花生果腐病拮抗菌贝莱斯芽胞杆菌Hsg1949鉴定与防效

花生果腐病是由复合病原真菌引起的病害，直接严重影响花生的产量和品质。为筛选花生果腐病的生防微生物，以花生果腐病主要病原菌镰孢菌为靶标菌，采用稀释涂布平板法和平板对峙培养法，在花生根际土壤中筛选到一株对镰孢菌具有拮抗作用的生防细菌Hsg1949。经形态学观察、Biolog微生物自动鉴定系统及16S rDNA和gyrA序列构建系统发育树等综合分析，鉴定菌株Hsg1949为贝莱斯芽胞杆菌。菌株Hsg1949对3株镰孢菌分离株具有稳定的的拮抗活性，继代培养40代时，对3株镰孢菌的抑菌率分别为77.0%、69.7%和61.9%，与初始菌株F0代的抑菌活性无显著差异。其无菌上清液活性物质耐高温，耐强酸但不耐强碱，在pH 11的环境下拮抗活性显著降低。田间试验结果表明，Hsg1949菌悬液2×10⁸和5×10⁸cfu/mL可显著降低花生果腐病发病率，对花生果腐病的防治效果分别为66.54%和71.27%，与化学药剂多菌灵防效（75.11%）相当。菌株Hsg1949对花生白绢病菌、棉花立枯病菌、棉花枯萎病菌和棉花黄萎病菌也具有较强的拮抗作用，在植物真菌病害的生物防治中将具有较大的应用潜力。

Identification of Antagonistic Bacterium Bacillus velezensis Hsg1949 and Its Biocontrol Effect on Peanut Pod Rot

Pod rot caused by complex infections of a variety of pathogens leads to destructive losses of yield and quality of peanut. To obtain the biocontrol microorganism for controlling pod rot of peanut, an antagonistic bacterial strain Hsg1949 was screened from the rhizosphere soil of peanut by agar disk dilution and dual-culture assay using pathogenic fungi Fusarium spp. as indicators. Based on morphological characters, biolog identification system in combination with 16S rDNA and gyrA sequence analysis, the strain Hsg1949 was identified as Bacillus velezensis. After 40 generations of cultivation, Hsg1949 showed stable antifungal activity against three Fusarium spp. isolates, and the inhibition rates were 77.0%, 69.7 and 61.9%, respectively, without significant difference to the original generation. The cell-free supernatant also showed stable inhibitory effects against Fusarium spp. under high temperature and strong acid, however, the inhibitory activities decreased significantly when the pH value of supernatant was 11. Field trials showed that the biocontrol efficacies of Hsg1949 were 66.54% and 71.27% at concentrations of 2×10⁸ CFU/mL and 5×10⁸ CFU/mL, respectively, similar to that of carbendazim (75.11%). Also, the strain Hsg1949 exhibited antagonistic activity against four plant pathogenic fungi, including Sclerotium rolfsii, Rhizoctonia solani, Fusarium oxysporum and Verticillium dahliae. In summary, the strain Hsg1949 has excellent biocontrol characteristics and potential in biocontrol of plant diseases.