Compared to yeast esterase, fungal cutinase degraded butyl benzyl phthalate (BBP) far more efficiently; i.e., almost 60% of the BBP disappeared within 7.5 h. Also, the final chemical composition significantly depended on the enzyme used. Toxicity monitoring using bioluminescent bacteria showed that butyl methyl phthalate, a major product of degradation by esterase, was an oxidative toxic hazard.Phthalates are plasticizers used in the manufacture of polyvinyl chloride and often in paints, lacquers, and cosmetics (18,26,31). Phthalates found in sediment, water, and air (13) have also been detected in foods, as they can migrate out of food packaging materials (29,36). n-Butyl benzyl phthalate (BBP) is a phthalic ester in papers and paperboards used as packaging materials for aqueous, fatty, and dry foods (19,37). BBP exerted estrogenic activities in several in vitro tests (2,18,20,43). During the past 10 years, there have been a series of reports on the developmental toxicity of BBP in rats (1,11,12,39), and the teratogenic effects have also been observed in mice and chicks (4, 32).Cutinase, a hydrolytic enzyme that degrades cutin (a polyester consisting of hydroxy and epoxy fatty acids, usually with n-C 16 and n-C 18 of higher plants), can, unlike other lipases, show enzymatic activity without interfacial activation. Some microorganisms such as Fusarium oxysporum f. sp. pisi live on cutin as their sole carbon source producing extracellular cutinases, and several bacterial cutinases (Pseudomonas putida, Pseudomonas mendocina, and Corynebacterium spp.) have been isolated and characterized (8,21,23,25,30,34,35). These enzymes have been largely exploited for esterification and transesterification in chemical synthesis (16) and have also been applied in the composition of laundry or dishwashing detergent (14,28,38). Other potential uses for cutinase include its application in the oleochemistry industry (6) and in the degradation of plastic (22).In the present study, we investigated the efficacies of fungal cutinase and yeast esterase in the degradation of BBP. During the enzymatic degradation of BBP, time-course compositional changes of several BBP-derived compounds were monitored. The cellular toxicity of degradation products was also measured by using various bioluminescent bacteria.Enzymatic degradation of BBP by cutinase and esterase. Purified cutinase from F. oxysporum f. sp. pisi (kindly provided by C. M. J. Sagt, Utrecht University, Utrecht, The Netherlands) and commercial Candida cylindracea esterase (Boehringer Mannheim GmbH, Mannheim, Germany) were dissolved in Tris-HCl buffer (10 mM, pH 8.0), and the enzyme concentration was adjusted to 10 or 100 mg liter Ϫ1 . The enzymatic degradation of BBP (98% purity; Aldrich, Milwaukee, Wisc.) was begun by adding 50 l of the concentrated BBP solution (500 g liter Ϫ1 in pure methanol [99.9%; Merck, Darmstadt, Germany]) to 50 ml of the enzyme solution described above in a 250-ml flask and was continued for 3 days in the dark in a shaking incubator (30°C, 200 rpm).Analyses...