Croatia are definitively lower than those detected in the Sicilian fungi. In contrast, the values of Fe found in mushrooms collected in Croatia are much higher than those of the boletes harvested in Sicily. The values of Cd, Cu, Mn, and Zn in L. lepidum are lower in samples collected in Croatia, with the exception of Fe whose values are higher in fungi from Sicily. Based on the data reported by Yamaç et al. (27) for certain edible mushrooms from Central Anatolia (Turkey), we notice that the values of Fe are also higher in Turkey than those detected in Sicily. The values of Cr detected in S. bovinus (Pers.) Roussel are similar to those observed in B. queletii from Sicily, and those of B. chrysenteron practically coincide with those found in samples of B. lupinus collected in Sicily. Some correspondence was also noted between the values of Ni detected in Sicily for B. queletii, B. lupinus, and B. rhodoxanthus and those of the members of Boletaceae analyzed by Yamaç et al. (27). The values of Fe detected in mushrooms collected in Sicily are lower, even when compared with the content reported by Ita et al. (28, 29) for other basidiomycetes of the Niger Delta region. The contents of Cd, Cr, Cu, Pb, and Zn found in the species of the Boletaceae family from Sicily are much higher than those reported by Çayir et al. (30) for some species of the family of Russulaceae collected in Turkey. The content of Cd reported by Sha et al. (31) for L. griseum (Quél.) Bresinsky & Manfr. Binder [sub: B. griseus (Quél.) Sacc. & D. Sacc.] specimens collected in the city of Xichang (People’s Republic of China) is higher than that seen in boletes harvested in Sicily. By comparing the concentration of certain trace elements present in some of the most common edible mushrooms marketed in Brazil (32), it can be seen that the values of Zn in the Sicilian mushrooms are relatively rather high, while the K, Na, and Fe values are extremely low. Accumulation Factor Assuming that the soils of Sicily are mainly developed on carbonate sedimentary, clay, and flyscioid substrata, the concentrations of metals in mushrooms were related to the
614 Venturella et al.: Journal of AOAC International Vol. 97, No. 2, 2014 Table 1. Concentrations of metals in different species of Boletaceae Unit symbol, ppm
C.E.M.
Li
Na
K
Detection limit = 0.5 Coal ash std-2 meas = — Coal ash std-2 cert = — Method blank =
