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Applied and Environmental Microbiology, October 2000, p. 4205-4211, Vol. 66, No. 10
Department of Biochemistry and Microbiology,
Cook College, Rutgers University, New Brunswick, New Jersey
08903-0231,1 and Marine Biotechnology
Institute, Kamaishi Laboratories, 3-75-1 Heita, Kamaishi City,
Iwate 026-0001, Japan2
Received 6 April 2000/Accepted 6 July 2000
A microbial consortium which rapidly mineralized the
environmentally persistent pollutant benzo[a]pyrene was
recovered from soil. The consortium cometabolically converted
[7-14C]benzo[a]pyrene to
14CO2 when it was grown on diesel fuel, and the
extent of benzo[a]pyrene mineralization was dependent on
both diesel fuel and benzo[a]pyrene concentrations.
Addition of diesel fuel at concentrations ranging from 0.007 to 0.2%
(wt/vol) stimulated the mineralization of 10 mg of
benzo[a]pyrene per liter 33 to 65% during a 2-week
incubation period. When the benzo[a]pyrene concentration
was 10 to 100 mg liter
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Rapid Mineralization of Benzo[a]pyrene
by a Microbial Consortium Growing on Diesel Fuel
1 and the diesel fuel concentration
was 0.1% (wt/vol), an inoculum containing 1 mg of cell protein per
liter (small inoculum) resulted in mineralization of up to 17.2 mg of
benzo[a]pyrene per liter in 16 days. This corresponded to
35% of the added radiolabel when the concentration of
benzo[a]pyrene was 50 mg liter
1. A
radiocarbon mass balance analysis recovered 25% of the added benzo[a]pyrene solubilized in the culture suspension
prior to mineralization. Populations growing on diesel fuel most likely promoted emulsification of benzo[a]pyrene through the
production of surface-active compounds. The consortium was also
analyzed by PCR-denaturing gradient gel electrophoresis of 16S rRNA
gene fragments, and 12 dominant bands, representing different sequence types, were detected during a 19-day incubation period. The onset of
benzo[a]pyrene mineralization was compared to changes in
the consortium community structure and was found to correlate with the
emergence of at least four sequence types. DNA from 10 sequence types
were successfully purified and sequenced, and that data revealed that
eight of the consortium members were related to the class
Proteobacteria but that the consortium also included members which were related to the genera Mycobacterium and
Sphingobacterium.
*
Corresponding author. Mailing address: Marine
Biotechnology Institute, 3-75-1 Heita, Kamaishi City, Iwate, 026-0001, Japan. Phone: 81-193-26-5781. Fax: 81-193-26-6584. E-mail:
robert.kanaly{at}kamaishi.mbio.co.jp.
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