毛竹根际解磷菌木糖氧化无色杆菌的分离及其解磷机制

Isolation and phosphorus-solubilizing mechanism of Achromobacter xylosoxidans in the rhizosphere of Moso bamboo

摘要:

目的 分离毛竹(Phyllostachys edulis)根际兼备溶解无机磷和有机磷能力的菌株，挖掘菌株解磷相关的功能基因，为利用解磷微生物活化土壤磷库、提高土壤磷有效性奠定基础。方法 以亚热带地区重要经济林木——毛竹为研究对象，采用高通量筛选技术分离毛竹根际解磷菌。通过微孔板培养和土壤接种实验，分别探究碳源类型和土壤磷含量对其解磷能力的影响。采用全基因组测序技术解析其与解磷相关的基因，以探究其解磷机制。结果 筛选出一株多途径解磷的细菌，命名为zafu-3，鉴定为木糖氧化无色杆菌(Achromobacter xylosoxidans)。该菌株能利用葡萄糖和柠檬酸等4种碳源来溶解Ca₃(PO₄)₂、FePO₄、AlPO₄、卵磷脂和植酸钙，最佳解磷效果为32.75 mg/(L·d)。与对照组相比，接种菌株zafu-3后，土壤酸性和碱性磷酸酶活性分别增加了4.21%-33.88%和13.54%-112.06%，特别是在高磷土壤中，土壤pH值降低了0.04，有效磷含量增加了16.32%。全基因组结果表明，该菌株包含了35个参与磷酸水解酶编码的基因和53个参与有机酸代谢的编码基因。此外，菌株zafu-3具有产生产吲哚乙酸、铁载体和降解木质素的相关功能基因。结论 菌株zafu-3可通过分泌多种有机酸和磷酸酶直接溶解无机和有机磷源，并可能通过促进植物生长间接激活土壤磷库，这为多功能生物肥料的开发提供了重要的菌种资源和科学依据。

Abstract:

Objective To isolate the strain for solubilizing both inorganic and organic phosphorus (P) from the rhizosphere of Moso bamboo (Phyllostachys edulis) and mine the related genes, laying a foundation for activating the soil P pool and improving P bioavailability by P-solubilizing microorganisms (PSM).Methods High-throughput screening was employed to isolate PSM strains from the rhizosphere of Moso bamboo, an important economic plant in subtropical regions. The P-solubilizing activities of the strain under various carbon sources and soil P levels were investigated by microplate culture and soil inoculation experiments, respectively. The genes involved in P solubilizing of the strain were mined by whole-genome sequencing.Results The strain zafu-3 (Achromobacter xylosoxidans) capable of solubilizing P via multiple pathways was isolated from the rhizosphere of Moso bamboo. The strain solubilized Ca₃(PO₄)₂, FePO₄, AlPO₄, lecithin, and calcium phytate by using four carbon sources such as glucose and citric acid, with the highest P-solubilizing activity of 32.75 mg/(L·d). Compared with the control group, the zafu-3 inoculation group showed increases of 4.21%-33.88% and 13.54%-112.06% in activities of acid phosphatase and alkaline phosphatase, respectively. In the high P-level soil, inoculation of the strain decreased the soil pH by 0.04 and increased the available P content by 16.32%. The whole genome of strain zafu-3 contained 35 genes encoding phosphohydrolases and 53 genes involved in organic acid metabolisms. Furthermore, strain zafu-3 carried the genes associated with the production of indole-3-acetic acid and siderophores, and the degradation of lignin.Conclusion Strain zafu-3 directly solubilized inorganic and organic P by secreting diverse organic acids and phosphatases, and indirectly activated soil P pools by promoting plant growth. These findings provide an important microbial resource and theoretical foundation for the development of multifunctional biofertilizers.