Rapid copper transfer and precipitation by wood-rotting fungi can effect copper removal from copper sulfate-treated wood blocks during solid-state fungal treatment

Copper sulfate (CuSO4)-treated Japanese cedar (Cryptomeria japonica) blocks were cultivated with copper-tolerant wood-rotting fungi, either Fomitopsis palustris TYP-0507 or Antrodia xantha Shiga-1F. After 2 weeks, mycelia of both species had covered the blocks, but wood weight loss was not observed. At that time, oxalate accumulations were 21% (E palustris) and 47% (A. xantha) of their maxima after 6 weeks. Within 2 weeks, the natural copper oxalate complex moolooite appeared at the interface between the wood surface and fungal mat of both species. In addition, the copper content in E palustris mycelia located far from the CuSO4-treated wood block was at least 5.5 times greater than that in mycelia on untreated controls. By brushing off the moolooite and mycelia, 42.9% (E palustris) and 34.7% (A. xantha) of the original copper was removed within 2 weeks. The results showed that both species transferred copper from inside the wood blocks and precipitated some of it as moolooite before significant wood decay was observed. Furthermore, E palustris transferred copper far from the wood blocks, probably through the hyphae. This rapid fungal transfer and precipitation of copper could provide a practical method for the bioremediation of CCA-treated wood. (C) 2014 Elsevier Ltd. All rights reserved.