Symbiotic micro‐organisms of insects: A potential new source for biologically active substances

Symbiotic micro‐organisms isolated from insects have been shown to be a potential new source for antimicrobial substances. Diacetylphloroglucinol and pyoluteorin were produced by a bacterial symbiont of the white‐backed planthopper, Sogatella furcifera. Diacetylphloroglucinol was also produced by a fungal ectosymbiont of an ambrosia beetle, Scolytoplatypus mikado. A peptide antibiotic, polymyxin E1, was isolated from the cultured broth of an intracellular symbiont identified as Bacillus polymyxa, isolated from an oriental stinkbug, Plautia stali. An Enterobacter sp. bacterial symbiont of the brown planthopper, Nilaparvata lugens, produced a novel antibacterial substance, andrimid, whose antibacterial spectrum is unique, displaying potent activity only against the bacterial blight pathogen of the rice plant, Xanthomonas campestris pv. oryzae, and a few other bacteria.