一株具有烟草甲毒杀作用的苏云金芽孢杆菌对烟叶的影响

Effects of Bacillus thuringiensis with toxics for Lasioderma serricorne on tobacco leaves

  • 摘要: 【目的】明确一株具有烟草甲毒杀作用的苏云金芽孢杆菌(Bacillus thuringiensisBt)在醇化过程中对烟叶的影响,为烟叶仓库中应用Bt菌剂防控烟草甲的可行性和安全性评价提供参考依据。【方法】按照0.1g Bt菌剂处理1 kg烟叶的比例作处理,以未喷施Bt菌剂的烟叶作为对照,在仓库中贮藏12个月后,每隔2个月采集醇化阶段烟叶,对总糖、还原糖、氯、总植物碱、钾、总氮和淀粉等7项常规化学成分,以及香气质、香气量、杂气、刺激性、透发性、柔细度、甜度、余味、浓度和劲头等10项感官品质进行测定和评估。同时对醇化24个月的烟叶样品使用16S rDNA扩增子测序,比较分析喷施Bt菌剂和未喷施Bt菌剂的烟叶细菌群落结构多样性变化。【结果】 Bt菌剂处理后,烟叶的7项常规化学成分均未出现显著变化(P>0.05);而感官质量的5项指标出现显著性差异(P<0.05,下同),其中香气量和杂气的评吸得分表现为处理组优于对照组,香气质、透发性和甜度的评吸得分表现为对照组优于处理组;处理组和对照组的细菌种类存在明显差异,在处理组中,纲、目、科和属分类中相对丰度最高的分别为杆菌纲(Bacilli,95.9%)、芽孢杆菌目(Bacillales,95.9%)、芽孢杆菌科(Bacillaceae,96.0%)和芽孢杆菌属(Bacillus,95.9%),而在对照组中,相对丰度最高的分别为丙型变形菌纲(Gammaproteobacteria,47.6%)、肠杆菌目(Enterobacteriales,31.3%)、肠杆菌科(Enterobacteriaceae,33.7%)和志贺氏大肠杆菌属(Escherichia-Shigella,22.9%)。处理组和对照组的Alpha多样性指数中Observed species指数和Chao1指数存在显著差异,处理组的细菌群落丰富度显著低于对照组,Beta多样性分析证明2组间的群落结构存在显著差异。【结论】使用苏云金芽孢杆菌处理后,烟叶中的细菌群落结构发生显著变化,但对烟叶化学成分和感官质量的影响较小,不造成烟叶品质的下降,说明在仓储中使用该菌株防控烟草甲的经济风险较小。

     

    Abstract: 【Objective】 To investigate effects of a strain of Bacillus thuringiensisBt)with toxics for Lasioderma serricorne on tobacco leaves during alcoholization,so as to provide reference for safety and feasibility accession by applying Bt bacterial agent to prevent and control L.serricorne in tobacco warehouses.【Method】 Tobacco leaves was treated with microbial agent at a ratio of 0.1 g Bt ratio to 1 kg tobacco and the untreated tobacco was taken as control.After 12 months of storage in warehouse,the tobacco leaves were collected every 2 months.Seven chemical indexes,including total sugar,reducing sugar,chlorine,total alkaloid,potassium,total nitrogen and starch,were detected.Ten items of sensory evaluation were also measured and accessed,namely aroma quality,aroma volume,offensive odor,irritancy,permeability,softness,sweetness,aftertaste,concentration and intensity.After alcoholization for 24 months,the bacteria diversity of tobacco leaves was analyzed using 16S rDNA amplicon sequencing to detect difference of changes in bacterial community structure diversity between the Bt treatment and control groups.【Result】 The 7 chemical indexes did not show significant change in the Bt bacterial agent treatment(P>0.05).Five sensory items significantly changed(P<0.05,the same below),in which aroma volume and offensive odor were better in the treatment group,while the sensory evaluation scores of aroma quality,permeability and sweetness were lower.The bacterial species between these two groups were significantly different.Bacterial species of treatment group and control group varied obviously: in the treatment group,among class,order,family,and genus levels,relative abundance were higher in Bacilli(95.9%),Bacillales(95.9%),Bacillaceae (96.0%),and Bacillus(95.9%),respectively;in control group,relative abundance were higher in Gammaproteobacteria (47.6%),Enterobacteriales(31.3%),Enterobacteriaceae(33.7%),Escherichia-Shigella(22.9%).Seem from Alpha diversity indexes,Observed species index and Chao1 index had significant difference,indicating that the bacterial community diversity of the treatment group was lower than that the control group.Beta diversity analysis proved that significant difference of bacterial community structure existed between the two groups.【Conclusion】 In the Bt treatment group,the bacterial community diversity in tobacco during alcoholization had significant difference,but such treatment has little change in chemical components and sensory quality of tobacco,with no quality decline found,indicating low economic risk of the applying Bt in L.serricorne control.

     

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