In order to establish whether patulin-degrading activity was
inducible and determine its localization, R. paludigenum (10 7
cells/ml) was incubated in pure NYDB (Sample 1) and NYDB con-
taining 10 l g/l patulin (Sample 2) at 28 ?C with shaking
(150 rpm) for 48 h. The supernatant and the cells were separated
by centrifugation and the supernatant from Sample 1 and Sample
2 were marked as S and S-pat, respectively. A small portion of S-
pat was analyzed by HPLC to confirm that patulin disappeared
completely. The cells were washed with phosphate buffer
(50 mM, pH 7.0) three times. Three grams of wet cells were quickly
ground with quartz sand and liquid nitrogen and suspended in
7 ml phosphate buffer. The samples were centrifuged at 4 ?C at
13,000g for 10 min and the supernatant was collected. The intra-
cellular protein solutions made from Sample 1 and Sample 2 were
marked as I and I-pat, respectively. Fifteen micrograms of patulin
was added to 5 ml S, S-pat, I, and I-pat at 25 ?C and the patulin con-
centrations were determined after 24 h.