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1,746 results on '"Zheng, Yu-Guo"'

211. Improving the catalytic activity of β-glucosidase from Coniophora puteana via semi-rational design for efficient biomass cellulose degradation

Author

Zhou, Hai-Yan, primary, Chen, Qi, additional, Zhang, Yi-Feng, additional, Chen, Dou-Dou, additional, Yi, Xiao-Nan, additional, Chen, De-Shui, additional, Cheng, Xin-Ping, additional, Li, Mian, additional, Wang, Hong-Yan, additional, Chen, Kai-Qian, additional, Liu, Zhi-Qiang, additional, and Zheng, Yu-Guo, additional

Published
2022
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235. Investigation of the enhancement for Echinocandin B fermentation with methyl oleate from transcription level.

Author

Niu, Kun, Qi, Yu-Xin, Cai, Hong-Wei, Ye, Yi-Xin, Zhou, Hai-Yan, Liu, Xiao-Tian, Liu, Zhi-Qiang, and Zheng, Yu-Guo

Abstract

Echinocandin B (ECB) is the key precursor compound of the antifungal drug Anidulafungin. The effects of the five precursor amino acids on ECB biosynthesis were firstly investigated. It showed that although L-threonine was a main compound of the hexapeptide scaffold of ECB, exogenous addition of L-threonine had no significant effect on the increase of ECB fermentation titer. Meanwhile, the ECB fermentation titer with methyl oleate showed two times higher than that of the other carbon sources. Transcription level analysis of the key genes for ECB biosynthesis indicated that the gene an655543 related to L-threonine biosynthesis showed higher value during the fermentation process, therefore, the exogenous addition of L-threonine had no obvious affection. Furthermore, it indicated that the transcription level of gene ecdA might be the main restriction factor for the ECB biosynthesis. The study provided the research foundation for the modification of the ECB producing strains in the following work. [ABSTRACT FROM AUTHOR]

Published
2023
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237. Coevolving stability and activity of LsCR by a single point mutation and constructing neat substrate bioreaction system.

Author

Liu, Hua‐Tao, Weng, Chun‐Yue, Zhou, Lei, Xu, Hao‐Bo, Liao, Zhen‐Yu, Hong, Han‐Yue, Ye, Yuan‐Fan, Li, Shu‐Fang, Wang, Ya‐Jun, and Zheng, Yu‐Guo

Abstract

Carbonyl reductase (CR)‐catalyzed bioreduction in the organic phase and the neat substrate reaction system is a lasting challenge, placing higher requirements on the performance of enzymes. Protein engineering is an effective method to enhance the properties of enzymes for industrial applications. In the present work, a single point mutation E145A on our previously constructed CR mutant LsCRM3, coevolved thermostability, and activity. Compared with LsCRM3, the catalytic efficiency kcat/KM of LsCRM3‐E145A (LsCRM4) was increased from 6.6 to 21.9 s−1 mM−1. Moreover, E145A prolonged the half‐life t1/2 at 40°C from 4.1 to 117 h, Tm ${T}_{m}$ was increased by 5°C, T5030 ${T}_{50}^{30}$ was increased by 14.6°C, and Topt was increased by 15°C. Only 1 g/L of lyophilized Escherichia coli cells expressing LsCRM4 completely reduced up to 600 g/L 2‐chloro‐1‐(3,4‐difluorophenyl)ethanone (CFPO) within 13 h at 45°C, yielding the corresponding (1S)‐2‐chloro‐1‐(3,4‐difluorophenyl)ethanol ((S)‐CFPL) in 99.5% eeP, with a space‐time yield of 1.0 kg/L d, the substrate to catalyst ratios (S/C) of 600 g/g. Compared with LsCRM3, the substrate loading was increased by 50%, with the S/C increased by 14 times. Compared with LsCRWT, the substrate loading was increased by 6.5 times. In contrast, LsCRM4 completely converted 600 g/L CFPO within 12 h in the neat substrate bioreaction system. [ABSTRACT FROM AUTHOR]

Published
2023
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244. Combinatorial Metabolic Engineering of Escherichia colifor Enhanced L-Cysteine Production: Insights into Crucial Regulatory Modes and Optimization of Carbon-Sulfur Metabolism and Cofactor Availability

Author

Yang, Hui, Zhang, Bo, Wu, Zi-Dan, Chen, Li-Feng, Pan, Jia-Yuan, Xiu, Xiao-Ling, Cai, Xue, Liu, Zhi-Qiang, and Zheng, Yu-Guo

Abstract

Microbial production of valuable compounds can be enhanced by various metabolic strategies. This study proposed combinatorial metabolic engineering to develop an effective Escherichia colicell factory dedicated to L-cysteine production. First, the crucial regulatory modes that control L-cysteine levels were investigated to guide metabolic modifications. A two-stage fermentation was achieved by employing multi-copy gene expression, improving the balance between production and growth. Subsequently, carbon flux distribution was further optimized by modifying the C1 unit metabolism and the glycolytic pathway. The modifications of sulfur assimilation demonstrated superior performance of thiosulfate utilization pathways in enhancing L-cysteine titer. Furthermore, the studies focusing on cofactor availability and preference emphasized the vital role of synergistic enhancement of sulfur-carbon metabolism in L-cysteine overproduction. In a 5 L bioreactor, the strain BW15-3/pED accumulated 12.6 g/L of L-cysteine. This work presented an effective metabolic engineering strategy for the development of L-cysteine-producing strains.

Published
2023
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