两株芽孢杆菌对花生幼苗生长及其根际土壤微生物群落结构的影响

Effects of two Bacillus spp. strains on the growth of peanut seedling and microbial community structure in rhizosphere soil

摘要:

【背景】贝莱斯芽孢杆菌(Bacillus velezensis)和坚强芽孢杆菌(Bacillus firmus)对花生的促生作用及促生机制研究尚未见报道。【目的】从微生物群落结构和土壤氮磷钾有效养分两个方面综合解析两株芽孢杆菌(贝莱斯芽孢杆菌HP9和坚强芽孢杆菌HP10)对花生的促生机制。【方法】以两株芽孢杆菌为研究对象，通过单独灌根或混合灌根盆栽花生，测定其对花生生长及根际土壤氮磷钾有效养分的影响；利用高通量测序技术分析灌根组与对照组花生根际土壤的细菌和真菌群落结构及多样性。【结果】与对照组相比，3个灌根处理组均明显促进了花生幼苗茎部的伸长及鲜重的增加，根际土壤碱解氮含量显著提高，有效磷和速效钾含量有不同程度增加。芽孢杆菌对花生根际土壤的微生物多样性无显著影响，但影响了细菌和真菌的群落结构组成。灌根处理组根际土壤的拟杆菌门及Mortierellomycota等相对丰度显著增加，在属水平上，农杆菌属、节杆菌属、芽孢杆菌属、伯克霍尔德氏菌属、黄杆菌属、Pedobacter、极地单胞菌属、假单胞菌属、鞘脂单胞菌属、寡养单胞菌属等属的相对丰度明显提高，而且无色杆菌属、短波单胞菌属、金黄色杆菌属、苍白杆菌属、鞘氨醇杆菌属和鞘氨醇盒菌属等6个细菌属仅见于3个灌根处理组中。主成分分析结果显示，与对照相比，3个灌根处理组之间的根际土壤微生物群落结构具有更高的相似性。【结论】贝莱斯芽孢杆菌HP9和坚强芽孢杆菌HP10菌株可以影响根际土壤的微生物群落结构组成，提高根际土壤功能微生物的相对丰度，从而改善土壤肥力，促进花生幼苗生长。

关键词:芽孢杆菌，花生，促生，微生物群落结构

Abstract:

[Background] The growth-promoting effects and mechanisms of Bacillus velezensis and Bacillus firmus on peanut seedlings have not been reported. [Objective] This study comprehensively explored the growth-promoting mechanism of two Bacillus strains on peanut by analyzing of rhizosphere microbial community and soil available nutrients, including nitrogen, phosphorus and potassium. [Methods] two strains (named as Bacillus velezensis HP9, Bacillus firmus HP10) were irrigated-root alone, or mixed on peanut seedling by pot experiment, their effects on peanut’s growth and available nutrients of rhizosphere soil were assessed. The community structure and diversity of bacteria and fungi in rhizosphere soil, including irrigated-root groups and control group, were analyzed by high-throughput sequencing technology, too. [Results] Comparing to control group, stem length and fresh weight of treated peanuts were obviously increased; in rhizosphere soil, alkali-hydrolyzed nitrogen contents was improved greatly, available phosphorus and potassium contents were also increased differently. When Bacillus strains were irrigated with peanut seedlings, there were no significant influence on microbial diversity of rhizosphere soil, but microbial community structure, including bacteria and fungi, were affected. At the phylum level, the relative abundance of Bacteroidetes and Mortierellomycota increased significantly in three treated groups. relative abundance of these genus, such as Agrobacterium, Arthrobacter, Bacillus, Burkholderia, Flavobacterium, Pedobacter, Polaromonas, Pseudomonas, Sphingomonas, Stenotrophomonas, were significantly improved; and six bacterial genus, including Achromobacter, Brevundimonas, Chryseobacterium, Ochrobactrum, Sphingobacterium and Sphingopyxis, were only detected in three treated groups. Using the method of principal component analysis, community structure of rhizosphere soil were found more similar in treated groups than the control. [Conclusion] Bacillus velezensis HP9 and Bacillus firmus HP10 could influence microbial community structure and increase the relative abundance of functional flora in rhizosphere soil, thus the soil fertility was improved and the growth of peanut seedling was promoted, too.

Key words:Bacillus spp., peanut, growth-promoting, microbial community structure