The microbial degradation of chlorophenolic preservatives in spent,pressure-treated timber

The reduction of pentachlorophenol in treated timber, after inoculation with pentachlorophenol-degrading bacterial species,Rhodococcus chlorophenolicus andFlavobacterium sp., and the white-rot fungusPhanerochaete chrysosporium, was monitored in solid substrate systems and in liquid culture suspensions. In solid substrate systems there was no significant pentachlorophenol degradation by the bacterial species under a variety of conditions. Under similar conditions,Phanerochaete chrysosporium transformed over 80% of the starting concentration of 500 ppm to pentachloroanisole. In liquid culture suspensions however, mid-exponential phaseFlavobacterium sp. cells were able to degrade over 99% of the pentachlorophenol in sawdust and wood chips due to the extraction of PCP from the timber as a water soluble salt. There were however no significant changes in the chlorinated dioxin components during this treatment.Abbreviations ATTC American type culture collection - AWPA American Wood Preservers' Association - DSM Deutsche Sammlung für Mikroorganismen - GC/MS gas chromatograph/mass spectrometer - HpCDD heptachlorodibenzo-p-dioxin - HpCDF heptachlorodibenzofuran - HxCDD hexachlorodibenzo-p-dioxin - HxCDF hexachlorodibenzofuran - ¹³C-OCDD carbon 13-labelled octachlorodibenzo-p-dioxin - OCDD octachlorodibenzo-p-dioxin - OCDF octachlorodibenzofuran - PCDDs polychlorinated dibenzo-p-dioxins - PCDFs polychlorinated dibenzofurans - PCP pentachlorophenol - PnCDD pentachlorodibenzo-p-dioxin - PnCDF pentachlorodibenzofuran - TCDD tetrachlorodibenzo-p-dioxin - TCDF terachlorodibenzofuran - TeCP tetrachlorophenol - WHC water holding capacity - w/v weight for volume ratio