天山大峡谷原始森林黏细菌的分离鉴定及其抗菌活性

【背景】黏细菌是一类具有多细胞群体行为特征的高等原核生物，其对植物病原真菌和细菌的捕食特性使其在植物病害防治方面具有重要的应用潜力。【目的】探究乌鲁木齐天山大峡谷原始森林可培养黏细菌的多样性并分析其抗菌活性，为发掘黏细菌生防菌株奠定基础。【方法】以天山大峡谷原始森林采集的土样和腐木为分离材料，采用兔粪诱导法和被捕食菌诱导法从中分离纯化黏细菌菌株，结合形态学观察、生理生化测定和16S rRNA基因序列分析确定其分类地位，并以6种植物病原真菌大丽轮枝菌(Verticillium dahliae)、尖孢镰刀菌萎蔫专化型(Fusarium oxysporum f. sp. vasinfectum)、拟轮枝链孢霉(Fusarium verticillioides)、立枯丝核菌(Rhizoctonia solani)、黄色镰刀菌(Fusarium culmorum)、细极链格孢菌(Alternaria tenuissima)]和1种植物病原细菌梨火疫病菌(Erwinia amylovora)]为靶标菌，通过平板对峙法和菌苔捕食法测定其抗菌活性。【结果】从采集的样品中分离出70株菌株，经纯化后获得36株黏细菌纯培养物。经鉴定隶属于4个属，黏球菌属(Myxococcus) 30株、孢囊杆菌属(Cystobacter) 3株、珊瑚球菌属(Corallococcus) 2株和原囊菌属(Archangium) 1株。抗菌活性分析显示，本研究获得的36株黏细菌至少对2种植物病原真菌有抗菌活性，表现出广谱的抗真菌活性，初步筛选出一株菌株NSE37-1兼具广谱和高效抗真菌活性；供试的15株黏细菌对梨火疫病菌均具有捕食活性，初步筛选出一株对梨火疫病菌具有较强捕食能力的黏细菌菌株NSE25。【结论】天山大峡谷可培养黏细菌资源比较丰富，黏球菌属是该地区可培养黏细菌菌群中的优势菌。分离纯化出的黏细菌菌株均表现出广谱的抗植物病原菌活性，具有进一步研究和开发的潜在价值。

Isolation, identification, and antimicrobial activities of myxobacteria in primitive forest of Tianshan Grand Canyon

Background] Myxobacteria are a group of higher prokaryotes with social behavior. They are versatile predators that prey on phytopathogenic fungi and bacteria, serving as excellent candidates for biocontrol agents. Objective] To explore the diversity and antimicrobial activities of culturable myxobacteria in the primitive forest of Tianshan Grand Canyon in Urumqi, and lay a foundation for the discovery of myxobacteria strains for biocontrol. Methods] Culturable myxobacteria were isolated from the soil and rotting wood samples collected from the primitive forest of Tianshan Grand Canyon by the rabbit dung pellets-inducing method and prey-inducing method. The isolates were identified based morphological characteristics, physiological and biochemical properties, and the 16S rRNA gene sequences. The antimicrobial activities of the isolates were determined with 6 phytopathogenic fungal species (Verticillium dahliae, Fusarium oxysporum f. sp. vasinfectum, Fusarium verticillioides, Rhizoctonia solani, Fusarium culmorum, and Alternaria tenuissima) and 1 phytopathogenic bacterial species (Erwinia amylovora) by plate confrontation method and lawn predation method. Results] Seventy potential strains were isolated from the collected samples, and 36 pure cultures of myxobacteria were obtained after purification. The 36 strains belonged to 4 genera: Myxococcus (30 strains), Cystobacter (3 strains), Corallococcus (2 strains), and Archangium (1 strain). The 36 strains of myxobacteria presented activities against at least two species of phytopathogenic fungi, exhibiting broad-spectrum antifungal activities. One strain NSE37-1 with both broad-spectrum efficient antifungal activity was screened out. Fifteen strains had predatory activity against E. amylovora, and one strain NSE25 with strong predatory activity was screened out. Conclusion] The culturable myxobacteria are abundant in Tianshan Grand Canyon, among which Myxococcus is the dominant genus. The isolated and purified myxobacteria strains all exhibited broad-spectrum activities against phytopathogens, demonstrating the value for research in the future.