Why Sequence a Terephthalate-Degrading Microbial Community?

Every year, enormous amounts of high-strength terephthalate-containing wastewater are produced as a byproduct of the plastics industry. The wastewater is currently treated by using anaerobic biological treatment processes that involve mesophilic (moderate-temperature-loving) microbes growing at 35-37°C. Recently, a thermophilic (heating-loving) terephthalate-degrading community growing at around 55°C has been developed in a lab-scale bioreactor as a more efficient alternative to the mesophilic process. Metagenomic characterization of the thermophilic bioreactor community, followed by perturbation studies, may lead to an optimized process, which will have significant impact on the plastic production industry in terms of wastewater treatment costs and operational stability. Furthermore, it may then be possible to engineer nutritionally interdependent (syntrophic) microbial communities to treat chemical-contaminated environments.

A stable thermophilic terephthalate-degrading community has been well characterized by 16S rRNA-based methods. This bioreactor community is extremely simple, comprising three dominant populations, Pelotomaculum (a member of the Firmicutes phylum that converts terephthalate to acetate and hydrogen), Methanothrix (an archaeon that converts acetate to methane and carbon dioxide), and a representative of candidate bacterial phylum OP5 (unknown function, but may also ferment terephthalate). In addition, thermophilic methanogens that convert hydrogen and part of the carbon dioxide produced to methane were also detected in low abundance.

This project will provide the first genomic sequence data for candidate phylum OP5. In addition, the microbes will provide an excellent model community for metagenomic sequencing with a high probability of sequence assembly and metabolic reconstruction from 100 Mb of sequence data. Since the populations are so phylogenetically disparate, binning the genomic fragments into their respective populations should be relatively straightforward. This community also provides a simple model for the study of the syntrophic association between fermentative bacteria and methanogens.

CSP project participants: Wen-Tso Liu (proposer, Natl. Univ. of Singapore); Philip Hugenholtz and Natalia Ivanova (JGI), Jizhong Zhou (Oak Ridge Natl. Lab. and Univ. of Tennessee), Hervé Macarie (Institut de Recherche pour le Développement, France), and Alejandro Olmos and Oscar Monroy (Universidad Autónoma Metropolitana-Iztapalapa, Mexico).