Expression Optimizing of Recombinant Oxalyl-CoA Decarboxylase in Escherichia coli

BACKGROUND: One of the most common diseases of the urinary tract is stones of this system, including kidney stones. About 70%–80% of kidney stones are calcium oxalate. Oxalyl-CoA decarboxylase is a single polypeptide included of 568 amino acids which play a key role in oxalate degradation. MATERIALS AND METHODS: The aim of current study is high-level expression of oxalyl-CoA decarboxylase in Escherichia coli BL21 (DE3). To achieve this aim, oxalyl-CoA decarboxylase gene was cloned upon pET-30a (+) with T7 promoter. The vector containing the oxalyl-CoA decarboxylase gene was transformed into E. coli and the expression of the gene was examined on a laboratory scale and fermentor. Atfirst, the effect of temperature, culture medium, and induction time on oxalyl-CoA decarboxylase expression at three levels was examined. RESULTS: The obtained data showed that the highest expression was related to the terrific broth culture medium and temperature of 32°C with an inducer concentration of 1 mM. Under this situation the ultimate cells dry weight and the final oxalyl-CoA decarboxylase expression were 2.46 g/l and 36% of total protein, respectively. Then induction time was optimized in a bench bioreactor and productivity of oxalyl-CoA decarboxylase was calculated. Under optimized condition the cell density, biomass productivity and oxalyl-CoA decarboxylase concentration reached 4.02 g/l, 0.22 g/l/h, and 0.7 g/l which are one of the highest reported rates. CONCLUSION: This study demonstrated that high levels of oxalyl-CoA decarboxylase can be achieved by optimizing the expression conditions.