Towards optimisation of white-rot fungi bioremediation
Thesis DisciplineEnvironmental Sciences
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
New Zealand has a large number (approx. 8000) of sites contaminated by persistent chemicals, of which approximately 10% arecontaminated with pentachlorophenol (PCP) aa a legacy of former timber treatment sites. The fungicide PCP was used extensively by the forestry industry from the late 1940s to prevent sapstaining of wood. New Zealand was a heavy user of industrial grade PCP because of the predominance of radiata pine (Pinus radiata) which is a soft timber and more susceptible than most tree species to sapstain fungi. International research has shown that soils contaminated by such xenobiotics may be ameliorated using white-rot fungi. To avoid the uncertainties associated with the release of foreign organisms into the New Zealand environment, as legislated by the Hazard Substances and New Organisms Act (HSNO) and governed by the Environmental Risk Management Authority (ERMA), a national research initiative was undertaken in 1996 to study the potential of New Zealand native white-rot fungi for bioremediation. Native white-rot isolates were (1) collected (bioprospecting), (2) selected for their ability to degrade xenobiotics - in the initial phase using PCP as the model compound and (3) studied for their mechanisms and pathways of degradation. Organic waste materials were also evaluated for their suitability to serve as a carrier for fungal augmentation to polluted soil. This PhD study formed part of this larger national research programme, with very close interaction between the different researchers and research activities. The aim of this thesis was to optimise white-rot bioremediation of New Zealand isolates. The work described here was led by me, and the principal results are mine. Selected organisms were evaluated for PCP loss and breakdown in soil. Soil limiting factors (such as soil type, moisture, temperature, pollutant concentration) affecting colonisation of augmented isolates were identified. These laboratory results then were transferred into the field and PCP degradation studied using proto-type biopiles.