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Applied and Environmental Microbiology, May 2001, p. 2222-2229, Vol. 67, No. 5
Department of Biological Sciences, University
of Cincinnati, Cincinnati, Ohio 45221-0006
Received 18 August 2000/Accepted 25 January 2001
Degradative strains of fast-growing Mycobacterium
spp. are commonly isolated from polycyclic aromatic hydrocarbon
(PAH)-contaminated soils. Little is known, however, about the ecology
and diversity of indigenous populations of these fast-growing
mycobacteria in contaminated environments. In the present study 16S
rRNA genes were PCR amplified using
Mycobacterium-specific primers and separated by
temperature gradient gel electrophoresis (TGGE), and prominent bands
were sequenced to compare the indigenous Mycobacterium
community structures in four pairs of soil samples taken from heavily
contaminated and less contaminated areas at four different sites.
Overall, TGGE profiles obtained from heavily contaminated soils were
less diverse than those from less contaminated soils. This decrease in
diversity may be due to toxicity, since significantly fewer Mycobacterium phylotypes were detected in soils
determined to be toxic by the Microtox assay than in nontoxic soils.
Sequencing and phylogenetic analysis of prominent TGGE bands indicated
that novel strains dominated the soil Mycobacterium
community. Mineralization studies using [14C]pyrene added
to four petroleum-contaminated soils, with and without the addition of
the known pyrene degrader Mycobacterium sp. strain
RJGII-135, indicated that inoculation increased the level of
degradation in three of the four soils. Mineralization results obtained
from a sterilized soil inoculated with strain RJGII-135 suggested that
competition with indigenous microorganisms may be a significant factor
affecting biodegradation of PAHs. Pyrene-amended soils, with and
without inoculation with strain RJGII-135, experienced both increases
and decreases in the population sizes of the inoculated strain and
indigenous Mycobacterium populations during incubation.
0099-2240/01/$04.00+0 DOI: 10.1128/AEM.67.5.2222-2229.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Mycobacterium Diversity and Pyrene
Mineralization in Petroleum-Contaminated Soils
*
Corresponding author. Mailing address: Department of
Biological Sciences, University of Cincinnati, P.O. Box 210006, Cincinnati, OH 45221-0006. Phone: (513) 556-9756. Fax: (513) 556-5299. E-mail: kinkleb{at}emailuc.edu.
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