Su Hongfei, Mai Zhimao, Yang Jian, Xiao Yunzhu, Tian Xinpeng, Zhang Si
Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, P.R. China.
University of Chinese Academy of Sciences, Beijing 100049, P.R. China.
J Microbiol Biotechnol. 2016 Jun 28;26(6):1067-76. doi: 10.4014/jmb.1511.11068.
The gene encoding lipase (Lip98) from Aeromicrobium sp. SCSIO 25071 was cloned and functionally expressed in Escherichia coli. Lip98 amino acid sequence shares the highest (49%) identity to Rhodococcus jostii RHA1 lipase and contains a novel motif (GHSEG), which is different from other clusters in the lipase superfamily. The recombinant lipase was purified to homogeneity with Ni-NTA affinity chromatography. Lip98 showed an apparent molecular mass of 30 kDa on SDS gel. The optimal temperature and pH value for enzymatic activity were recorded at 30°C and 7.5, respectively. Lip98 exhibited high activity at low temperatures with 35% maximum activity at 0°C and good stability at temperatures below 35°C. Its calculated activation energy was 4.12 kcal/mol at the low temperature range of 15-30°C. Its activity was slightly affected by some metal ions such as K(+), Ca(2+), and Na(+). The activity of Lip98 was increased by various organic solvents such as DMSO, ethanol, acetone, and hexane with the concentration of 30% (v/v) and retained more than 30% residual activity in neat organic solvent. The unique characteristics of Lip98 imply that it is a promising candidate for industrial application as a nonaqueous biocatalyst and food additive.
克隆了来自嗜气微菌属菌株SCSIO 25071的脂肪酶（Lip98）编码基因，并在大肠杆菌中进行了功能表达。Lip98氨基酸序列与约氏红球菌RHA1脂肪酶具有最高（49%）的同一性，且包含一个新基序（GHSEG），这与脂肪酶超家族中的其他簇不同。通过镍-氮三乙酸亲和层析将重组脂肪酶纯化至同质。Lip98在SDS凝胶上的表观分子量为30 kDa。酶活性的最佳温度和pH值分别记录为30°C和7.5。Lip98在低温下表现出高活性，在0°C时具有35%的最大活性，并且在低于35°C的温度下具有良好的稳定性。在15 - 30°C的低温范围内，其计算得到的活化能为4.12千卡/摩尔。其活性受到一些金属离子如K(+)、Ca(2+)和Na(+)的轻微影响。Lip98的活性在30%（v/v）浓度的二甲基亚砜、乙醇、丙酮和己烷等各种有机溶剂中有所提高，并且在纯有机溶剂中保留了超过30%的残余活性。Lip98的独特特性表明它作为非水生物催化剂和食品添加剂在工业应用中是一个有前途的候选者。
