Biotechnology Bulletin ›› 2022, Vol. 38 ›› Issue (2): 105-112.doi: 10.13560/j.cnki.biotech.bull.1985.2021-0349

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Effects of a Xylanase-producing Bacillus cereus on the Composition and Fermented Products of Cigar Leaves

LI Zhi-hao1,2,3(), ZHANG Ge3, MO Zhi-jie2, DENG Shuai-jun2, LI Jia-yi2, ZHANG Hai-bo3, LIU Xiao-hui4(), LIU Hao-bao1,2()   

  1. 1. College of Agriculture,Qingdao Agricultural University,Qingdao 266109
    2. Key Laboratory of Tobacco Biology and Processing,Tobacco Research Institute of Chinese Academy of Agricultural Sciences,Qingdao 266101
    3. CAS Key Laboratory of Bioenergy,Qingdao Institute of Bioenergy and Bioprocess Technology,Chinese Academy of Sciences,Qingdao 266101
    4. Shenzhen Tobacco Industry Co.,Ltd.,Shenzhen 518000
  • Received:2021-03-20 Online:2022-02-26 Published:2022-03-09
  • Contact: LIU Xiao-hui,LIU Hao-bao E-mail:lzh1996work@163.com;xhliu_sz@163.com;liuhaobao@caas.cn

Abstract:

Hemicellulose in cigar wrapper leaves plays an important role in the characteristics of vein and leaf toughness. The thick vein and high hemicellulose content in cigar leaves lead to poor toughness and usability of cigar wrapper. A xylanase-producing strain Bacillus cereus was preliminary screened in the previous stage of our lab,it was found that its tolerance to nicotine was fine. Then the liquid fermentation experiment was used to determine the optimal fermentation condition when the strain was using cigar leaves as nutrient sources to produce xylanase. Under the optimal fermentation condition,the degradation effect of hemicellulose in the tobacco leaves was measured,and finally the effects of the strain on the composition and contents of aroma materials in the cigar leaves were compared and analyzed. The results showed that the growth of the strain was inhibited little in the medium of ≤ 1.0 g/L nicotine,i.e.,the strain had the favorable tolerance to nicotine. When the initial pH of the culture medium was 6.7,the inoculation amount was 5%,and the concentration of cigar leaf substrate was 20 g/L,and fermentation for 24 h,the xylanase production of the strain was the highest,reaching(4.04±0.18)U/mL. Under the optimal fermentation conditions,the hemicellulose content in the cigar leaves was 3.38%,which decreased by 6.63%,and the cellulose content was 10.54%,which decreased by 8.19%, meanwhile,the contents of cellulose and hemicellulose in the cigar leaves decreased under the fermentation. The analysis of aroma materials in the fermented products revealed that phyllol alcohol(2.85%),oleic acid(0.62%),n-hexadecane(1.75%)and hentriacontane(14.47%)were enhanced after fermentation by the strain. It is expected that B. cereus can be used in the solid fermentation of leaves for cigar wrapper to improve the physical properties of tobacco leaves,thus laying a foundation for the development and utilization of this strain.

Key words: leaf for cigar wrapper, xylanase, Bacillus cereus, fermentation, hemicellulose