Published online by Cambridge University Press: 20 January 2017
Coevolving interactions between a plant population and its microbiota canpotentially yield a rhizosphere enriched in metagenomes containing theblueprints for a vast array of natural products. We describe a method ofisolating those metabolites through activity-based screening of soilmetagenomic libraries. The method allows for the isolation of smallmolecules produced in vector–host expression systems containing large-insertDNA fragments extracted from the target plant rhizospheres. Allelopathicactivities derived from selected clones were screened against a series ofcontrols. Nonmetric multidimensional scaling (NMS) showed similar effects ofthe set of controls on lettuce growth, whereas annual bluegrass had abroader range of growth responses. Methanol extracts from clones indicatingactivity showed distinct patterns in grass seedling growth from the emptyvector control, but the same extracts showed no effect on lettuce. Theresults indicate that the metagenomics method and bioassay screen of cloneextracts are tools that can be used for initial determination ofallelopathic activity from noncultured soil microbiota.
Associate editor for this paper: Franck E. Dayan, USDA-ARS.