Balaji Lavanya, Jayaraman Gurunathan
School of Bio Sciences and Technology, VIT University, Vellore 632014, India.
School of Bio Sciences and Technology, VIT University, Vellore 632014, India.
Int J Biol Macromol. 2014 Jun;67:380-6. doi: 10.1016/j.ijbiomac.2014.03.050. Epub 2014 Apr 2.
Lipase producing halo tolerant Bacillus sp. VITL8 was isolated from oil contaminated areas of Vellore. The identity of the organism was established by 16S rDNA sequence, in addition to the morphological and biochemical characterization. The purified enzyme (22kDa, 8680U/mg) exhibited optimal activity at pH 7.0 and 40°C and retained more than 50% of its activity in the NaCl concentration range of 0-3.0M, pH 6.0-10.0 and 10-60°C. Secondary structure analysis, using circular dichroism, revealed that the enzyme is composed of 38% α-helix and 29% β-turns. The lipase activity significantly increased in the presence of (1mM) Mn(2+) (139%), Ca(2+) (134%) and Mg(2+) (130%). Organic solvents such as butanol and acetonitrile (25%, v/v) enhanced the activity whereas DMSO (25% v/v) retained the activity. The Km of enzyme-p-Nitrophenyl palmitate complex was determined to be 191μM with a Vmax of 68μM/mg/min. Though halotolerant Bacillus sp. has been explored for hydrocarbon degradation, to our knowledge this is the first report on the lipase activity of the isolate. The characteristics of the enzyme presented in this report, imply broader operational range of the enzyme and therefore could be suitable for many of the industrial chemical processes.
从韦洛尔的油污区域分离出了产脂肪酶的耐盐芽孢杆菌VITL8。除了形态学和生化特征鉴定外，还通过16S rDNA序列确定了该菌株的身份。纯化后的酶（22kDa，8680U/mg）在pH 7.0和40°C时表现出最佳活性，并且在0 - 3.0M的NaCl浓度范围、pH 6.0 - 10.0以及10 - 60°C条件下能保留超过50%的活性。利用圆二色性进行的二级结构分析表明，该酶由38%的α - 螺旋和29%的β - 转角组成。在（1mM）Mn(2+)（139%）、Ca(2+)（134%）和Mg(2+)（130%）存在时，脂肪酶活性显著增加。诸如丁醇和乙腈（25%，v/v）等有机溶剂可提高活性，而DMSO（25%，v/v）能保持活性。酶与对硝基苯基棕榈酸酯复合物的Km值测定为191μM，Vmax为68μM/mg/min。虽然已对耐盐芽孢杆菌进行了烃类降解方面的研究，但据我们所知，这是关于该分离株脂肪酶活性的首次报道。本报告中呈现的酶的特性表明该酶具有更广泛的操作范围，因此可能适用于许多工业化学过程。
