枯草芽胞杆菌262XY2′在玉米根部的定殖动态及对土壤微生物群落的影响

Colonization dynamics of Bacillus subtilis 262XY2′ in maize roots and its effect on soil microbial communities

中文关键词:枯草芽胞杆菌  定殖动态  土壤微生物  群落结构  功能基因

keywords:Bacillus subtilis  colonization dynamic  soil microorganism  community structure  functional gene

中文摘要:为明确枯草芽胞杆菌Bacillus subtilis 262XY2′菌株的定殖能力及对土壤微生物的影响，使用荧光标记菌株通过抗生素平板检测其在土壤和玉米Zea mays不同组织中的定殖动态，利用宏基因组高通量测序分析其对玉米根际土壤微生物群落结构和功能的影响。结果显示：262XY2′菌株在土壤中的定殖数量介于3.32×10⁷~6.24×10⁷ CFU/g之间；在玉米根际、根内、茎秆和叶片中的定殖量分别介于0.86×10⁶~2.46×10⁷、0.59×10⁵~6.80×10⁵、3.67×10²~1.21×10³和4.67×10²~2.17×10³ CFU/g之间。宏基因组测序分析发现，与对照组相比，施用262XY2′颗粒剂后增加了玉米根际土壤中酸杆菌门细菌和子囊菌门及担子菌门真菌的丰度，降低了毛霉菌门真菌的丰度；在属水平，玉米根际土壤中纤维弧菌属Cellvibrio细菌和小菇属Mycena、单孢囊菌属Monosporascus、镰孢菌属Fusarium以及巨孢囊霉属Gigaspora真菌的相对丰度分别增加了91.17%、699.02%、136.37%、52.58%和45.53%，其中玉米根际土壤中镰孢菌属种类减少，枯草芽胞杆菌丰度和次级代谢产物合成相关功能基因丰度显著增加。表明枯草芽胞杆菌262XY2′菌株可在玉米植株体内及土壤中有效定殖，对土壤细菌和真菌的多样性影响不明显，但改变了真菌群落结构，增加有益微生物数量增加，降低病原菌种类，进而改善了土壤微生物群落功能。

Abstract:To clarify the colonization ability of Bacillus subtilis strain 262XY2′ and its effect on soil microorganisms, the strain 262XY2′ with the green fluorescent protein (GFP) gene was used to monitor the colonization dynamics of it on soil and different tissues of maize, which was determined by the viable count of re-isolated 262XY2′ on antibiotic plate. Furthermore, the effects of 262XY2′ on the microbial organisms’structures and functions of the maize rhizosphere soil were determined using highthroughput metagenomic sequencing. The results showed that the viable count of strain 262XY2′ that colonized in the maize soil was 3.32×10⁷-6.24×10⁷ CFU/g, and the viable counts of it in the maize rhizosphere soil, root, stalk, and leaf were 0.86×10⁶-2.46×10⁷, 0.59×10⁵-6.80×10⁵, 3.67×10²-1.21×10³ and 4.67×10²-2.17×10³ CFU/g, respectively. Metagenomic sequencing analysis demonstrated that the abundances of Acidobacteria, Ascomycota and Basidiomycota were all increased in the soil treated with 262XY2′ granules, and the abundance of Mucoromycota was decreased compared with the control. In addition, at the genus level, the relative abundances of Cellvibrio, Mycena, Monosporascus, Fusarium, and Gigaspora compared with control were increased by 91.17%, 699.02%, 136.37%, 52.58% and 45.53%, respectively. Among them, the species of Fusarium were decreased, while the abundance of B. subtilis and the functional genes encoded secondary metabolites were all increased in the rhizosphere soil of maize, which were treated with 262XY2′ granules. In conclusion, B. subtilis 262XY2′ strain could effectively colonize in maize and soil, which could not significantly infect the diversity of bacteria and fungi in soil. However, the colonization of 262XY2′ strain in maize plant and soil can increase the abundance of beneficial microorganisms, reduce the species of pathogenic fungi, and further improve the function of microorganism community.