Changes in the activities of enzymes involved in the degradation of butylbenzyl phthalate by Pleurotus ostreatus.

Degradation of butylbenzyl phthalate (BBP) by the white rot fungus Pleurotus ostreatus and the activities of some degrading enzymes were examined in two different media containing 100 mg/l of the compound. P. ostreatus pregrown for 7 days in complex YMG medium was able to completely degrade BBP within an additional 24 h but degraded only 35 mg/l of BBP in 5 days of incubation in minimal medium. Fungal cell mass in the culture in YMG medium was higher in the presence than in the absence of BBP. The esterase activity of the fungal culture in YMG medium was higher than that in minimal medium and increased with the addition of BBP. On the contrary, laccase activity was higher in minimal medium and it did not increase upon the addition of BBP. General peroxidase activity increased for a few days after the addition of BBP to both media. The degradation of BBP and its metabolites by P. ostreatus thus may be attributed mostly to esterase rather than lignin-degrading laccase. In addition, the activities of the enzymes involved in BBP degradation and their changes varied significantly in the different media and culture conditions.

Biodegradation and saccharification of wood chips of Pinus strobus and Liriodendron tulipifera by white rot fungi.

Degradation and glucose production from wood chips of white pine (Pinus strobus) and tulip tree (Liriodendron tulipifera) by several white rot fungi were investigated. The highest weight losses from 4 g of wood chips of P. strobus and L. tulipifera by the fungal degradation on yeast extractmalt extract-glucose agar medium were 38% of Irpex lacteus and 93.7% of Trametes versicolor MrP 1 after 90 days, respectively. When 4 g of wood chips of P. strobus and L. tulipifera biodegraded for 30 days were treated with cellulase, glucose was recovered ot the highest values of 106 mg/g degraded wood by I. lacteus and 450 mg/g degraded wood by T. versicolor. The weight loss of 10 g of wood chip of L. tulipifera by T. versicolor on the nutrient non-added agar under the nonsterile conditions was 35% during 7 weeks of incubation, and the cumulative amount of glucose produced during this period was 239 mg without cellulase treatment. The activities of ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) of fungi tested did not show a high correlation with degradation of the wood chips and subsequent glucose formation. These results suggest that the selection of proper wood species and fungal strain and optimization of glucose recovery are all necessary for the fungal pretreatment of woody biomass as a carbon substrate.

Biodegradation of endocrine-disrupting phthalates by Pleurotus ostreatus.

Biodegradation of endocrine-disrupting phthalates [diethyl phthalate (DEP), dimethyl phthalate (DMP), butylbenzyl phthalate (BBP)] was investigated with 10 white rot fungi isolated in Korea. When the fungal mycelia were added together with 100 mg/l of phthalate into yeast extract-malt extract-glucose (YMG) medium, Pleurotus ostreatus, Irpex lacteus, Polyporus brumalis, Merulius tremellosus, Trametes versicolor, and T. versicolor MrP1 and MrP13 (transformant of the Mn-repressed peroxidase gene of T. versicolor) could remove almost all of the 3 kinds of phthalates within 12 days of incubation. When the phthalates were added to 5-day pregrown fungal cultures, most fungi except I. lacteus showed the increased removal of the phthalates compared with those of the nonpregrown cultures. In both culture conditions, P. ostreatus showed the highest degradation rates for the 3 phthalates tested. BBP was degraded with the highest rates among the 3 phthalates by all fungal strains. Only 14.9% of 100 mg/l BBP was degraded by the supernatant of P. ostreatus culture in YMG medium in 4 days of incubation, but the washed or homogenized mycelium of P. ostreatus could remove 100% of BBP within 2 days even in distilled water, indicating that the initial BBP biodegradation by P. ostreatus may be attributed to mycelium-associated enzymes rather than extracellular enzymes. The biodegradation rate of BBP by the immobilized cells of P. ostreatus was almost the same as that in the suspended culture. The estrogenic activity of 100 mg/l DMP decreased during biodegradation by P. ostreatus.