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

【Objective】 To investigate effects of a strain of Bacillus thuringiensis（Bt）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.