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Corynebacterium glutamicum SNK 118 was metabolically engineered with improved L-arginine titer. Considering the crucial role of NADPH level in L-arginine production, pntAB (membrane-bound transhydrogenase) and ppnK (NAD+ kinase) were co-expressed to increase the intracellular NADPH pool. Expression of pntAB exhibited significant effects on NADPH supply and L-arginine synthesis. Furthermore, argR and farR, encoding arginine repressor ArgR and transcriptional regulator FarR, respectively, were removed from the genome of C. glutamicum. The competitive branch pathway gene ldh was also deleted. Eventually, an engineered C. glutamicum JML07 was obtained for L-arginine production. Fed-batch fermentation in 5-L bioreactor employing strain JML07 allowed production of 67.01 g L−1L-arginine with productivity of 0.89 g L−1 h−1 and yield of 0.35 g g−1 glucose. This study provides a productive L-arginine fermentation strain and an effective cofactor manipulating strategy for promoting the biosynthesis of NADPH-dependent metabolites. [ABSTRACT FROM AUTHOR]

Genistein has been regarded as one important soy isoflavone with multiple health benefits, whereas its applications are limited by the low hydrophilicity. To improve the water solubility, codon optimized cyclodextrin glycosyltransferase from Paenibacillus macerans was employed for genistein transglycosylation in this study. At least four transglycosylation products were produced and identified by HPLC and LC-MS: genistein monoglucoside, diglucoside, triglucoside, and tetraglucoside derivatives. Obviously, the yields of genistein monoglucoside and genistein diglucoside exhibited great superiority compared with other two products. To maximize the yield of genistein diglucoside, various reaction conditions such as genistein dissolvents, glycosyl donors, substrates concentrations and ratios, enzyme concentrations, reaction pH, temperature, and time were optimized. Finally, the yield of genistein diglucoside was enhanced by 1.5-fold under the optimum reaction system. Our study demonstrates that the production of genistein diglucoside could be specifically enhanced, which is one important genistein derivative with better water solubility and stability. [ABSTRACT FROM AUTHOR]