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( Wenjuan Yang ),( Li Xu ),( Houjin Zhang ),( Yunjun Yan ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.11
In this study, Pseudomonas R0-14, which was isolated from Arctic soil samples, showed a clear halo when grown on M9 medium agarose plates containing olive oil-rhodamine B as substrate, suggesting that it expressed putative lipase(s). A putative lipase gene, lipR, was cloned from R0-14 by genome walking and Touchdown PCR. lipR encodes a 562-amino-acid polypeptide showing a typical α/β hydrolase structure with a catalytic triad consisting of Ser153-Asp202-His260 and one α-helical lid (residues 103-113). A phylogenetic analysis revealed that LipR belongs to the lipase subfamily I.3. LipR was successfully expressed in Escherichia coli, purified, and biochemically characterized. Recombinant LipR exhibited its maximum activity towards p-nitrophenyl butyrate at pH 8.5 and 60oC with a Km of 0.37 mM and a kcat of 6.42 s-1. It retained over 90% of its original activity after incubation at 50oC for 12 h. In addition, LipR was activated by Ca2+, Mg2+, Ba2+, and Sr2+, while strongly inhibited by Cu2+, Zn2+, Mn2+, and ethylenediaminetetraacetic acid. Moreover, it showed a certain tolerance to organic solvents, including acetonitrile, isopropanol, acetone, methanol, and tert-butanol. When algal oil was hydrolyzed by LipR for 24 h, there was an enrichment of n-3 long-chain polyunsaturated fatty acids, including eicosapentaenoic acid (1.22%, 1.65-fold), docosapentaenoic acid (21.24%, 2.04-fold), and docosahexaenoic acid (36.98%, 1.33-fold), and even a certain amount of diacylglycerols was also produced. As a result, LipR has great prospect in industrial applications, especially in food and/or cosmetics applications.
The simultaneous photocatalytic degradation of phenol and reduction of Cr(VI) by TiO2/CNTs
Langhuan Huang,Qizhong Chan,Xiaojing Wu,Houjin Wang,Yingliang Liu 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1
The main objective of this paper is to verify the potential of TiO2/CNTs in the simultaneous photocatalytic degradation of phenol and reduction of Cr(VI). From the present results it can be concluded that there is a synergistic effect between the photocatalytic degradation of phenol and reduction of Cr(VI). Under all tested conditions, the degradation of phenol and reduction of Cr(VI) were examined to follow pseudofirst-order kinetic. The rate constant of 40 mg/L of Cr(VI) was evaluated as 4.34 103 min1 in the absence of phenol, and was increased up to 9.27 103 min1 by adding 10 mg/L of phenol, and to 10.73 103 min1 by adding 15 mg/L of phenol. The presence of Cr(VI) also accelerated the degradation process of phenol, with a factor of 1.84–3 times. Such a great synergistic effect was likely to be attributed to two kinds of effects from CNTs: adsorption effect and electron trap effect. The synergistic effect induced by CNTs was also confirmed by the detection of degradation intermediates of phenol.