Purification and characterization of a cis-epoxysuccinic acid hydrolase from Bordetella sp. strain 1–3

Development of highly efficient whole-cell catalysts of cis-epoxysuccinic acid hydrolase by surface display

Bacterial cis-epoxysuccinic acid hydrolases (CESHs) are intracellular enzymes used in the industrial production of enantiomeric tartaric acids. The enzymes are mainly used as whole-cell catalysts because of the low stability of purified CESHs. However, the low cell permeability is the major drawback of the whole-cell catalyst. To overcome this problem, we developed whole-cell catalysts using various surface display systems for CESH[L] which produces L(+)-tartaric acid. Considering that the display efficiency depends on both the carrier and the passenger, we screened five different anchoring motifs in Escherichia coli. Display efficiencies are significantly different among these five systems and the InaPbN-CESH[L] system has the highest whole-cell enzymatic activity. Conditions for InaPbN-CESH[L] production were optimized and a maturation step was discovered which can increase the whole-cell activity several times. After optimization, the total activity of the InaPbN-CESH[L] surface display system is higher than the total lysate activity of an intracellular CESH[L] overexpression system, indicating a very high CESH[L] display level. Furthermore, the whole-cell InaPbN-CESH[L] biocatalyst exhibited good storage stability at 4 °C and considerable reusability. Thereby, an efficient whole-cell CESH[L] biocatalyst was developed in this study, which solves the cell permeability problem and provides a valuable system for industrial L(+)-tartaric acid production.

Enantiomeric Tartaric Acid Production Using cis-Epoxysuccinate Hydrolase: History and Perspectives

Tartaric acid is an important chiral chemical building block with broad industrial and scientific applications. The enantioselective synthesis of l(+)- and d(−)-tartaric acids has been successfully achieved using bacteria presenting cis-epoxysuccinate hydrolase (CESH) activity, while the catalytic mechanisms of CESHs were not elucidated clearly until very recently. As biocatalysts, CESHs are unique epoxide hydrolases because their substrate is a small, mirror-symmetric, highly hydrophilic molecule, and their products show very high enantiomeric purity with nearly 100% enantiomeric excess. In this paper, we review over forty years of the history, process and mechanism studies of CESHs as well as our perspective on the future research and applications of CESH in enantiomeric tartaric acid production.

Structural insight into the catalytic mechanism of a cis-epoxysuccinate hydrolase producing enantiomerically pure d(-)-tartaric acid

Crystal structure determination and mutagenesis analysis of a cis-epoxysuccinate hydrolase which produces enantiomerically pure d(-)-tartaric acids revealed a zinc ion and essential residues in the stereoselective mechanism for the catalytic reaction of the small mirror symmetric substrate.

Characterization of a β-glucosidase from Paenibacillus species and its application for succinic acid production from sugarcane bagasse hydrolysate

In this study, a β-glucosidase from Paenibacillus sp. M1 was expressed in E. coli BL21(DE3), purified and characterized. The specific activity of purified BglA was 137.64U·mg^-1 protein with optimal temperature and pH of 50°C and 6.0. Furthermore, BglA shows excellent adaption to various environmental factors such as temperature, pH and metal ions. Engineered E. coli Suc260 was further reconstructed by overexpressing the β-glucosidase for achieving direct cellobiose utilization, which could efficiently utilize the pretreated sugarcane bagasses hydrolysate (SBH) consisting of 25.30g·L^-1 cellobiose, 9.70g·L^-1 glucose, 5.90g·L^-1 arabinose and 7.10g·L^-1 xylose. As a result, 26.50g·L^-1 and 24.30g·L^-1 succinic acid were produced by strain Suc260(pTbglA) from cellobiose and SBH with corresponding yields of 88.30% and 89.20% using dual-phase fermentation, respectively. This study indicated that incomplete enzymatic hydrolysate of SCB will be a potential feedstock for succinic acid production.