Xenorhabdus nematophila: Mutualist and Pathogen

T he gram-negative bacterium Xenorhabdus nematophila engages in a mutualistic relationship with a specific soil nematode and also can mount potent pathogenic attacks on a variety of insects. During its mutualisticpathogenic life cycle, Xenorhabdus produces a wide range of exoenzymes, antimicrobial and nematicidal compounds, and insect toxins. Moreover, the nematode-bacteria complex is useful for managing diverse agricultural pests. These properties, plus its genetic tractability, make Xenorhabdus an excellent model system for studying both bacterial-animal mutualism and pathogenicity, and for developing useful products for medicine, agriculture, and biotechnology. The tripartite X. nematophila-Steinernema carpocapsae-insect interaction is also useful for studying the molecular mechanisms governing both symbiotic and pathogenic interactions between bacteria and animal hosts.