黄芪根腐病拮抗芽孢杆菌的筛选鉴定及其对根围细菌群落的影响

Screening and identification of antagonistic Bacillus against Astragalus membranaceus root rot and its effect on microorganism community in root zone soil

根腐病是严重危害黄芪产业化生产的一类土传病害。该文以山西省黄芪根腐病的优势致病菌Fusarium solani和F.acuminatum为靶标,筛选具有良好抑菌防病效果的生防芽孢杆菌,并测定其对黄芪根围土壤细菌群落的影响,以期为生防制剂的后续开发提供物质基础和理论依据。试验采用平皿对峙拮抗、发酵液抑菌活性测定、菌丝生长抑制、以及离体防病效果测定的方法,对分离自黄芪根围土壤中的芽孢杆菌进行多重筛选,并对获得的目标拮抗芽孢杆菌SXKF16-1进行形态学、生理生化特性、16S r DNA序列鉴定,同时采用DGGE技术分析其对土壤细菌群落的影响。结果显示,菌株SXKF16-1抑菌效果显著,其无菌发酵滤液对F.solani,F.acuminatum的抑菌圈直径分别为(25.90±1.18),(25.86±1.85)mm,且持效性良好;离体防病试验中,F.solani,F.acuminatum侵染后保护性处理和治疗性处理的病情指数分别是(37.50±8.58),(41.67±4.90)和(25.00±8.33),(38.89±9.62),与对照相比均差异显著(P<0.05)。该菌株鉴定为萎缩芽孢杆菌Bacillus atrophaeus,其发酵液施入土壤后,明显提高了土壤中的细菌多样性。B.atrophaeus SXKF16-1能够有效拮抗根腐病病原菌,并且提高黄芪根围土壤的细菌多样性,具有开发为专用生防制剂的潜力。

The Astragalus membranaceus root rot disease,a soil-borne disease,has become increasingly severe in Shanxi province.This study was aimed at getting antagonistic Bacillus with excellent bio-control effects,and determining its effects on bacterial communities in root zone soil.With Fusarium solani and F.acuminatum as the target,antagonistic Bacillus was selected through such tests as living body dual culture,antifungal effect of bacteria-free filtrate,mycelia growth inhibition in vitro and control effect in detached roots,and identified with morphology,physio-biochemical characteristics and 16 S r DNA sequence analysis.The results showed that the Bacillus strain SXKF16-1 had obvious antifungal effect.The diameter of inhibition zone of its bacteria-free filtrate to F.solani and F.acuminatum was(25.90±1.18)mm and(25.86±1.85)mm respectively,and showed a lasting inhibition effect to mycelia growth.The disease index of the protective treatment and that of the cure treatment in detached roots test to F.solani and F.acuminatum were(37.50±8.58),(41.67±4.90)and(25.00±8.33),(38.89±9.62)respectively,both being significantly different(P<0.05)from that of the control.The strain SXKF16-1 was identified as Bacillus atrophaeus.The B.atrophaeus SXKF16-1 showed significantly inhibition effect to pathogen causing root rot and could increase the bacterial diversity in root zone soil.It has potential to be developed as a special biocontrol agent.