甲基营养型芽孢杆菌对西瓜枯萎病菌拮抗作用的研究

Study on rhizospheric microflora of Bacillus methylotrophicus Strain Antagonistic against Watermelon Fusarium Wilt Disease

在西瓜枯萎病重病园区,从生长正常西瓜根际分离获得一株细菌XG-1。经对峙培养和孢子萌发抑制测定,XG-1对西瓜枯萎病菌菌丝生长、孢子萌发具有良好抑制效果。XG-1明显抑制西瓜枯萎病菌菌丝向四周均匀扩展,抑菌带宽度平均为0.6 cm。XG-1培养液处理病原菌菌丝体和分生孢子培养液后,可使尖孢镰刀菌小型分生孢子由椭圆形致畸膨大数倍后成球形,使病原菌大型分生孢子由镰刀形畸变成葫芦串形,使菌丝体致畸膨大成串珠状,同时使分生孢子在合适的条件下不能萌发或萌发后生长缓慢,产生很短的芽管,而失去侵染力。田间小区试验表明,生防菌灌根处理西瓜苗死亡率为10%,相比对照处理的24.44%,能显著降低植株发病率。结合形态学、生理生化特征和16S r DNA序列分析将XG-1鉴定菌株为甲基营养型芽孢杆菌(Bacillus methylotrophicus)。

A biocontrol strain XG-1 was obtained from the soil rhizospheric microflora of healthy watermelon in the field heavily infected with Fusarium oxysporum f. sp. niveum （FON）. XG-1 effectively inhibited mycelium growth and conidia germination via dual-culture amd inhibition test. The dual culture FON with XG-1 resulted in good inhibitive zones of 0.6 cm. Culture supernatant of XG-1 deformed some cells of hyphae and spore to be strings of beads or abnormally spherical spore of pathogens of watermelon. Efficacy of strain XG-1 to control the wilt disease was 10% in pot trials, and significantly reduced the incidence of watermelon seedlings. Strain XG-1 was identified as Bacillus methylotrophicus according to its characteristics in morphology and molecular biology analysis according to morphological, physio-biochemical tests and 16S rDNA sequence analysis.