为获取新型食品级酸性菊粉酶,对前期构建的广西特色生榨米粉来源乳酸菌库进行了筛选、鉴定和酶学表征。采用终质量浓度为20 g/L菊粉作为唯一碳源的筛选培养基并结合菊粉酶酶活力测定,筛选出1株产酸性菊粉酶的乳酸菌,经过菌落形态观察及16S rDNA基因序列分析,鉴定为柠檬明串珠菌,命名为Leuconostoc citreum 1-1。以菊粉为底物开展酶学表征,结果表明,Leuconostoc citreum 1-1菊粉酶的最适温度为35 ℃,最适pH为4.0,在20~40 ℃,pH 3.5~9.0可保持80%的酶活力,薄层色谱法结果表明菊糖几乎100%被水解成果糖。该新型食品级酸性菊粉酶及其生产菌株L.citreum 1-1在高果糖浆生产等菊粉类果糖基资源利用领域具有良好的研究价值和应用潜力。
关键词：
菊粉酶; 酸性; 乳酸菌; 筛选; 菊粉
To obtain a novel acidic inulinase, an acidic inulinase producing lactic acid bacteria was screened and characterization of its enzymatic properties was conducted. By using selective medium containing inulin (20 g/L) as sole carbon source and inulin-hydrolyzing ability, a strain producing an acidic inulinase was screened out from the lactic acid bacteria collection of Guangxi's specialty raw rice flour constructed. It was identified as Leuconostoc citreum based on its morphology and 16S rDNA sequence analysis and was designated as L. citreum strain 1-1. Using inulin as substrate, inulinase produced by L. citreum 1-1 showed the maximum activity at 35℃ and pH 4.0, and maintained more than 80% of maximum activity at pH 3.5-9.0. The thin layer chromatography results showed that fructose was the sole product (100% conversion) of inulin hydrolysis by the inulinase. The novel acidic inulinase and its producing strain L.citreum 1-1 may have great scientific research value, and as well as application potentials in production of high fructose syrup and other utilizations of fructose-based resources like inulin.
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