An overview of the metabolites produced by Photorhabdus and Xenorhabdus (symbiotic bacteria of entmopathogenic nematodes) and their potential use in agriculture as biotic insecticides.

摘要

The genera Photorhabdus and Xenorhabdus are symbiotic bacteria associated with entomopathogenic nematodes of the genera Heterorhabditis and Steinernema, respectively. Photorhabdus and Xenorhabdus secrete in vivo lipases, proteases, phospholipases and other metabolites having antimycotic and antibacterial activities. In vitro, these bacteria also produce metabolites having biological activities against bacteria and fungi. Some of these metabolites with antibacterial properties are new compounds. They are structurally unrelated to clinical antibiotics and are potentially useful for the development of a new class of drugs for fighting human pathogens resistant to today's antibiotics. Aliphatic amides and dithiolopyrrolones produced by Xenorhabdus nematophilus and X. bovienii have been tested as anticancer agents. Substances with nematicidal activity have been detected in fermentation broths of Photorhabdus and Xenorhabdus. Strains of Photorhabdus and Xenorhabdus able to synthesize proteins with insecticidal properties have been selected. These insecticidal toxins could be used as an active biopesticide ingredient in a similar manner to the delta-endotoxins of Bacillus thuringiensis (Bt). This new source of natural toxins could help overcome the development of insect resistance to Bt, to chemical products or to Bt-transgenic plants. Recently, a Photorhabdus toxin was successfully expressed in Arabidopsis thaliana. Several patents obtained for Photorhabdus and Xenorhabdus metabolites include toxins with insecticidal properties. The importance of finding unique strains of these bacteria for the production and purification of bacterial metabolites is discussed..