Herein we report the isolation of a novel actinomycete, strain MCCB 268^T, from the sediment sample collected from a high Arctic fjord Kongsfjorden. MCCB 268^T showed greater than 97% 16S rRNA gene sequence similarity with those of Pseudonocardia konjuensis LM 157^T (98.06%), Pseudonocardia soli NW8-21 (97.22%) Pseudonocardia endophytica YIM 56035 (97.08%) and Pseudonocardia nantongensis KLBMP 1282 (97.34%) showing that the strain should be assigned to the genus Pseudonocardia. DNA–DNA hybridization with Pseudonocardia konjuensis LM 157^T showed only 41.5% relatedness to strain MCCB 268^T. The whole genome of the strain MCCB 268^T was sequenced. Whole-genome average nucleotide identity, dDDH (%) and genome tree analysis demonstrated that strain significantly differed from other Pseudonocardia species. The G + C content was 70.5 mol%. MCCB 268^T exhibited in vitro cytotoxicity and through bioassay guided fractionation followed by HPLC separation a cytotoxic compound (I) was isolated. The compound (I) was identified as 1-acetyl-β-carboline through NMR spectra and high-resolution mass spectrometry. Compound (I) showed cytotoxicity against lung cancer cell line and mode of anticancer activity was found to be through the induction of apoptosis. Based on the genotypic and phenotypic features, MCCB 268^T ought to be classified as a novel species under the genus Pseudonocardia for which the name Pseudonocardia cytotoxica sp. nov. is proposed (= CCUG72333^T = JCM32718^T).

在本文中，我们报告了一种新型放线菌菌株 MCCB 268 ^T的分离，该菌株是从从高北极峡湾 Kongsfjorden 收集的沉积物样本中分离出来的。MCCB 268 ^Ť显示出与那些的大于97％的16S rRNA基因序列相似性假诺卡konjuensis LM 157 ^Ť（98.06％），假诺卡氏菌索利NW8-21（97.22％）假诺卡endophytica YIM 56035（97.08％）和假诺卡氏菌nantongensis KLBMP 1282（97.34 %) 表明该菌株应归入 Pseudonocardia属。DNA-DNA 与Pseudonocardia konjuensis LM 157 ^T杂交与菌株 MCCB 268 ^T仅显示 41.5% 的相关性。对菌株 MCCB 268 ^T的全基因组进行了测序。全基因组平均核苷酸同一性、dDDH (%) 和基因组树分析表明该菌株与其他Pseudonocardia物种显着不同。G + C 含量为 70.5 mol%。MCCB 268^吨表现出体外细胞毒性，并通过生物测定引导的分级分离，然后进行 HPLC 分离，分离出细胞毒性化合物 (I)。化合物(I)经核磁共振谱和高分辨质谱鉴定为1-乙酰-β-咔啉。化合物(I)显示出对肺癌细胞系的细胞毒性，并且发现抗癌活性模式是通过诱导细胞凋亡。基于基因型和表型特征，MCCB 268 ^T应该被归类为Pseudonocardia属下的一个新物种，其名称Pseudonocardia cytotoxica sp。十一月 建议（= CCUG72333 ^T  = JCM32718 ^T）。