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Bacillus thuringiensis is a gram-positive and spore-forming bacterium that synthesizes a wide diversity of proteins with insecticidal activity and which has demonstrated its potential and safety as a biocontrol agent for more than four decades. However, several susceptible insect species have been reported for evolving resistance, which demands screening for strains exhibiting novel insecticidal properties. In this work, we performed the genome sequence analysis and the insecticidal characterization of B. thuringiensis strain Bt-UNVM_94 isolated from Argentina. This strain produced quasi symmetric bipyramidal parasporal crystals as shown using Scanning Electron Microscopy. Its genomic sequence harbours one coding sequence showing homology to the crystal toxin Cry7Ga2 and another, with similarity to the Mpp2Aa3 (Mtx2) toxin. Known Cry7A and Cry7B are known to be active against some coleopteran and lepidopteran larvae, respectively. However, bioassays performed with spore-crystal mixtures of strain Bt-UNVM_94 exhibited dual toxicity with 50% and 91% mortality against Cydia pomonella (Lepidoptera: Tortricidae) and Anthonomus grandis (Coleoptera: Curculionidae), respectively. No toxicity was detected against the free-living nematode Panagrellus redivivus (Rhabditidae: Panagrolaimidae). This strain also showed no PCR amplification of the type I b-exotoxin thuE gene, consistent with the absence of mortality in b-exotoxin bioassays with Musca domestica (Diptera: Muscidae). Screenings of novel B. thuringiensis strains may provide toxins with novel insecticidal properties that can be used to suppress insect resistance to the most used B. thuringiensis-crops in the field.

Entomopathogenic nematodes belonging to the genus Steinernema are able to infest and kill insect hosts in association with their resident, entomopathogenic symbiont bacteria in the gram-negative genus Xenorhabdus (Enterobacteriaceae). However, only a few species of Xenorhabdus have been isolated from their hosts and their insecticidal properties reported. Here we performed the genome sequence analysis of 14 Xenorhabdus strains isolated from Steinernema nematodes in Argentina, able to kill 6th instar Galleria mellonella (Lepidoptera) larvae. The 14 draft genome sequences encoded 110 putative insecticidal toxins (Tc, Pir and Mcf toxin homologs) plus other virulence factors with similarity to putative nematicidal toxins and chitinases. The genome sequences of strains Flor, 5, PSL, Reich, 42, Vera, M, 18, Cul, DI, 12, 38, 3 and ZM exhibited 4, 9, 2, 10, 9, 5, 7, 10, 10, 7, 3, 18, 8 and 8 putative insecticidal toxin genes, respectively. Strains 5, Reich, 42, 18, DI, 38, 3 and ZM carried their predicted insecticidal toxin genes arranged into putative pathogenicity islands whereas strains Flor, PSL, Vera, M, Cul and 12) showed them spread thorough different contigs. Multigene phylogenetic analysis and average nucleotide identity (ANI) calculations were also performed and allowed the identification of three strains (PSL, Reich and 12) that should be considered as novel Xenorhabdus genomospecies. In this work, we provide a dual insight into the diversity of the species belonging to the Xenorhabdus genus and into their predicted insecticidal toxin repertory, which is currently under investigation.