Expression optimizing of recombinant Oxalyl-CoA decarboxylase in Escherichia coli

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.

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. At first, the effect of temperature, culture medium, and induction time on oxalyl‑CoA decarboxylase expression at three levels was examined.

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.

This study demonstrated that high levels of oxalyl‑CoA decarboxylase can be achieved by optimizing the expression conditions.