# Fungi and Arsenic: Tolerance and Bioaccumulation by Soil Saprotrophic Species
## 3 Results
### Evaluation of Element Concentrations in Fungal Biomass  
To evaluate the different accumulation of the elements in the fungal biomass of _A. spinosa_, _C. nanum_, _M. marquandii_, and _P. illacinum_ grown on MEA and CDA media (control) and on MEA and CDA media added with 10 mg/L, 20 mg/L and 50 mg/L of sodium arsenite, the concentration variability of As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Sb, Sn, and Sr was assessed (Supplementary Materials Table S1). Principal component analysis performed on the obtained data allowed us to cluster the samples (scores) according to the different accumulation of the elements (loadings) in the four tested strains in the different experimental conditions. Five significant components accounting for 71.47% were obtained (the scores and loadings are shown in Supplementary Materials Table S2); the variance explained by each component was 22.3%, 18.2%, 15.3%, 8.9%, and 6.7%. The first component (PC1), which explains 22.3% of the total variance, well separated the samples of the fungal species in which higher concentrations of As were accumulated from the others. On the other hand, PC2, which explains 18.2% of the total variance, well clustered the elements, depending on their concentration variability among the samples and separated the samples of the fungal strains grown on MEA medium from those grown on the CDA medium. Therefore, PC1 and PC2, which explain 40.5% of the total variance, are represented in the score plot and loading plot of Figure 1.  
Figure 1: Score plot and loading plot of PC1 and PC2 obtained by the Principal Component Analysis (PCA) performed on the element concentrations determined in the fungal biomass of the tested species _A. spinosa_ (As), _C. nanum_ (Cn), _M. marquandii_ (Mm), and _P. illacinum_ (PI) grown on MEA and CDA media (C) and on MEA and CDA media added with 10 mg/L, 20 mg/L and 50 mg/L of sodium arsenite, respectively. Sample labels: AsCMEA, As10 MEA, As20 MEA, As50 MEA, AsCCDA, As10 CDA, As20 CDA, As50 CDA (black color); MmCMEA, Mm10 MEA, Mm20 MEA, Mm50 MEA, Mm10 CDA, Mm10 CDA, Mm20 CDA, Mm50 CDA (blue color); PICMEA, PI10 MEA, PI20 MEA, PI50 MEA, PI50 MEA, PI10 CDA, PI10 CDA, PI20 CDA, PI50 CDA (green color); CnCMEA, Cn10 MEA, Cn20 MEA, Cn50 MEA, CnCCDA, Cn10 CDA, Cn20 CDA, Cn50 CDA (red color). In the score plot in Figure 1, we can observe that all of the samples of the fungal species grown on CDA medium were separately clustered from the samples grown on MEA due to their different variability in element concentrations. In fact, the fungal strains grown on CDA showed higher concentrations (Supplementary Materials Table S1) of Fe, K, Mg, Na, P, and S (because of the higher accessibility of nutrients contained in CDA medium; composition is reported in Section 2.1), which are plotted on the left upper part of the corresponding loading plot. Among the four species, _A. spinosa_ samples were separately clustered from the others, this can reasonably be ascribed to the different variability in concentrations of Ca, Co, Fe, Mg, P, and Sr, plotted on the left part of the corresponding loading plot. Indeed, as can be seen from Supplementary Materials Table S1, _A. spinosa_ was found to be the strain with the highest concentrations of Ca, Co, Fe, Mg, P, and Sr. On the other hand, _P. lilacinum_ appeared to accumulate the highest concentration of K, and C. _mann_ and _M. marquandii_ were found to be the species with the highest concentrations of Na and S.  
Cadmium, Cu, Cr, Mn, Ni, Pb, and Sn were plotted on the central part of the loading plot, since their concentration values had poor variability among the samples. Therefore, As addition in both culture media did not appear to have affected the accumulation of these elements by the different fungal species.