[目的] 菜粕有机肥(简称RC)是生物有机肥生产中常用的营养载体,本研究旨在以RC为营养源筛选可高效抑制番茄青枯病致病菌(Ralstonia solanacearum,青枯菌)的生防菌株材料,以提高生物有机肥防控番茄青枯病的效果。[方法] 分别采用营养琼脂(NA)和RC培养基,从番茄根际土中分离和筛选青枯菌拮抗菌株,并于温室条件下测定拮抗菌与RC制成的生物有机肥对番茄青枯病的防治效果。[结果] 用NA分离的菌株中NA-5在NA平板上对青枯菌的抑菌圈直径最大(29.0 mm),但在RC平板上抑菌能力微弱;而用RC分离的菌株RC-14在RC平板上对青枯菌的抑菌圈直径较大(24.0 mm)。施用NA-5和RC-14与RC二次发酵制成的生物有机肥BOF5和BOF14的生防效果显著高于单施拮抗菌,BOF14的生防效率达75.9%,显著高于BOF5。BOF14处理根际青枯菌的数量比BOF5低1个数量级。通过形态和16S rRNA基因序列同源性分析,初步鉴定RC-14菌株为土芽孢杆菌属(Geobacillus sp.)。[结论] 菌株RC-14可能通过利用RC中营养物质产生大量拮抗物质进而抑制番茄根际青枯菌的生长,降低了青枯病发病率。目前尚无Geobacillus sp.菌用于防治青枯病的报道,说明基于营养载体的筛菌思路可以获得新的生防菌资源。[Objectives] Rapeseed cake compost(RC)is an important nutrient carrier for biocontrol microorganisms in the production of bio-organic fertilizer(BOF). To enhance BOF control efficiency, herein we are aiming to screen bacterial strains that efficiently inhibit Ralstonia solanacearum, the causative agent of bacterial wilt of tomato, by using RC as the sole nutrients. [Methods] Bacterial antagonists were selected from tomato rhizosphere soils on nutrient agar(NA)and RC(8% RC in water)plates. Greenhouse assay was carried out to evaluate the efficiencies of bacterial antagonists fortified with RC on the suppression of R.solanacearum. [Results] Antagonistic strain NA-5 isolated from NA plate performed best in inhibiting R.solanacearum growth on NA plate with an inhibition zone diameter of 29.0 mm, while weak inhibition effect was observed on RC plate. Interestingly, strain RC-14 isolated from RC plates showed a remarkable inhibition zone diameter of 24 mm on RC plate. Greenhouse results showed that both NA-5 and RC-14 fortified BOF(coded as BOF5 and BOF14, respectively)significantly reduced disease incidences. BOF14 had significant higher biocontrol efficiency(75.9%)than BOF5. The R.solanacearum population in the rhizosphere soil of BOF14 treatment was significantly lower than BOF5 and other treatments(soil amended with RC, biocontrol agents or nothing). Based on the results of morphologic characteristics and analysis of 16S rRNA gene sequences, strain RC-14 was preliminarily identified as Geobacillus sp. [Conclusions] Our results clearly demonstrated that using this screen strategy can obtain novel potential biocontrol agents, as little information was found about application of Geobacillus sp.for biocontrol of R.solanacearum. Geobacillus sp.strain RC-14 might produce more antibiotics against R.solanacearum in tomato rhizosphere when RC was taken as the nutrient carrier
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