雪茄烟叶单宁降解菌的筛选、鉴定及发酵工艺优化

Screening and identification of tannin-degrading bacteria to optimize fermentation of cigar tobacco

为降低雪茄烟叶中的单宁含量(质量分数),减少雪茄烟叶苦味,改善烟叶品质,从雪茄烟叶表面筛选得到16株对烟叶中单宁有降解效果的细菌菌株,通过测定单宁酶活力选出产酶能力最强的菌株B-3,经鉴定该菌株为成团泛菌(Pantoea agglomerans)。选择不同种类的碳源、氮源和无机盐并设置不同质量浓度梯度,筛选菌株B-3的最优产酶培养基(蔗糖15.45 g/L、酵母膏17.00 g/L、NaCl 4.94 g/L)。产酶培养基优化后菌株B-3所产酶液单宁酶活力高达55.83 U/mL,相比产酶基础培养基提高121.28%。将该酶液用无菌水稀释成单宁酶活力为5.58 U/mL的稀释酶液,并用稀释酶液对印度尼西亚雪茄烟叶进行发酵处理。当稀释酶液添加量为雪茄烟叶质量的25%且在45℃条件下发酵7 d后,雪茄烟叶的单宁降解率为39.69%,烟叶的苦味和杂气减少。

In order to reduce tannin contents(mass fraction)and bitterness of cigar tobacco and to improve the overall leaf quality,16 tannin-degrading bacterial strains were screened from the surface of cigar tobacco leaves.Among them,strain B-3 had the strongest enzyme-producing ability according to the tannase activity assay and was identified as Pantoea agglomerans.Different types of carbon sources,nitrogen sources,and inorganic salts were selected and different concentration gradients were set to screen the optimal enzyme-producing medium for strain B-3.The tannase activity of the enzyme solution produced by strain B-3 on the optimal enzyme-producing medium(sucrose 15.45 g/L,yeast extract 17.00 g/L,NaCl 4.94 g/L)reached 55.83 U/mL,which was 121.28%higher than that on the basic enzyme-producing medium.The enzyme solution was diluted with sterile water to obtain a tannase activity of 5.58 U/mL.When Indonesian cigar tobacco leaves were fermented with the diluted enzyme solution at a mass ratio of 25%and at 45℃for 7 days,the tannin degradation rate was 39.69%,and the bitterness and offensive odor of the leaves were reduced.