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Abstract：
One Gram-negative, rod-shaped bacterial strain, isolated from an undescribed Heterorhabditis entomopathogenic nematode species was characterized to determine its taxonomic position. The 16S rRNA gene sequences indicate that it belongs to the class Gammaproteobacteria, to the family Morganellaceae, to the genus Photorhabdus, and likely represents a novel bacterial species. This strain, designated here as CRI-LCT, was therefore molecularly, biochemically, and morphologically characterized to describe the novel bacterial species. Phylogenetic reconstructions using 16S rRNA gene sequences show that CRI-LCT is closely related to P. laumondii subsp. laumondii TT01T and to P. laumondii subsp. clarkei BOJ-47T. The 16rRNA gene sequences between CRI-LCT and P. laumondii subsp. laumondii TT01T are 99.1% identical, and between CRI-LCT and P. laumondii subsp. clarkei BOJ-47T are 99.2% identical. Phylogenetic reconstructions using whole genome sequences show that CRI-LCT is closely related to P. laumondii subsp. laumondii TT01T and to P. laumondii subsp. clarkei BOJ-47T. Moreover, digital DNA-DNA hybridization (dDDH) values between CRI-LCT and its two relative species P. laumondii subsp. laumondii TT01T and P. laumondii subsp. clarkei BOJ-47T are 65% and 63%, respectively. In addition, we observed that average nucleotide identity (ANI) values between CRI-LCT and its two relative species P. laumondii subsp. laumondii TT01T and P. laumondii subsp. clarkei BOJ-47T are 95.8% and 95.5%, respectively. These values are below the 70% dDDH and the 95-96% ANI divergence thresholds that delimits prokaryotic species. Based on these genomic divergence values, and the phylogenomic separation, we conclude that CRI-LCT represents a novel bacterial species, for which we propose the name Photorhabdus africana sp. nov. with CRI-LCT (= CCM 9390T = CCOS 2112T) as the type strain. The following biochemical tests allow to differentiate P. africana sp. nov. CRI-LCT from other species of the genus, including its more closely related taxa: β-Galactosidase, citrate utilization, urease and tryptophan deaminase activities, indole and acetoin production, and glucose and inositol oxidation. Our study contributes to a better understanding of the taxonomy and biodiversity of this important bacterial group with great biotechnological and agricultural potential.
摘要：
一个革兰氏阴性，杆状细菌菌株，从未描述的异型横纹肌中分离出昆虫病原线虫物种，以确定其分类学位置。16SrRNA基因序列表明它属于γ变形菌，莫甘草科，光峰结构属，很可能代表了一种新的细菌。这个菌株,这里指定为CRI-LCT，因此在分子上，生物化学，并进行形态学表征以描述新的细菌物种。使用16SrRNA基因序列进行的系统发育重建表明，CRI-LCT与劳蒙迪亚种密切相关。劳蒙迪TT01T和劳蒙迪亚种。clarkeiBOJ-47T.CRI-LCT和劳蒙地氏疟原虫亚种之间的16rRNA基因序列。laumondiiTT01T是99.1%相同，以及CRI-LCT和P.laumondii亚种之间的关系。clarkeiBOJ-47T是99.2%相同。使用全基因组序列进行的系统发育重建表明，CRI-LCT与劳蒙迪亚种密切相关。劳蒙迪TT01T和劳蒙迪亚种。clarkeiBOJ-47T.此外，CRI-LCT与其两个相对物种劳蒙迪亚种之间的数字DNA-DNA杂交（dDDH）值。劳蒙迪TT01T和劳蒙迪亚种。克拉基BOJ-47T分别为65%和63%，分别。此外,我们观察到CRI-LCT及其两个相对物种P.laumondii亚种之间的平均核苷酸同一性（ANI）值。劳蒙迪TT01T和劳蒙迪亚种。克拉基BOJ-47T分别为95.8%和95.5%，分别。这些值低于界定原核物种的70％dDDH和95-96％ANI发散阈值。基于这些基因组差异值，和系统基因组分离，我们得出结论，CRI-LCT代表了一种新的细菌物种，为此，我们建议将其命名为非洲的Photorhabdussp。11月。以CRI-LCT(=CCM9390T=CCOS2112T)为类型菌株。以下生化测试可以区分非洲假单胞菌。11月。来自该属其他物种的CRI-LCT，包括其更密切相关的类群：β-半乳糖苷酶，柠檬酸盐利用，脲酶和色氨酸脱氨酶活性，吲哚和丙酮的生产，葡萄糖和肌醇氧化。我们的研究有助于更好地了解这一具有巨大生物技术和农业潜力的重要细菌群的分类学和生物多样性。
