Abstract: At present, the commercial catalases mostly come from animal liver and Aspergillus niger fermentation, but these enzymes usually have poor thermal stability, low enzyme activity and high price. In order to solve this problem, a strain of Pseudomonas Stutzeri S12 with the high-level activity of catalase was isolated from landfill leachate. Through whole genome sequencing and gene identification, the gene katE encoding catalase in this strain was found, and it was heterologously expressed and purified in E. coli BL21 (DE3). KatE’s optimal temperature was 35 ℃, the optimal pH was 8.0, and its activity couldreach to 1 349 U·mg-1. The enzyme had a wide range of temperature adaptability in the range of 10 ～ 40 ℃. KatE had good thermal stability. After being treated at 50 ℃ for 5 h, 70% enzyme activity was remained, and after being incubated at 60 ℃ for 2 h, 50% enzyme activity was remained. The Km and Vmax values were 100.5 mmol·L-1 and 16 666 μmol·L-1·min-1, respectively. The enzyme activity was better under medium and low temperature conditions, showed good thermal stability and high enzyme activity, which provided a new material for the development of new commercial catalase.

Key words: Pseudomonas Stutzeri, catalase, catalase characterization, heterologous expression

摘要： 商品过氧化氢酶目前大部分来源于动物肝脏和黑曲霉发酵，但是这些酶通常热稳定性不好、酶活力低且售价高。为了解决这一问题，从垃圾渗滤液中筛选出来一株高产过氧化氢酶的菌株Pseudomonas stutzeri S12，通过全基因组测序和基因鉴定发现了该菌株中编码过氧化氢酶的基因katE，将其在E.coli BL21（DE3）中异源表达和纯化。KatE的最适温度为35 ℃，最适pH为8.0，酶比活可达到1 349 U·mg^-1，该酶在10～40 ℃范围内的酶活力较高，具有较为广泛的温度适应性。 KatE具有较好的热稳定性，50 ℃处理5 h还剩余70%的酶活，60 ℃孵育2 h后剩余酶活仍有50%。其动力学性质Vmax为16 666 μmol·L^-1·min^-1，Km为100.5 mmol·L^-1。该酶在中低温条件下酶活较好，热稳定性较好，且酶活力较高，为开发新型商品过氧化氢酶提供了新的材料。

关键词: Pseudomonas stutzeri, 过氧化氢酶, 酶学特性, 异源表达