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Abstract：
Entomopathogenic nematodes from the genus Steinernema (Nematoda: Steinernematidae) are capable of causing the rapid killing of insect hosts, facilitated by their association with symbiotic Gram-negative bacteria in the genus Xenorhabdus (Enterobacterales: Morganellaceae), positioning them as interesting candidate tools for the control of insect pests. In spite of this, only a limited number of species from this bacterial genus have been identified from their nematode hosts and their insecticidal properties documented. This study aimed to perform the genome sequence analysis of fourteen Xenorhabdus strains that were isolated from Steinernema nematodes in Argentina. All of the strains were found to be able of killing 7th instar larvae of Galleria mellonella (L.) (Lepidoptera: Pyralidae). Their sequenced genomes harbour 110 putative insecticidal proteins including Tc, Txp, Mcf, Pra/Prb and App homologs, plus other virulence factors such as putative nematocidal proteins, chitinases and secondary metabolite gene clusters for the synthesis of different bioactive compounds. Maximum-likelihood phylogenetic analysis plus average nucleotide identity calculations strongly suggested that three strains should be considered novel species. The species name for strains PSL and Reich (same species according to % ANI) is proposed as Xenorhabdus littoralis sp. nov., whereas strain 12 is proposed as Xenorhabdus santafensis sp. nov. In this work, we present a dual insight into the biocidal potential and diversity of the Xenorhabdus genus, demonstrated by different numbers of putative insecticidal genes and biosynthetic gene clusters, along with a fresh exploration of the species within this genus.
摘要：
来自Steinernema属的昆虫病原线虫（Nematoda：Steinernematidae）能够迅速杀死昆虫宿主，通过它们与Xenorabdus属（肠杆菌：Morganellaceae）中的共生革兰氏阴性细菌的结合而促进，将它们定位为控制害虫的有趣候选工具。尽管如此,从线虫宿主中只鉴定了该细菌属的有限数量的物种，并记录了它们的杀虫特性。这项研究旨在对从阿根廷的Steinernema线虫中分离出的14株Xenorhabdus菌株进行基因组序列分析。发现所有菌株都能够杀死Galleriamellonella的7龄幼虫（L.）（鳞翅目：Pyralidae）。他们的测序基因组含有110种推定的杀虫蛋白，包括Tc，Txp,Mcf,Pra/Prb和应用程序同源物，加上其他毒力因子，如推定的杀线虫蛋白，几丁质酶和次级代谢产物基因簇，用于合成不同的生物活性化合物。最大似然系统发育分析加上平均核苷酸同一性计算强烈表明，应将三种菌株视为新物种。PSL和Reich菌株的物种名称（根据％ANI相同的物种）被提议为Xenorhabduslittoralissp。11月。,而菌株12被提议为Xenorhabdussantafensissp。11月。在这项工作中,我们对Xenorhabdus属的杀生物潜力和多样性提出了双重见解，由不同数量的推定杀虫基因和生物合成基因簇证明，以及对该属内物种的新探索。
