• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.749-757
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• 2019

Nitrilase is a valuable hydrolase that catalyzes nitriles into carboxylic acid and ammonia. Its applications, however, are severely restricted by the harsh conditions of industrial reaction processes. To solve this problem, a nitrilase from Acidovorax facilis 72W was inserted into an Escherichia coli-Bacillus subtilis shuttle vector for spore surface display. Western blot, enzyme activity measurements and flow cytometric analysis results all indicated a successful spore surface display of the CotB-nit fusion protein. In addition, the optimal catalytic pH value and temperature of the displayed nitrilase were determined to be 7.0 and $50^{\circ}C$, respectively. Moreover, results of reusability tests revealed that 64% of the initial activity of the displayed nitrilase was still retained at the $10^{th}$ cycle. Furthermore, hydrolysis efficiency of upscale production of cyanocarboxylic acid was significantly higher in the displayed nitrilase-treated group than in the free group expressed by E. coli (pET-28a-nit). Generally, the display of A. facilis 72W nitrilase on the spore surface of Bacillus subtilis may be a useful method for immobilization of enzyme and consequent biocatalytic stabilization.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.307-313
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• 2010

Stanniocalcin 1 (STC1) is a glycoprotein hormone that is important in the maintenance of calcium and phosphate homeostasis in both fish and mammals. STC1 and its paralog STC2 are expressed in multiple tissues in fishes, although the physiological roles of piscine STCs are still unclear compared with those of mammals. In this study, we cloned olive flounder STC1 (ofSTC1) and ofSTC2 cDNAs into pET28a vector and used E. coli Rosetta (DE3) as the host strain for protein expression. Expression experiments were carried out using isopropyl-$\beta$-D-thiogalactoside (IPTG) and nickel affinity chromatography. We could identify the recombinant proteins as single 29.5 kDa (ofSTC1) and 33.2 kDa (ofSTC2) bands in the insoluble fraction on sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE). These results indicate that ofSTC1 and ofSTC2 were expressed as insoluble proteins in E. coli. Furthermore, the injection of ofSTC1 protein into juvenile tilapia resulted in a decrease of the serum calcium level. These results suggest that the purified fish STC1 and STC2 proteins may be used to elucidate the physiological role of STCs in fishes.