文心兰炭疽病生防潜力菌的鉴定及其抑菌性的测定

为获得对文心兰（Oncidium hybridum）炭疽病具有生物防治潜力的菌株，前期从健康文心兰“博大1号”叶片中分离得到1株内生菌株WB75，通过平板对峙法和发酵液抑菌性判定该菌具有防治炭疽病的生防潜力。平板对峙结果表明，菌株WB75对胶孢炭疽菌的抑制率为58.79%。菌株WB75的发酵原液和高温处理后的发酵液对胶孢炭疽菌的抑制率分别为77.69%和41.26%，由此推测WB75抑菌活性物质的热稳定性较差。菌株WB75对8种（热带生炭疽菌Colletotrichum tropicicola、鹰嘴豆枯萎镰刀菌Fusarium delphinoides、腐皮镰孢菌Fusarium solani、隔孢假壳科真菌Paraconiothyrium thysanolaenae、尖孢镰刀菌Fusarium oxysporum、画眉草弯孢菌Curvularia eragrostidis、芒果球座菌Guignardia mangiferae、巨座壳科真菌Muyocopron alcornii） 文心兰致病菌（12株）均有较好的抑制作用，抑制率38.42%～91.53%。通过生理生化特性和16S rDNA、gyrA和gyrB多基因序列比对，鉴定菌株WB75为解淀粉芽孢杆菌（Bacillus amyloliquefaciens）。这株解淀粉芽孢杆菌是对文心兰病害具有拮抗作用的潜在生防菌。

Identification of biocontrol potential microorganism and assessment of its antimicrobial activity against Oncidium hybridum Anthracnose

Endophytes were isolated from healthy Oncidium hybridum leaves. An endophyte strain WB75 was identified as a potential biocontrol agent via plate confrontation analysis by using Colletotrichum gloeosporioides as reference pathogen which causes O. hybridum anthracnose. The plate confrontation showed the endophyte strain WB75 had an inhibition rate of 58.79% against C. gloeosporioides, and that its fermentation broth and autoclaved fermentation broth had inhibition rates of 77.69% and 41.26% against C. gloeosporioides, respectively. It was speculated that the endophyte strain WB75 had poor thermal stability. The antagonism of the endophyte strain WB75 against other pathogens were detected by using the plant confrontation, and these pathogens included 12 strains of 8 species of pathogens, Colletotrichum tropicicola, Fusarium delphinoides, Fusarium solani, Paraconiothyrium thysanolaenae, Fusarium oxysporum, Curvularia aeragrostidis, Guignardia mangiferae, Muyocopron alcornii, which were isolated from different parts of O. hybridum. The plate confrontation showed that the inhibition rates of the endophyte strain WB75 against the 12 strains of pathogens ranged from 38.42 to 91.53%. The endophyte strain WB75 was identified as Bacillus amyloliquefaciens through its physiological-biochemical characteristics and the sequence analysis of its 16s rDNA, and gyrA and gyrB genes. It is concluded that B. amyloliquefaciens is a species of bacteria with potential biocontrol activity against Oncidium hybridum anthracnose.