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함시온,한영훈,김상현,서민주,조장연,이홍주,박시형,박경문,안정오,주정찬,BHATIA SHASHI KANT,양영헌 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.10
Whole-cell systems offer many benefits for biochemical production, such as relatively easy enzyme control and higher tolerance toward harsh environments, than purified enzymes. These systems can be applied to many bioconversion reactions, but they sometimes require cofactor regeneration units to support reactions at high substrate concentrations. Here, we examined L-glutamate oxidase (GOX) from Streptomyces sp. X119-6, which produces α-ketoglutarate (α-KG) from L-glutamate, and catalase (KatE) from Escherichia coli, which removes hydrogen peroxide generated by GOX. After optimizing the expression vector, pH, strains, culture conditions, and isopropyl β-D-1-thiogalactopyranoside concentration, we compared their efficiency to that of a previously reported GOX from Streptomyces mobaraensis. Our results indicated that GOX from Streptomyces sp. X119-6 and KatE increased α-KG production by 2.76-fold. This GOX required high levels of α-KG as an amino donor to convert 5-aminovaleric acid to glutaric acid. Performing the reaction at pH 8 enabled us to avoid the exogenous addition of catalase, but severe substrate inhibition was observed, resulting in the production of 287mM glutaric acid. This α-KG regeneration system has potential for improving production in various aminotransferase systems.
이선미,이홍주,김상현,서민주,조장연,함시온,GURAVRANJITGAJANAN,이상현,Shashi Kant Bhatia,양영헌 한국생물공학회 2022 Biotechnology and Bioprocess Engineering Vol.27 No.2
L-pipecolic acid (L-PA) is a key chiral intermediate in the synthesis of many important drugs. However, there is a lack of research on the efficient extraction and purification process for L-PA. Here, eleven different organic solvents were evaluated for selective extraction of L-PA by physical extraction. Among these solvents, methyl ethyl ketone (MEK) showed the highest extraction yield of LPA, and analysis of the linear solvation energy relationship between the solvents showed that MEK was the most suitable solvent for L-PA extraction. The highest extraction yield of L-PA was 37% under optimal conditions (pH 6, 20oC, 30 min and ratio of 1). Furthermore, the repetitive extraction of L-PA from bioconversion solution was also investigated. The MEK gave high purity of L-PA (93.1% and 22.8% yield) from the bioconversion mixture. Our study is the first approach to show easy recovery of L-PA by liquid-liquid extraction and the application of MEK extraction method to L-lysine bioconversion mixture.