Unraveling enigmatic arsenic speciation in mushrooms

Mushrooms play irreplaceable roles in nature as symbionts, saprotrophs, and parasites. Their fruit-bodies can accumulate high concentrations of arsenic (As) in a variety of chemical forms. However, our knowledge about the role of mushrooms in the biogeochemical cycle of As in forest ecosystems is still very limited. Given the widespread occurrence of methylated As species in a wide variety of mushrooms, it is likely that methylation of As is occurring directly in the macrofungi, but final proof is still missing. We will study the As speciation and transformations in mushrooms and connected environmental compartments in vivo, in vitro, and in silico. The complete As speciation (water- and lipid-soluble species, putative As binding peptides) will be studied in carefully selected mushrooms and correlated with their ecological strategies. In particular, we will study aspects such as the exchange and transformation of As compounds in mushroom parasites and their hosts and the impact of As-accumulating mushrooms on As mobility and speciation in underlying soils. To achieve this, arsenic species will be determined by high-performance liquid chromatography coupled to element and molecular mass spectrometry. The obtained results will be used as basis for molecular biology experiments. The involved multidisciplinary approach is expected to significantly improve understanding of the role of terrestrial fungi in As biogeochemistry in forest ecosystems and understanding of the arsenic biochemistry and biotransformation pathways in living systems.