产半纤维素酶的苔藓放线酸菌对烟草上部叶品质的影响

Effect of a hemicellulase-producing strain of Actinacidiphila bryophytorum on the quality of upper tobacco leaves

摘要:

目的 提高烟草上部叶片的整体品质。方法 从烟草土壤中分离到一株产半纤维素酶的菌株，鉴定为苔藓放线酸菌(Actinacidiphila bryophytorum)。对该菌株进行培养条件优化后制成粗酶液喷施于烟草上部叶，对处理后的烟叶进行物理特性、化学成分等方面的效果评价。结果 该菌株的最佳发酵条件为接种量4%，培养温度30 ℃，培养基pH 6.0，培养时间36 h。将不同浓度的酶制剂(50、100、150、200、250 U/mL)喷施于烟草上部叶片表面，评价其外观质量、常规化学成分、木质纤维素含量和感官评价。结果表明，150 U/mL酶制剂处理效果最优。与对照组相比，烟叶在成熟度、颜色、特性和结构方面均有改善，总分提高5.15分。总糖和还原糖含量分别提高了29.87%和35.77%，烟碱含量降低了16.10%。纤维素、半纤维素和木质素含量分别下降16.37%、20.22%和17.13%。增加了香气特性，减少了杂气。结论 利用苔藓放线酸菌S2菌株发酵制备的酶制剂，改善了烟叶外观品质，提高了水溶性总糖和还原糖含量，降低了木质纤维素含量，改善了烟叶的香气、烟味和口感，对烟叶品质有所改善。

关键词:烟叶质量;半纤维素酶;外观质量;化学成分;感官评价

Abstract:

Objective To improve the overall quality of upper tobacco leaves.Methods We isolated a hemicellulase-producing bacterium from tobacco soil and identified it as Actinacidiphila bryophytorum. After optimizing the culture conditions of this strain, we prepared the crude enzyme liquid, which was sprayed on upper tobacco leaves. The physical properties and chemical composition of the treated tobacco leaves were then evaluated.Results The optimal fermentation conditions for the strain were an inoculation rate of 4%, pH 6.0, and incubation at 30 ℃ for 36 h. Enzyme preparations of different concentrations (50, 100, 150, 200 and 250 U/mL) were then sprayed on the surface of upper tobacco leaves, and the appearance quality, conventional chemical composition, lignocellulose content, and sensory scores of the tobacco leaves were evaluated. The results indicated that treatment of the enzyme preparation at 150 U/mL performed better than other treatments. Compared with the control group, the 150 U/mL treatment increased the overall score for the appearance quality (maturity, color, characteristics, and structure) of tobacco leaves by 5.15 points. Additionally, this treatment increased the total sugar content and reducing sugar content by 29.87% and 35.77%, respectively. Meanwhile, it decreased the content of nicotine, cellulose, hemicellulose, and lignin by 16.10%, 16.37%, 20.22%, and 17.13%, respectively. Furthermore, the aroma characteristics were enhanced, and off-flavors were reduced.Conclusion The enzyme preparation produced by the fermentation of A. bryophytorum S2 improves the appearance quality, increases the soluble total sugar and reducing sugar content, and reduces the lignocellulose content of tobacco leaves, thus improving the overall quality of tobacco leaves.

Key words:tobacco leaf quality;hemicellulase;appearance quality;chemical composition;sensory evaluation