库木塔格沙漠土壤细菌多样性及具有群体感应抑制活性放线菌筛选

Bacterial diversity in the soil from Kumutag Desert and screening of actinomycetes with quorum sensing inhibitory activity

摘要:

【背景】群体感应抑制剂(quorum sensing inhibitor, QSI)作为抗生素潜在替代品，可有效降低致病菌传染性和毒性。沙漠土壤蕴藏着丰富的放线菌资源，是挖掘群体感应抑制剂的重要来源。【目的】解析库木塔格沙漠土壤细菌群落多样性，筛选并挖掘群体感应抑制活性放线菌资源。【方法】采用Illumina NovaSeq高通量测序技术揭示库木塔格沙漠土壤细菌群落组成，利用可培养方法进行土壤放线菌分离和鉴定；选用紫色杆菌CV026模型筛选群体感应抑制活性放线菌，并对其功能特性进行初步评价。【结果】Illumina NovaSeq高通量测序结果显示，样品土壤细菌涉及23门96目150属，优势菌门为变形菌门(Proteobacteria, 61%)、放线菌门(Actinobacteria, 28%)，其中分枝杆菌属(Mycobacterium)为放线菌门最优势菌属(87.3%)，其次为红球菌属(Rhodococcus, 6.8%)和丙酸杆菌属(Cutibacterium, 0.9%)。可培养方法共分离到108株放线菌，归属9科10属，其中优势菌属为链霉菌属(Streptomyces)，占65.76%。经筛选共得到13株具有群体感应抑制活性的放线菌，包括链霉菌属(Streptomyces) 10株，拟诺卡氏菌属(Nocardiopsis)、Bailinhaonella和拟孢囊菌属(Kibdelosporangium)各1株，其中Streptomyces sp. D67表现出较为广谱的抑菌特性。【结论】库木塔格沙漠土壤细菌多样性较为丰富，并获得多株具有群体感应抑制活性放线菌，且部分菌株具有较强的抑菌活性，为后续天然群体感应抑制剂和抗菌剂的开发提供菌种资源，并为新型生物医药的合成、生物防治等方面提供理论依据。

Abstract:

[Background] Quorum sensing inhibitor (QSI), promising alternatives to antibiotics, can reduce the infectivity and virulence of pathogenic bacteria by interrupting quorum sensing pathways. Desert soils contain rich actinomycetes, which are an important source for the mining of QSI. [Objective] To investigate the bacterial diversity in the soil from Kumutag Desert and screen out the actinomycetes with the quorum sensing inhibitory activity. [Methods] Illumina NovaSeq high-throughput sequencing was employed to reveal the composition of bacterial community in the soil of Kumtag Desert, and the culture method to isolate the actinomycetes. The Chromobacterium violaceum 026 model was used for the screening of the actinomycetes with quorum sensing inhibitory activity. The functions of the strains screened out were initially evaluated. [Results] The soil samples harbored 150 genera of bacteria belonging to 96 orders of 23 phyla. The dominant phyla were Proteobacteria (61%) and Actinobacteria (28%). As for Actinobacteria, the genus with the highest relative abundance was Mycobacterium (87.3%), followed by Rhodococcus (6.8%) and Cutibacterium (0.9%). A total of 108 isolates were obtained and identified as actinomycetes belonging to 10 genera of nine families, in which the dominant genus was Streptomyces (65.76%). Thirteen strains with quorum sensing inhibitory activity were screened out, including 10 strains of Streptomyces and each one strain of Nocardiopsis, Bailinhaonella, and Kibdelosporangium. Strain Streptomyces sp. D67 exhibited broad-spectrum antimicrobial activities. [Conclusion] The bacteria in the soil of Kumutag Desert have high diversity and contain multiple strains of actinomycetes with quorum sensing inhibitory activity. Several strains with quorum sensing inhibitory activity demonstrate strong antimicrobial activity, which provide strain resources for the subsequent development of natural QSI and antimicrobial agents and lay a theoretical foundation for the development of biopharmaceuticals and biocontrol.