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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,从四川中烟长城雪茄厂未霉变烟叶中分离、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冠突曲霉Aspergillus cristatus、单孢共头霉Syncephalastrum monosporum、谢瓦曲霉A. chevalieri、短柄帚霉Scopulariopsis brevicaulis和蒙地曲霉A. montevidensis 等5种霉变菌为靶标,通过琼脂扩散法筛选对5种病原真菌均具有良好拮抗效果的细菌菌株,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B. 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、3.46、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对雪茄烟叶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 Great Wall Cigar Factory, China Tobacco Sichuan Industrial Co., Ltd. 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 were as follows (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 (TB24016, TB24034 and TB24048) exhibited strong antagonistic effects against A. chevalieri, with inhibition zone diameters of 4.49, 3.46 and 2.27 cm, respectively; (3) Strains TB24016 and TB24034 produced protease and siderophore, whereas strain TB24048 produced only siderophore. The extracellular enzyme production capacity ranked as TB24016 > TB24034 > TB24048; (4) The inhibitory effects of fermentation broths from different antagonistic strains varied among the molds isolated from 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, Bacillus velezensis TB24016 exhibited superior antagonistic effects against dominant mold-causing fungi in cigar tobacco during stack storage, demonstrating strong potential as a biocontrol agent for mold control in cigar tobacco leaves.

         

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