Metagenomic Assessment of a Complex Microbial Community with Potential Human Pathogens

Metagenomics was applied to study the community genome of uncultured bacteria, those that have not yet been isolated in pure culture and which account for up to 99.9% of some natural microbial consortia.  Uncultured bacterium TM7, originally discovered in environmental habitats has been associated with the human oral disease periodontitis. An analog of the human-associated TM7 has been detected thriving in activated wastewater. Our hypothesis states that metagenomic analysis of the community where this TM7 analog exists, can elucidate the metabolic potential of that community and the requirements for TM7 to grow. Our methods consisted of constructing a fosmid metagenomic library from the TM7 analog habitat to assess the functional diversity of that entire microbial community. Our preliminary results confirmed the presence of TM7 genome. DNA sequences were first compared to the Cluster of Orthologous Groups (COG) database, then tabulated for biochemical functions using the MG-RAST server. Results indicated that the majority of the sequences grouped with the Metabolic proteins category, including Amino Acid, Carbohydrate, Nucleotide and Coenzyme transport and metabolism; in the same manner, the lowest number grouped under Information Storage and Processing category, which contains replication, recombination, repair and transcription enzymes. This information presents the opportunity to study novel genes and understand the functional capability and phylogenetic diversity of the environment where uncultured bacteria grow, which will help us understand their needs.