稻田高效固氮蓝细菌的筛选鉴定及其促生潜力

Screening and identification of efficient nitrogen-fixing cyanobacteria with plant growth-promoting potential from paddy fields

【背景】稻田的长期淹水环境和水稻的根系分泌物为固氮微生物提供了适宜的环境条件,其中固氮蓝细菌是稻田生物固氮的主要贡献者。【目的】获得高效固氮蓝细菌菌株,为稻田生物固氮能力的提高提供菌种资源。【方法】采用BG-110无氮培养基从不同水稻土中分离培养固氮蓝细菌。通过对固氮酶活性、吲哚-3-乙酸(indole-3-acetic acid,IAA)分泌能力和铁载体生成能力的测定对分离菌株进行筛选,对筛选出的高效固氮菌株进行形态学和分子生物学鉴定,并通过水培试验和盆栽试验评价该菌株的促生潜力。【结果】筛选出一株固氮能力高[239.27 nmol/(min·mg)]、IAA产量大(7.70μg/mL)和铁载体生成能力强的菌株。经鉴定,该菌株属于念珠藻科(Nostocaceae)Aliinostoc属,命名为Aliinostoc sp.d389-10。水培试验结果表明,菌株d389-10能够显著促进水稻幼苗的生长,施用该菌后水稻幼苗株高、根长和干重分别增加22.42%、54.76%和57.80%。在盆栽试验中,接种菌株d389-10能够显著提高土壤固氮酶活性和水稻产量,同时显著增加土壤有机碳、全氮和速效养分含量。【结论】菌株d389-10是兼具促生能力的高效固氮蓝细菌菌株,是具有研究价值和应用潜力的微生物菌种资源。

[Background]The long-term flooding conditions in paddy fields and root exudates of rice plants create a favorable environment for nitrogen-fixing microorganisms,among which nitrogen-fixing cyanobacteria are the main contributors to biological nitrogen fixation in paddy ecosystems.[Objective]To obtain efficient nitrogen-fixing cyanobacterial strains and provide strain resources for enhancing biological nitrogen fixation in paddy fields.[Methods]The BG-110 nitrogen-free medium was used to isolate nitrogen-fixing cyanobacteria from different paddy soil samples.The isolates were screened based on nitrogenase activity,indole-3-acetic acid(IAA)secretion ability,and siderophore production ability.The selected efficient nitrogen-fixing strain was identified by morphological observation and methods of molecular biology.The plant growth-promoting effect of the selected strain was evaluated by hydroponic and pot experiments.[Results]An efficient nitrogen-fixing[239.27 nmol/(min·mg)]strain with high IAA production(7.70μg/mL)and robust siderophore secretion ability was screened out.It was identified as a strain belonging to Aliinostoc of Nostocaceae and named Aliinostoc sp.d389-10.This strain significantly promoted the growth of rice seedlings in hydroponic experiments,increasing the plant height,root length,and dry weight by 22.42%,54.76%,and 57.80%,respectively.In pot experiments,inoculation with d389-10 significantly improved soil nitrogenase activity and rice yield,while significantly increasing soil organic carbon,total nitrogen,and available nutrients.[Conclusion]The strain d389-10 screened out is an efficient nitrogen-fixing cyanobacterial strain with rice growth-promoting effect,with research value and application potential.