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Food & Function · 2015 ·Vol. 6 ·期 10 ·3291-3295 · IF 2.791

Enzymatic transformation of stevioside using a β-galactosidase from Sulfolobus sp.

Hui-da Wan,Yong-mei Xia

Enzymatic hydrolysis and transgalactosylation of stevioside (St) were investigated using a β-galactosidase from Sulfolobus sp. The hydrolysis yielded steviol as the main final product. Under the optimal transgalactosylation conditions, the highest conversion of stevioside was 87.3% with lactose as a donor, several galactosylated products (St-Gals) were obtained. Metal ions such as Na+, K2+, Ca2+, Ba2+, Mn2+ and Mg2+ (2 mM) did not affect the transgalactosylation activity, while Fe2+, Fe3+ and Cu2+ reduced the transgalactosylation activity of β-galactosidase to 64%, 33% and 18%, respectively.

研究领域: 生物化学 · 食品科学

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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY · 2020 ·Vol. 104 ·期 15 ·6635-6646 · IF 3.53

Thermostable arginase from Sulfobacillus acidophilus with neutral pH optimum applied for high-efficiency l-ornithine production

Huang Kai,Zhang Shurong,Guan Xiao,Liu Jing,Li Sen,Song Hongdong

This study aims to use neutral pH optimum arginase as the catalyst for high-efficiency l -ornithine production. Sulfobacillus acidophilus arginase was firstly cloned and overexpressed in Escherichia coli . The purified enzyme was obtained, and the molecular mass determination showed that this arginase was a hexamer. S. acidophilus arginase possessed similarities with the other arginases such as the conserved sequences, purification behavior, and the necessity for Mn 2+ as a cofactor. The maximum enzyme activity was obtained at pH 7.5 and 70 °C. Thermostability and pH stability analysis showed that the arginase was stable at 30–60 °C and pH 7.0–8.5, respectively. The kinetic parameters suggested that S. acidophilus arginase could efficiently hydrolyze l -arginine. Bioconversion with this neutral pH optimum arginase had the advantages of avoiding producing by-product, high molar yield, and high-level production of l -ornithine. When the bioconversion was performed with a fed-batch strategy and a coupled-enzyme system involving S. acidophilus arginase and Jack bean urease, the final production of 2.87 mol/L was obtained with only 1.72 mmol/L l -arginine residue, and the molar yield was 99.9%. The highest production record suggests that S. acidophilus arginase has a great prospect in industrial l -ornithine production.

研究领域: 生物技术 · 酶学 · 微生物学 · 生物化工

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Enzymatic transformation of stevioside using a β-galactosidase from Sulfolobus sp.

Thermostable arginase from Sulfobacillus acidophilus with neutral pH optimum applied for high-efficiency l-ornithine production