Poster: Phytoremediation

Abs # 977: Glucosylation of Bisphenol A in Tobacco Cells

Presenter:	Nakajima, Nobuyoshi , naka-320@nies.go.jp
Authors	Nakajima, Nobuyoshi  (A)   Ohshima, Yukiko  (A)   Nagano, Kimiyo  (A)   Serizawa, Shigeko  (A)   Edmonds, John S (A)   Tamaoki, Masanori  (A)   Kubo, Akihiro  (A)   Aono, Mitsuko  (A)   Saji, Hikaru  (A)   Morita, Masatoshi  (A)
Affiliations:	(A): National Institute for Environmental Studies

Bisphenol A (BPA) is a potential endocrine disrupter, used as a stabilizer for many types of plastics. Annual world production of this compound has been estimated at more than 500,000 tones, therefore it has recently been a cause for anxiety because of the environmental release of BPA. Plants have been considered as suitable agents for the bioremediation of the compounds. However, the ability of plant cells to take up and metabolize BPA has not been investigated. In this study, we exposed a culture of tobacco BY-2 cells to BPA and studied the ability of the cells to take up and metabolize the compound. The chemical structure of its metabolites was also investigated. The concentration of BPA in the culture medium decreased rapidly and became undetectable at 2.5 h after the application. Four metabolites of BPA were observed in a methanol extract of the cells when the culture was supplemented with ¹⁴C-BPA. The most abundant metabolite was determined to be BPA-o-b-D-glucopyranoside (BPAG). When ¹⁴C-BPA was administrated to tobacco seedlings (Xanthi NC) from their roots, radioactivity was incorporated to BPAG and 3 unidentified metabolites. These metabolites were accumulated in the leaves 4 h-exposure, indicating that tobacco seedlings absorbed BPA through their root systems, metabolized to its b-glucoside and translocated the metabolites to their leaves (Plant Cell Physiol. 2002, 43: 1036-1042). We identified BPA specific glucosyltransferase (BGT) activity in cell-free extract of both tobacco suspension cultured cells and seedlings. Km for BPA was 82mM. Specific activity in the leaves was 4 fold higher than that in the roots. Our results indicated that tobacco plants have BGT and leaf tissue may be mainly responsible for the b-glucosylation of BPA.