一株产热稳定性脂肪酶莱茵海默氏菌（Rheinheimera sp.）NT-1的分离及其酶学性质分析

采用吐温-80平板法从农田土壤中筛选出一株产热稳定脂肪酶的菌株。根据生理生化和16S rDNA序列同源性分析，属于莱茵海默氏菌（Rheinheimera sp.），并命名为莱茵海默氏菌（Rheinheimera sp.）NT-1。该菌的最佳产酶温度、pH、盐度、装液量和培养时间分别为20℃、pH 8.0、8.1%（m/v）、30 mL和24 h。用Box-Behnken实验设计对脂肪酶生产进行优化，通过影响因子设计和响应面分析得到最优生产参数：pH 8.8，盐度0.78%（m/v），温度32℃，最大酶活达780±4.5 U/mL。该脂肪酶的最适温度60℃。在温度为20~70℃和pH 7~10的范围内，脂肪酶活性较高，属于热稳定性和碱性脂肪酶。该脂肪酶能催化合成脂肪酸乙酯如油酸乙酯、棕榈酸乙酯、亚油酸乙酯，表明在生物转化领域有着潜在的应用。

Isolation and Characterization of an Effective Thermostable Lipase Producing Rheinheimera sp. NT-1

An effective lipase-producing bacterium was isolated from soil samples of farmland in Lanzhou China, using Tween 80 agar plates. It was identified to belong to Rheinheimera sp. based on morphological and biochemical tests and 16S rDNA sequence analysis and was designated as Rheinheimera sp. NT-1. The cultivating conduction for the lipase production of Rheinheimera sp. NT-1 was studied in this paper. The optimum temperature, pH, salinity, liquid volume and incubation time for lipase production was 20℃, pH 8.0, 8.1%(m/v), 30 mL and 24 h, respectively. A Box-Behnken experimental design was used to optimize the lipase production. The optimization process parameters were pH 8.8 and salinity of 0.78% (m/v) at 32℃ through factorial design and RSM analysis. The highest lipase production was 780±4.5 U/mL. The optimum temperature of the lipase was 60℃. The lipase showed relatively high specific activity at the range of 20~70℃ and pH 7~10. It might be a thermo stable and alkaline lipase. The enzyme could catalyze the synthesis of fatty acid ethyl esters such as ethyl oleate, ethyl palmitate and ethyl linoleate, which had potential applications in the biotransformation.