Description and charactrization of the Amazonian entomopathogenic bacteriumPhotorhabdus luminescensMN7

AbstractMany isolates of the genusPhotorhabdushave been reported around the world. Here we describe the first BrazilianPhotorhabdusisolate, found in association with the entomopathogenic nematodeHeterorhabditis baujardiLPP7, from the Amazonian forest in Monte Negro (RO, Brazil). The new isolate can be grouped with the Hb-Hm clade ofP. luminescenssubsp.luminescens, close to the new subspeciesP. luminescenssubsp.sonorensis. P. luminescensMN7 has several characteristics expected of variant form I cells, such as the presence of intracellular crystals, secretion of hydrolytic enzymes (lipases and proteases) and bioluminescence. AlthoughH. baujardiLPP7 is not prolific when compared toH. bacteriophoraHP88,P. luminescensMN7 is clearly pathogenic and probably secretes the same toxins asP. luminescenssubsp.luminescensW14, when fed to larvae of the greater wax mothGalleria mellonella. This behavior is different from what is found inPhotorhabdus luminescenssubsp.laumondiiHP88, which was used as a control in our experiments, andP. l. subsp.laumondiiTT01. Besides the toxin secretion,P. luminescensMN7 secretes proteolytic polypeptides that have molecular masses different from those found inP. l. subsp.laumondiiTT01. Finally, the crude extract from spent culture medium was shown to contain 3,5-dihydroxy-4-isopropyl-cis-stilbene and 1,3,8-trihydroxy-9,10-anthraquinone as the major compounds, similarly to otherPhotorhabdus luminescensstrains.