• Journal of Applied Biological Chemistry
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• v.62 no.4
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• pp.361-366
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• 2019

Isorhamnetin 3-O-glucoside, a member of the flavonol group, has been reported to be effective for inflammatory and ulcer, as well as to alleviate diabetic complications such as neuropathy, nephropathy and retinopathy. Isorhamnetin 3-O-glucoside has been extracted from several plants. Biotransformation is a valuable tool, which is used to produce value-added chemicals with inexpensive compounds. To synthesis isorhamnetin 3-O-glucoside from quercetin, two genes (PGT E82L and ROMT-9) were introduced into Escherichia coli, respectively. In order to synthesis isorhamnetin 3-O-glucoside from quercetin, a co-culture fermentation system was developed by optimizing the medium and temperature for biotransformation, the cell mix ratio, Isopropyl-β-ᴅ-thiogalactoside induction time, and quercetin feed concentration. Finally, isorhamnetin 3-O-glucoside was biosynthesized up to 181.2 mg/L under the optimized biotransformation condition, which was higher 4.7 times than previously reported (39.6 mg/L).

• Journal of Applied Biological Chemistry
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• v.64 no.3
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• pp.309-316
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• 2021

Kaempferol 3-O-galactoside (Trifolin), a member of the flavonol group, has been reported to have anticancer effects against promyelocytic leukemia, histocytic lymphoma, skin melanoma and lung cancer. Trifolin has been extracted and used from several plants, but the extraction process is complicated and the final yield is low. Biotransformation is an alternative tool to produce high value-added chemicals from inexpensive compounds. To synthesis trifolin from naringenin, three genes (PeFLS and OsUGE-PhUGT) were introduced into Escherichia coli, respectively. In order to synthesis trifolin from naringenin, a co-culture fermentation system was established by optimizing the cell concentration, biotransformation temperature and medium, isopropyl-β-D-thiogalactoside (IPTG) concentration, substrate supply concentration, and recombinant protein induction time. The established optimal conditions for trifolin production were a 3:1 ratio of BL-UGTE to BL-FLS, induction of recombinant protein at 25 ℃ for 4 h after addition of 2.0 mM IPTG, biotransformation at 30 ℃, and supply of 300 μM naringenin. Through the optimized co-culture fermentation system, trifolin was biosynthesized up to 67.3 mg/L.

• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.1-6
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• 2019

The flavonoid, isokaempferide, has various biological activities such as hepatoprotective, antimicrobial and antiproliferative effect and is extracted from Amburana cearensis and Cirsium rivulare (Jacq.). Biotransformation is an alternative tool for the synthesis of value-added flavonoids with inexpensive substrates. Here, to synthesize isokaempferide from naringenin, two genes, PFLS and Rice O-mthyltransferae-9 were introduced in Escherichia coli. Although isokaempferide was successfully synthesized, the amount of biosynthesis was no high. In order to increase the yields of isokaempferide, S-adenosylmethionine (SAM) used as a methyl donor was increased by deleting MetJ, which is a transcriptional regulator related to SAM biosynthetic pathway. Next we optimized the cell concentration and substrate feed concentration with the engineered E. coli strain. Through these strategies, the biosynthesis of isokaempferide was increased up to 87 mg/L.