摩加夫芽孢杆菌产酶条件优化及对烟叶品质的影响

Condition Optimization of Enzyme Production from Bacillus mojavensis in Tobacco Leaf and Its Effect for Improving Tobacco Quality

纤维素、果胶、淀粉和蛋白质是烟叶中含量较高的生物大分子,对烟叶品质的影响较为显著。本研究对烟叶醇化过程中的微生物进行筛选,并对其产酶条件和作用效果进行研究,旨在发掘对烟叶品质有促进效果的功能微生物资源。研究筛选得到2-4A菌株,能够同时分泌淀粉酶、果胶酶、纤维素酶和蛋白酶,经鉴定为摩加夫芽孢杆菌(Bacillus mojavensis)。对2-4A菌株的发酵时间、发酵温度、培养基pH及接种量进行优化后,该菌株的淀粉酶、果胶酶、纤维素酶和蛋白酶的活力分别增加至41.36、3.64、5.14和72.13U/mL。用发酵液处理烟叶,能够对烟叶中的4种大分子物质进行降解,其中蛋白质的降解率达到37.8%,淀粉的降解率超过30%,果胶和纤维素的降解率均超过10%。经过2-4A菌株发酵液处理,烟叶中酮类、酸类、酯类、杂环类、醇类和醛类等香气物质的含量在整体上均得到提升,酸类和醇类物质提升最多。就单种致香物质而言,对烟叶香气有较大影响的茄尼酮含量比发酵前提高了0.51百分点,叶绿醇含量提高了15.83百分点,3-甲基丁酸含量提高了6.85百分点。摩加夫芽孢杆菌在协调烟叶化学组分和增加致香物质含量方面具有较好的效果,在提升烟叶品质方面具有应用潜力。

Cellulose,pectin,starch and protein are some macromolecules with high content in tobacco leaf,which greatly affect the quality of tobacco leaf.In this study,bacteria were isolated from mellow tobacco leaves,and their enzyme production conditions and effects were studied,providing a new theoretical basis for microbial enzyme production in tobacco leaves and improving tobacco quality.In this study,strain 2-4A was screened,which was capable of producing amylase,pectinase,cellulase and protease at the same time.The strain was identified as Bacillus mojavensis.The activities of amylase,pectinase,cellulase and protease were increased to 41.36L,3.64,5.14 and 72.13 U/mL by optimizing the fermentation time,fermentation temperature,pH of medium and inoculum volume of strain 2-4A,respectively.After 72 h treatment with fermentation solution,the four macromolecular substances in tobacco leaves were degraded.The degradation rate of protein reached 37.8%and that of starch was over 30%.The degradation effects of pectin and cellulose were slightly weaker,but both were more than 10%.The contents of ketones,acids,esters,heterocycles,alcohols,aldehydes and other aroma substances in tobacco leaves were improved by the fermentation solution of strain 2-4A.Among them,acid and alcohol substances increased the most.In terms of single substance,the content of solanidone,phytol and 3-methylbutyric acid increased by 0.51%,15.83%and 6.85%compared with that before fermentation.Bacillus mojavensis obtained in this study has the potential to be applied in improving the quality of tobacco leaves,and can be applied in the large-scale alcoholization process of tobacco leaves in the future.