固氮芽孢杆菌N3的筛选鉴定及其对二月兰的促生效果

Isolation and Characterization of Bacillus Nitrogen-Fixing Bacteria and Its Growth-Promotion on Orychophragmus violaceus

从山东泰安农田土壤中筛选获得1株固氮能力强的菌株N3,通过形态观察、生理生化特征以及16S rDNA基因序列分析,确定为巨大芽孢杆菌属(Bacillus megaterium),该菌株固氮酶活性达C2H428.33 nmol/(h·ml)。温室条件下进行二月兰盆栽试验,设置不接菌对照(CK)、接种巨大芽孢杆菌N3、接种产吲哚乙酸(IAA)菌CDL29和复合接种菌株N3+CDL29四个处理,探讨了接种不同植物促生菌对二月兰的促生效果。结果表明:接种植物促生菌均促进二月兰的生长,且单一接种固氮菌株N3的促生效果最好,其显著提高二月兰地上部氮、磷和地下部氮、钾的含量,相比对照,增幅分别为33.03%、55.56%和29.87%、51.11%,其他处理也有提高二月兰养分含量的趋势,但并不显著;单一接种菌株N3,土壤有机质、全氮和速效养分含量显著提高;接种植物促生菌均提高土壤微生物生物量碳(MBC)和氮(MBN)的含量,单一接种固氮菌株N3提升效果最佳,接种产IAA菌株CDL29和复合接种次之。此外,接种固氮菌株N3能够显著提升土壤固氮酶活性,接种菌株CDL29对土壤固氮酶活性没有显著影响。因此,单一接种固氮菌株N3在促进二月兰生长、养分含量提高及土壤理化和生物学性质改良上都具有显著的效果。

A strain N3 with strong nitrogen fixation ability was selected from the farmland soil in Taian,Shandong Province and was identified as Bacillus megaterium based on the morphological,physiological and biochemical characteristics and 16S rDNA gene sequences analysis.Its nitrogenase activity was up to C2H428.33 nmol/(h·ml).Four treatments were set to explore the inoculation effect of different plant growth-promoting bacterium on the growth of Orychophragmus violaceus,including single or double inoculation of strain N3 or IAA(indole-3-acetic acid)-producing stain Pantoea agglomerans CDL29,plant without any inoculation set as the control treatment(CK).The pot experiment of Orychophragmus violaceus was conducted under greenhouse conditions.The results showed that all plant growth-promoting bacteria promoted the growth of Orychophragmus violaceus,and the treatment with single inoculation of nitrogen-fixing strain N3 was the best.At the same time,nitrogen and phosphorus contents in the shoots of Orychophragmus violaceus,nitrogen and potassium contents in the roots of Orychophragmus violaceus were significantly increased by the single inoculation of nitrogen-fixing strain N3,which were increased by 33.03%,55.56%and 29.87%,51.11%respectively compared with CK.Other treatments also promoted nutrient contents in Orychophragmus violaceus,but the trends were not statistic significant.The contents of soil organic matter,total nitrogen and available nutrients were significantly increased by single inoculation of nitrogen-fixing strain N3.The contents of soil microbial carbon(MBC)and microbial nitrogen(MBN)were increased by the inoculation of different plant probiotics,single inoculation of nitrogen-fixing strain N3 had the best effect,followed by the single inoculation of IAA-producing stain CDL29 and compound inoculation.In addition,inoculation of nitrogen-fixing strain N3 significantly increased soil nitrogenase activity,while inoculation of CDL29 had no significant effect on soil nitrogenase activity.As a conclusion,the single inoculation of nitrogen-fixing strain N3 could significantly promote the growth,nutrient contents in Orychophragmus violaceus,and also improve the physicochemical and biological properties of the soil.