AUTHOR=Yang Peizhou , Wu Yun , Jiang Suwei , Zheng Zhi , Hou Zhigang , Mu Dongdong , Xiao Wei , Jiang Shaotong , Yang Yung-Hun 

TITLE=Effective Expression of the Serratia marcescens Phospholipase A1 Gene in Escherichia coli BL21(DE3), Enzyme Characterization, and Crude Rapeseed Oil Degumming via a Free Enzyme Approach

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2019.00272

DOI=10.3389/fbioe.2019.00272

ISSN=2296-4185

ABSTRACT=<p>Crude oil degumming by phospholipid removal is crucial to guarantee oil quality. Phospholipase degumming could produce green vegetable oil by reducing energy consumption and protecting the environment. To develop a novel phospholipase for oil degumming, we cloned the <italic>Serratia marcescens</italic> outer membrane phospholipase A gene (<italic>OM-PLA1</italic>) and expressed its 33 KDa protein in engineered <italic>Escherichia coli</italic> BL21(DE3). OM-PLA1 activity reached 18.9 U mL<sup>−1</sup> with the induction of 0.6 mM isopropyl β-D-1-thiogalactopyranoside for 4 h. The optimum temperature and pH were 50°C and 7.5, respectively. Mg<sup>2+</sup>, Ca<sup>2+</sup>, Co<sup>2+</sup>, and Mn<sup>2+</sup> at 0.1 mM L<sup>−1</sup> significantly increased OM-PLA1 activity. The kinetic equations of OM-PLA1 and Lecitase Ultra were <italic>y</italic> = 13.7<italic>x</italic>+0.74 (K<sub>m</sub> = 18.53 mM, V<sub>max</sub> = 1.35 mM min<sup>−1</sup>) and <italic>y</italic> = 24.42<italic>x</italic>+0.58 (K<sub>m</sub> = 42.1 mM, V<sub>max</sub> = 1.72 mM min<sup>−1</sup>), respectively. The phosphorus content decreased from 22.6 to 9.3 mg kg<sup>−1</sup> with the addition of 15 units of free recombinant OM-PLA1 into 150 g of crude rapeseed oil. OM-PLA1 has the close degumming efficiency with Lecitase Ultra. The <italic>S. marcescens</italic> outer membrane phospholipase gene (OM-PLA1) possessed higher substrate affinity and catalytic efficiency than Lecitase Ultra. This study provides an alternative approach to achieve crude vegetable oil degumming with enzymatic technology.</p>