Enhancement of pyrene mineralization in soil by wood-decaying fungi

Abstract

The mineralization of [14C]pyrene in sterilized and non-sterile soil was investigated using the wood-decaying fungi Kuehneromyces mutabilis and Agrocybe aegerita in a period of 63 days. In sterilized soil 5.1% and 1.5% of the pyrene was mineralized to 14CO2 by K. mutabilis and by A. aegerita, respectively. In non-sterile soil, 27.3% of pyrene was mineralized by indigenous soil microflora including a Mycobacterium gilvum strain. During soil inoculation with fungi the mineralization was higher (47.7% for K. mutabilis and 38.5% for A. aegerita). For a mass balance analysis the soil was extracted with toluene and methanolic KOH (humic acid extraction). Considering the sum of mineralization and formation of bound residues (non-extractable radioactivity), about 50% (sterilized soil) and 75% (non-sterile soil) of pyrene were eliminated by K. mutabilis. In comparison with indigenous soil microflora, K. mutabilis enhanced pyrene elimination up to 42%.