Affiliation:
1. Division of Microbiology, Department of Applied Chemistry and Microbiology, University of Helsinki, FIN-00014 Helsinki, Finland
2. Unit of Environmental Biotechnology, International Graduate School Zittau, D-02763 Zittau, Germany
Abstract
ABSTRACT
The litter-decomposing basidiomycete
Stropharia coronilla
, which preferably colonizes grasslands, was found to be capable of metabolizing and mineralizing benzo[
a
]pyrene (BaP) in liquid culture. Manganese(II) ions (Mn
2+
) supplied at a concentration of 200 μM stimulated considerably both the conversion and the mineralization of BaP; the fungus metabolized and mineralized about four and twelve times, respectively, more of the BaP in the presence of supplemental Mn
2+
than in the basal medium. This stimulating effect could be attributed to the ligninolytic enzyme manganese peroxidase (MnP), whose activity increased after the addition of Mn
2+
. Crude and purified MnP from
S. coronilla
oxidized BaP efficiently in a cell-free reaction mixture (in vitro), a process which was enhanced by the surfactant Tween 80. Thus, 100 mg of BaP liter
−1
was converted in an in vitro reaction solution containing 1 U of MnP ml
−1
within 24 h. A clear indication was found that BaP-1,6-quinone was formed as a transient metabolite, which disappeared over the further course of the reaction. The treatment of a mixture of 16 different polycyclic aromatic hydrocarbons (PAHs) selected by the U.S. Environmental Protection Agency as model standards for PAH analysis (total concentration, 320 mg liter
−1
) with MnP resulted in concentration decreases of 10 to 100% for the individual compounds, and again the stimulating effect of Tween 80 was observed. Probably due to their lower ionization potentials, poorly bioavailable, high-molecular-mass PAHs such as BaP, benzo(
g
,
h
,
i
)perylene, and indeno(1,2,3-
c
,
d
)pyrene were converted to larger extents than low-molecular-mass ones (e.g., phenanthrene and fluoranthene).
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
80 articles.
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