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TECHNICAL REPORTS

Bioremediation and Biodegradation

Fungal Inoculum Properties: Extracellular Enzyme Expression and Pentachlorophenol Removal in Highly Contaminated Field Soils

^a Environment and Risk Management Group, The Horticulture and Food Research Inst. of New Zealand Ltd. (HortResearch), P.O. Box 51, Lincoln, New Zealand
^b Quality Systems, HortResearch, Ruakura, Private Bag 3123, Hamilton, New Zealand
^c Centre for Soil and Environmental Quality, P.O. Box 94, Lincoln Univ., Canterbury, New Zealand. Technology New Zealand Enterprise Scholarship No LINX03008

^* Corresponding author (mwalter{at}hortresearch.co.nz).

Received for publication March 25, 2007. This study was conducted to improve the pentachlorophenol (PCP) bioremediation ability of white-rot fungi in highly contaminated field soils by manipulating bioaugmentation variables. These were the dry weight percentage of fungal inoculum addition (31–175 g kg^–1), PCP concentration (100–2137 mg kg^–1 PCP), fungal inoculum formulation, and time (1–7 wk). Five fungal isolates were used: the New Zealand isolates Trametes versicolor (L.: Fr.) HR131 and Trametes sp. HR577; the North American isolates Phanerochaete chrysosporium Burds. (two isolates) and Phanerochaete sordida (Karst.) Erikss. & Ryv. Pentachlorophenol removal, manganese peroxidase, and laccase activity, and the formation of chloroanisoles in the contaminated field soils were measured. The majority of PCP removed by the Trametes isolates was in the first week after bioaugmentation. The maximum PCP removal by the fungi varied from 50 to 65% from a 1065 mg kg^–1 PCP contaminated field soil. Pentachlorophenol was preferentially converted to pentachloroanisole (PCA) by the Phanerochaete isolates (>60%), while 2 to 9% of the PCP removed by two Trametes isolates was converted to PCA. A pH increase was measured following bioaugmentation that was dependent on PCP concentration, fungal inoculum addition, and formulation. This, together with rapid initial PCP removal, possibly changed the bioavailability of the remaining PCP to the fungi and significantly decreased the sequestering of PCP in the contaminated field soils. The research supports the conclusion that New Zealand Trametes spp. can rapidly remove PCP in contaminated field soils. Bioavailability and extractability of PCP in the contaminated field soil may significantly increase after bioaugmentation.

Abbreviations: C/N, carbon to nitrogen ratio • ECD, electron capture detector • F2, Monterey pine sawdust–cornmeal starch formulation • F8, Monterey pine (Pinus radiata D. Don) sawdust–kibbled rye–CaCO₃ formulation • F15, Douglas fir [Pseudotsuga menziesii Mirbel (Franco)] sawdust–corn grits formulation • GC, gas chromatography • IANZ, International Accreditation New Zealand • MnP, manganese peroxidase • MS, mass spectroscopy • LSD, least significant difference • NTP, National Toxicology Program • PCA, pentachloroanisole • PCP, pentachlorophenol • REML, restricted maximum likelihood • SAFI, co-substrate amendment and fungal inocula • SED, standard error of difference in means • U, one international unit of enzyme