Anaerobic Methyl tert-Butyl Ether-Degrading Microorganisms Identified in Wastewater Treatment Plant Samples by Stable Isotope Probing

Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan, USA.
Applied and Environmental Microbiology (Impact Factor: 3.67). 02/2012; 78(8):2973-80. DOI: 10.1128/AEM.07253-11
Source: PubMed


Anaerobic methyl tert-butyl ether (MTBE) degradation potential was investigated in samples from a range of sources. From these 22 experimental
variations, only one source (from wastewater treatment plant samples) exhibited MTBE degradation. These microcosms were methanogenic
and were subjected to DNA-based stable isotope probing (SIP) targeted to both bacteria and archaea to identify the putative
MTBE degraders. For this purpose, DNA was extracted at two time points, subjected to ultracentrifugation, fractioning, and
terminal restriction fragment length polymorphism (TRFLP). In addition, bacterial and archaeal 16S rRNA gene clone libraries
were constructed. The SIP experiments indicated bacteria in the phyla Firmicutes (family Ruminococcaceae) and Alphaproteobacteria (genus Sphingopyxis) were the dominant MTBE degraders. Previous studies have suggested a role for Firmicutes in anaerobic MTBE degradation; however, the putative MTBE-degrading microorganism in the current study is a novel MTBE-degrading
phylotype within this phylum. Two archaeal phylotypes (genera Methanosarcina and Methanocorpusculum) were also enriched in the heavy fractions, and these organisms may be responsible for minor amounts of MTBE degradation
or for the uptake of metabolites released from the primary MTBE degraders. Currently, limited information exists on the microorganisms
able to degrade MTBE under anaerobic conditions. This work represents the first application of DNA-based SIP to identify anaerobic
MTBE-degrading microorganisms in laboratory microcosms and therefore provides a valuable set of data to definitively link
identity with anaerobic MTBE degradation.

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