Notice Board

How do we develop a more thorough understanding of the vast majority of microbes on Earth
that have never been successfully cultured? Many of these microbes are known from their
DNA sequences, but not well understood. Metagenomics is a DNA sequence-based technology
that facilitates the study of uncultured organisms in microbial communities at the genetic
level. It relies on extraction of DNA directly from environmental samples. Whereas sequencebased
metagenomics involves comparison to databases of known genes, function-based
metagenomics aims to identify novel sequence / function relationships. Phenotypic screening
of cloned and expressed environmental DNA has the potential to contribute to the discovery
of novel sequences for biochemical activities, while enhancing the overall knowledge of the
relationship between sequence and function. It has already been demonstrated that this
approach leads to discovery of genes that would not have been associated with given
functions by sequence analysis alone. This knowledge should improve the quality of sequence
database annotations that are fundamental to sequence-based metagenomics, microbial
systems biology, synthetic biology, and genome engineering.

A challenge in functional metagenomics is that the host background often limits the diversity
of genes isolated, due to differential requirements for gene expression. To address this
challenge, we have emphasized the development of tools for screening in multiple host
backgrounds. We construct large insert cosmid libraries that are able to replicate in a variety
of different hosts, and design screens that often involve complementation of mutant
phenotypes. We maintain the Canadian MetaMicroBiome Library resource, from which many
of our metagenomic libraries are made available to the scientific community. Using these
libraries, we have isolated novel genes for quorum sensing, phosphonate degradation,
glycoside hydrolysis, and polyhydroxyalkanaote synthesis and degradation. Some examples of
these studies will be highlighted, with the aim of providing an overview of our current
research program and plans for the future.