scholarly journals Stepwise metabolic engineering of Candida tropicalis for efficient xylitol production from xylose mother liquor

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Lihua Zhang ◽  
Zhen Chen ◽  
Junhua Wang ◽  
Wei Shen ◽  
Qi Li ◽  
...  
Keyword(s):  
Metabolic Engineering ◽  
Candida Tropicalis ◽  
Mother Liquor ◽  
Glucose Dehydrogenase ◽  
Organic Pollutant ◽  
Value Added ◽  
Xylitol Production ◽  
Regeneration System ◽  
Nadph Regeneration ◽  
Xylose Mother Liquor

Abstract Background Commercial xylose purification produces xylose mother liquor (XML) as a major byproduct, which has become an inexpensive and abundant carbon source. A portion of this XML has been used to produce low-value-added products such as caramel but the remainder often ends up as an organic pollutant. This has become an issue of industrial concern. In this study, a uracil-deficient Candida tropicalis strain was engineered to efficiently convert XML to the commercially useful product xylitol. Results The xylitol dehydrogenase gene was deleted to block the conversion of xylitol to xylulose. Then, an NADPH regeneration system was added through heterologous expression of the Yarrowia lipolytica genes encoding 6-phosphate-gluconic acid dehydrogenase and 6-phosphate-glucose dehydrogenase. After process optimization, the engineered strain, C. tropicalis XZX-B4ZG, produced 97.10 g L− 1 xylitol in 120 h from 300 g L− 1 XML in a 5-L fermenter. The xylitol production rate was 0.82 g L− 1 h− 1 and the conversion rate was 92.40 %. Conclusions In conclusion, this study performed a combination of metabolic engineering and process optimizing in C. tropicalis to enhance xylitol production from XML. The use of C. tropicalis XZX-B4ZG, therefore, provided a convenient method to transform the industrial by-product XML into the useful material xylitol.

scholarly journals Metabolic Engineering of Bacillus subtilis for 2.3-BDO production by introducing an exogenous NADPH/NADP+ regeneration system

2019 ◽  
Author(s):  
Huiling Liu ◽  
Shuangying Liu ◽  
Fengyu Xie ◽  
Xian Zhang ◽  
Meijuan Xu ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Metabolic Engineering ◽  
Carbon Flux ◽  
Glucose Dehydrogenase ◽  
Transcriptional Regulator ◽  
Pentose Phosphate ◽  
Regeneration System ◽  
Nadph Regeneration ◽  
By Products ◽  
Regeneration Systems

Abstract Background: Generally, glucose is transformed into pyruvate from glycolysis before the target products acetoin and 2,3-butanediol (2,3-BDO) are formed. Pentose Phosphate Pathway (PPP) is an inefficient synthetic pathway for pyruvate production from glucose in Bacillus subtilis. Previously, it was found that engineered PPP in B. subtilis unbalanced NADH and NADPH regeneration systems and affected acetoin and 2,3 -BDO production.Results: In this study, metabolic engineering strategies were proposed to redistribute carbon flux to 2,3-BDO via reconstructing intracellular cofactors regeneration systems. Firstly, extra copies of glucose dehydrogenase (GDH)and an exogenous NADPH-dependent 2,3-BDO dehydrogenase (TDH) were introduced into the GRAS strain B. subtilis 168 to introduce an exogenous NADPH/NADP + regeneration system and broaden 2,3-BDO production pathway. It was found that overexpressing the NADPH/NADP + regeneration system effectively improved 2,3-BDO production and inhibited NADH-dependent by-products accumulation. Subsequently, the disruption of lactate dehydrogenase (encoded by ldh ) by insertion of the transcriptional regulator ALsR, essential for the expression of alsSD (encoding two key enzymes for the conversion of pyruvate to acetoin) in B. subtilis, resulted in the recombinant strain in which alsSD was overexpressed and the pathway to lactate was blocked simultaneously. On fermentation by the result engineered strain, the highest 2,3-BDO concentration increased by18.43%, while the titers of main byproducts acetoin and lactate decreased by 22.03% and 64%, respectively.Conclusion: In this study, it shows that engineering PPP and reconstructing intracellular cofactors regeneration system could be an alternative strategy in the metabolic engineering of 2,3-BDO production in B. subtilis .

Increased xylitol production rate during long-term cell recycle fermentation of Candida tropicalis

2004 ◽  
Vol 26 (8) ◽  
pp. 623-627 ◽  
Author(s):  
Teak-Bum Kim ◽  
Yong-Joo Lee ◽  
Pil Kim ◽  
Chang Sup Kim ◽  
Deok-Kun Oh
Keyword(s):  
Production Rate ◽  
Candida Tropicalis ◽  
Xylitol Production ◽  
Cell Recycle

scholarly journals Tuning a bi-enzymatic cascade reaction in Escherichia coli to facilitate NADPH regeneration for ε-caprolactone production

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jinghui Xiong ◽  
Hefeng Chen ◽  
Ran Liu ◽  
Hao Yu ◽  
Min Zhuo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Sites ◽  
Regeneration System ◽  
Nadph Regeneration ◽  
Whole Cell ◽  
Cyclohexanone Monooxygenase ◽  
Ribosome Binding ◽  
Ribosome Binding Sites ◽  
Whole Cell Biocatalyst ◽  
Substrate Tolerance

