Liu Shaowei, Wang Ting, Lu Qinpei, Li Feina, Wu Gang, Jiang Zhongke, Habden Xugela, Liu Lin, Zhang Xiaolin, Lukianov Dmitry A, Osterman Ilya A, Sergiev Petr V, Dontsova Olga A, Sun Chenghang
Department of Microbial Chemistry, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Front Microbiol. 2021 Mar 15;12:604999. doi: 10.3389/fmicb.2021.604999. eCollection 2021.
Taklamakan desert is known as the largest dunefield in China and as the second largest shifting sand desert in the world. Although with long history and glorious culture, the Taklamakan desert remains largely unexplored and numerous microorganisms have not been harvested in culture or taxonomically identified yet. The main objective of this study is to explore the diversity, novelty, and pharmacological potential of the cultivable actinomycetes from soil samples at various sites along the Alar-Hotan desert highway in the Taklamakan desert. A total of 590 actinobacterial strains were recovered by the culture-dependent approach. Phylogenetic analysis based on 16S ribosomal RNA (rRNA) gene sequences unveiled a significant level of actinobacterial diversity with 55 genera distributed in 27 families of 12 orders. Thirty-six strains showed relatively low 16S rRNA similarities (<98.65%) with validly described species, among which four strains had already been characterized as novel taxa by our previous research. One hundred and forty-six actinobacterial isolates were selected as representatives to evaluate the antibacterial activities and mechanism of action by the paper-disk diffusion method and a double fluorescent protein reporter "pDualrep2" system, respectively. A total of 61 isolates exhibited antagonistic activity against the tested "ESKAPE" pathogens, among which seven strains could produce bioactive metabolites either to be able to block translation machinery or to induce SOS-response in the pDualrep2 system. Notably, sp. 16Sb2-4, harboring a promising antibacterial potential with the mechanism of interfering with protein translation, was analyzed in detail to gain deeper insights into its bioactive metabolites. Through ultra-performance liquid chromatography (UPLC)-quadrupole time-of-flight (QToF)-MS/MS based molecular networking analysis and databases identification, four families of compounds (-) were putatively identified. Subsequent bioassay-guided separation resulted in purification of four 16-membered macrolide antibiotics, aldgamycin H (), aldgamycin K (), aldgamycin G (), and swalpamycin B (), and their structures were elucidated by HR-electrospray ionization source (ESI)-MS and NMR spectroscopy. All compounds - displayed antibacterial activities by inhibiting protein synthesis in the pDualrep2 system. In conclusion, this work demonstrates that Taklamakan desert is a potentially unique reservoir of versatile actinobacteria, which can be a promising source for discovery of novel species and diverse bioactive compounds.
塔克拉玛干沙漠是中国最大的沙漠，也是世界第二大流动沙漠。尽管有着悠久的历史和灿烂的文化，但塔克拉玛干沙漠在很大程度上仍未被探索，许多微生物尚未通过培养收获或进行分类鉴定。本研究的主要目的是探索塔克拉玛干沙漠阿拉尔-和田沙漠公路沿线不同地点土壤样品中可培养放线菌的多样性、新颖性和药理潜力。通过依赖培养的方法共回收了590株放线菌菌株。基于16S核糖体RNA（rRNA）基因序列的系统发育分析揭示了放线菌的显著多样性，55个属分布在12个目27个科中。36株菌株与有效描述的物种显示出相对较低的16S rRNA相似性（<98.65%），其中4株已被我们先前的研究鉴定为新分类单元。分别选择146株放线菌分离株作为代表，通过纸片扩散法和双荧光蛋白报告基因“pDualrep2”系统评估其抗菌活性和作用机制。共有61株分离株对测试的“ESKAPE”病原体表现出拮抗活性，其中7株能够产生生物活性代谢物，要么能够阻断翻译机制，要么能够在pDualrep2系统中诱导SOS反应。值得注意的是，对具有干扰蛋白质翻译机制且具有潜在抗菌潜力的菌株sp. 16Sb2-4进行了详细分析，以深入了解其生物活性代谢物。通过基于超高效液相色谱（UPLC）-四极杆飞行时间（QToF）-MS/MS的分子网络分析和数据库鉴定，推测鉴定出四类化合物（-）。随后的生物活性导向分离纯化得到了四种16元大环内酯抗生素，aldgamycin H（）、aldgamycin K（）、aldgamycin G（）和swalpamycin B（），并通过高分辨电喷雾电离源（ESI）-MS和核磁共振光谱确定了它们的结构。所有化合物 - 通过在pDualrep2系统中抑制蛋白质合成表现出抗菌活性。总之，这项工作表明塔克拉玛干沙漠是一个潜在的独特的多功能放线菌库，有望成为发现新物种和多样生物活性化合物的来源。
