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      四川雪茄烟叶主要致霉菌拮抗芽孢杆菌的筛选及评价

      Screening and Evaluation of Antagonistic Bacillus Against Major Mold Types of Cigar Tobacco in Sichuan

      • 摘要: 为筛选对雪茄烟叶堆垛过程中致霉菌具有优良拮抗效果的细菌菌株,丰富雪茄烟叶霉变生物防控的菌种资源,从四川中烟厂房未霉变烟叶中分离、纯化细菌菌株,以实验室前期从堆垛储藏期霉变雪茄烟叶上分离的菌冠突曲霉A. cristatus、单胞共头霉S. monosporum、谢瓦曲霉A. chevalieri、短柄帚霉S. brevicaulis和蒙地曲霉A. montevidensis 5种霉变菌为靶标,通过琼脂扩散法筛选对5种病原菌均具有良好拮抗效果的菌株,通过结合形态学、生理生化和分子生物学方法鉴定拮抗细菌种类。结果表明:(1)筛选获得了3株对5种霉菌拮抗效果良好的菌株TB24016、TB24034、TB24048,经鉴定菌株TB24016和TB24048为贝莱斯芽孢杆菌(Bacillus velezensis)、TB24034为耐盐芽孢杆菌(Bacillus halotolerans);(2)3株拮抗菌株均对谢瓦曲霉拮抗作用较强,菌株TB24016、TB24034、TB24048的抑菌圈直径分别为4.49 cm、3.46 cm、2.27 cm;(3)菌株TB24016、TB24034产生蛋白酶和嗜铁素,菌株TB24048仅分泌嗜铁素,3株拮抗菌株产胞外酶的能力为TB24016>TB24034>TB24048;(4)不同拮抗菌株发酵液对不同烟叶致霉菌的抑制效果存在差异,当发酵液浓度为108 CFU/mL时,3株拮抗菌株对5种供试致霉菌抑制率均大于80%,其抑霉作用综合表现为TB24016=TB24048>TB24034。综上,结合产胞外酶能力和抑霉效果,贝莱斯芽孢杆菌TB24016对雪茄烟堆垛储藏期间优势霉变菌的拮抗效果更佳,具有作为雪茄烟叶霉变生防菌的潜力。

         

        Abstract: In order to screen bacterial strains that can efficiently antagonize major molds in the storage of cigar tobacco stacks, and to enrich the microbial resource bank for biological control of cigar tobacco leaf mildew, strains were isolated and purified from non-mildewed tobacco leaves in the workshop of Sichuan tobacco factories. Five species of mold-causing fungi, Aspergillus cristatus, Syncephalastrum monosporum, Aspergillus chevalieri, Scopulariopsis brevicaulis and Aspergillus montevidensis, which were previously isolated in the laboratory from mildewed cigar tobacco leaves during the stack storage period, were used as the target strains. Strains with broad-spectrum antagonistic activity against all five pathogenic fungi were screened using the agar diffusion method, and the antagonistic strains were identified based on morphological, physiological and biochemical, and molecular biological characteristics. The results showed that: (1) 3 strains TB24016, TB24034, TB24048 had excellent antagonistic effects on five molds. Strains TB24016 and TB24048 were identified as Bacillus velezensis, and TB24034 as Bacillus halotolerans; (2) All 3 antagonistic strains had strong antagonistic effect on A. chevalieri, with inhibition zone diameters were 4.49 cm, 3.46 cm and 2.27 cm for TB24016, TB24034 and TB24048, respectively; (3) Strains TB24016 and TB24034 produced protease and siderophore, whereas strain TB24048 produce only siderophore. The extracellular enzyme production capacity ranked as TB24016 > TB24034 > TB24048; (4) Different antagonistic strains of fermentation broth had different biocontrol effects on different molds in tobacco leaves. When the concentration of fermentation broth was 108 CFU/mL, all three antagonistic strains demonstrated inhibition rates exceeding 80% against the five tested molds, with overall antifungal performance ranked as: TB24016 = TB24048 > TB24034. In conclusion, based on the extracellular enzyme-producing ability and mold-inhibiting effect, it can be concluded that Bacillus velezensis TB24016 exhibited superior antagonistic effects against dominant mold-causing fungi in hand-rolled cigar tobacco during stack storage, and showed strong potential as a biocontrol agent for mold control in cigar tobacco leaves.

         

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