3株甘蔗内生芽孢杆菌的抑菌促生活性评估

Evaluation of Antibacterial and Growth-promoting Activity of Three Endophytic Bacillus from Sugarcane

【目的】测试3株甘蔗内生细菌的抗病促生长活性,并确定优良菌株的分类学地位,为后续甘蔗生防菌剂的研究与开发提供理论依据与材料。【方法】以分离自甘蔗栽培种闽糖69-421和滇蔗01-58的3株芽孢杆菌P8、Q2和P7为研究对象,测定其广谱抑菌活性和促生长活性指标;检测菌株的常规生理生化指标,对菌株16S rRNA和GyrA两个看家基因进行测序,采用MEGA软件邻接法对3株菌株进行聚类分析。【结果】3株菌株对串珠镰刀菌(Fusarium moniliforme)、烟草炭疽菌(Colletotrichum micotianae Averna)、立枯丝核菌(Rhizoctonia solani)、禾谷镰孢菌(F.graminearum)、大斑凸脐蠕孢菌(Exserohilum turcicum)和玉蜀黍离蠕孢菌(Bipolaris maydis)均具有良好的抑制效果。菌株Q2对玉米小斑病菌的抑制效果最好,抑制率达到81.60%,对其余病原菌抑制率也达到61%以上;其嗜铁素合成能力强于P8和P7;其无机磷利用能力强于P8和P7,可溶性磷含量达166.95 mg/L;培养3 d时,Q2的纤维素酶活性为5.22 U/mL,活性较高,产生纤维素的能力较强。经鉴定,菌株Q2为枯草芽孢杆菌。【结论】甘蔗内生菌枯草芽孢杆菌Q2具有良好的广谱抑菌活性,其嗜铁素、溶磷和纤维素酶活性高,具有进一步开发为抗病促生长生物菌剂的潜力。

[Purpose]To test the resistance and growth-promoting activity of three strains of endophytic bacteria in sugarcane,and to determine the taxonomic status of superior strains,so as to provide theoretical basis and material for the subsequent research and development of biocontrol agents in sugarcane.[Methods]Three strains of Bacillus spp.P8,Q2 and P7 isolated from sugarcane cultivars Mintang 69-421 and Dianzhen 01-58 were used as research objects,and their broad-spectrum antibacterial activity and growth-promoting activity indexes were determined.By routine physiological and biochemical indicators and sequencing of 16S rRNA and GyrA,cluster analysis of the three strains was performed by MEGA software adjacency method.[Results]The effects of three strains on Fusarium moniliforme,Colletotrichum micotianae Averna,Rhizoctonia solani and F.graminearum,Exserohilum turcicum and Bipolaris maydis were investigated and all of them showed good inhibitory.The strain Q2 had the best inhibitory effect on B.maydis,the inhibitory rate was 81.60%,and the inhibitory rate on other pathogens was more than 61%.Its ferriphilin synthesis abil-ity was stronger than P8 and P7;the utilization capacity of inorganic phosphorus was stronger than P8 and P7,and the soluble phosphorus content reached 166.95 mg/L.After three days of culture,cellu-lase activity of Q2 was 5.22 U/mL,with high activity and strong ability to produce cellulose.Q2 was identified as Bacillus subtilis.[Conclusion]The endophytic B.subtilis Q2 of sugarcane has good broad-spectrum antibacterial activity,and has high activities of ferritin,phosphor and cellulase,which has the potential for further development as a disease-resistant and growth-promoting biological agent.