Detection of monochlorobenzene metabolizing bacteria under anoxic conditions by DNA-stable isotope probing
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Cultivation-independent analyses were applied to study the structural diversity of the bacterial community which developed in groundwater inoculated microcosms actively metabolizing monochlorobenzene (MCB) under anaerobic conditions. Addition of 13C-labelled MCB demonstrated that the community produced 13CO2 as a metabolite at slightly increasing rates over a period of 1,051 days while no 13C-methane evolved. Genetic profiles of partial 16S rRNA genes generated with the single-strand conformation polymorphism (SSCP) technique by PCR from directly extracted total DNA revealed that, despite the long incubation period, six replicate microcosms were characterized by almost the same microbial members. Nine distinguishable contributors to the SSCP-profiles were characterized by DNA sequencing, revealing the presence of different members from the phyla Proteobacteria, Fibrobacteres and from the candidate division OD1. DNA-stable isotope probing (SIP) was applied to distinguish the actual MCB metabolizing bacteria from the other community members. This study reveals for the first time the structural diversity of an anaerobic MCB metabolizing bacterial community. However, it also demonstrates the limitations of SIP to detect bacteria slowly metabolizing carbon sources under anaerobic conditions.
KeywordsBiodegradation Contamination Chlorobenzenes Bitterfeld Stable isotope probing
We thank Heidrun Paschke (UFZ Dept. Groundwater Remediation) for providing geochemical data. P. M. M-L. was funded by a European Union Marie Curie Early Stage Training Fellowship (contract number MEST-CT-2004-8332). This work was partially supported by a collaborative project (BACSIN, Contract No. 211684) from the European Commission within its Seventh Framework Program. The project was financially supported by the Helmholtz Centre for Environmental Research.
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