Abstractε-Caprolactone is a monomer of poly(ε-caprolactone) which has been widely used in tissue engineering due to its biodegradability and biocompatibility. To meet the massive demand for this monomer, an efficient whole-cell biocatalytic approach was constructed to boost the ε-caprolactone production using cyclohexanol as substrate. Combining an alcohol dehydrogenase (ADH) with a cyclohexanone monooxygenase (CHMO) in Escherichia coli, a self-sufficient NADPH-cofactor regeneration system was obtained. Furthermore, some improved variants with the better substrate tolerance and higher catalytic ability to ε-caprolactone production were designed by regulating the ribosome binding sites. The best mutant strain exhibited an ε-caprolactone yield of 0.80 mol/mol using 60 mM cyclohexanol as substrate, while the starting strain only got a conversion of 0.38 mol/mol when 20 mM cyclohexanol was supplemented. The engineered whole-cell biocatalyst was used in four sequential batches to achieve a production of 126 mM ε-caprolactone with a high molar yield of 0.78 mol/mol.

scholarly journals Cascading Old Yellow Enzyme, Alcohol Dehydrogenase and Glucose Dehydrogenase for Selective Reduction of (E/Z)-Citral to (S)-Citronellol

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 931
Author(s):  
Yunpeng Jia ◽  
Qizhou Wang ◽  
Jingjing Qiao ◽  
Binbin Feng ◽  
Xueting Zhou ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Glucose Dehydrogenase ◽  
Selective Reduction ◽  
Coli Strain ◽  
Severe Reaction ◽  
High Catalytic Activity ◽  
Old Yellow Enzyme ◽  
One Pot ◽  
Nadph Regeneration ◽  
By Products

Citronellol is a kind of unsaturated alcohol with rose-like smell and its (S)-enantiomer serves as an important intermediate for organic synthesis of (-)-cis-rose oxide. Chemical methods are commonly used for the synthesis of citronellol and its (S)-enantiomer, which suffers from severe reaction conditions and poor selectivity. Here, the first one-pot double reduction of (E/Z)-citral to (S)-citronellol was achieved in a multi-enzymatic cascade system: N-ethylmaleimide reductase from Providencia stuartii (NemR-PS) was selected to catalyze the selective reduction of (E/Z)-citral to (S)-citronellal, alcohol dehydrogenase from Yokenella sp. WZY002 (YsADH) performed the further reduction of (S)-citronellal to (S)-citronellol, meanwhile a variant of glucose dehydrogenase from Bacillus megaterium (BmGDHM6), together with glucose, drove efficient NADPH regeneration. The Escherichia coli strain co-expressing NemR-PS, YsADH, and BmGDHM6 was successfully constructed and used as the whole-cell catalyst. Various factors were investigated for achieving high conversion and reducing the accumulation of the intermediate (S)-citronellal and by-products. 0.4 mM NADP+ was essential for maintaining high catalytic activity, while the feeding of the cells expressing BmGDHM6 effectively eliminated the intermediate and by-products and shortened the reaction time. Under optimized conditions, the bio-transformation of 400 mM citral caused nearly complete conversion (>99.5%) to enantio-pure (S)-citronellol within 36 h, demonstrating promise for industrial application.

Biotin and Zn2+ Increase Xylitol Production by Candida tropicalis

2021 ◽  
Author(s):  
Gurusamy Muneeswaran ◽  
Sanjay K. S. Patel ◽  
Sanath Kondaveeti ◽  
Ramasamy Shanmugam ◽  
Krishnasamy Gopinath ◽  
...  
Keyword(s):  
Candida Tropicalis ◽  
Xylitol Production

scholarly journals Construction and characterization of a novel glucose dehydrogenase-leucine dehydrogenase fusion enzyme for the biosynthesis of l-tert-leucine

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Langxing Liao ◽  
Yonghui Zhang ◽  
Yali Wang ◽  
Yousi Fu ◽  
Aihui Zhang ◽  
...  
Keyword(s):  
Glucose Dehydrogenase ◽  
Catalytic Efficiency ◽  
Space Time ◽  
Cofactor Regeneration ◽  
Enzyme Complex ◽  
Regeneration System ◽  
Regeneration Rate ◽  
Leucine Dehydrogenase ◽  
Fusion Enzyme ◽  
Space Time Yield

Abstract Background Biosynthesis of l-tert-leucine (l-tle), a significant pharmaceutical intermediate, by a cofactor regeneration system friendly and efficiently is a worthful goal all the time. The cofactor regeneration system of leucine dehydrogenase (LeuDH) and glucose dehydrogenase (GDH) has showed great coupling catalytic efficiency in the synthesis of l-tle, however the multi-enzyme complex of GDH and LeuDH has never been constructed successfully. Results In this work, a novel fusion enzyme (GDH–R3–LeuDH) for the efficient biosynthesis of l-tle was constructed by the fusion of LeuDH and GDH mediated with a rigid peptide linker. Compared with the free enzymes, both the environmental tolerance and thermal stability of GDH–R3–LeuDH had a great improved since the fusion structure. The fusion structure also accelerated the cofactor regeneration rate and maintained the enzyme activity, so the productivity and yield of l-tle by GDH–R3–LeuDH was all enhanced by twofold. Finally, the space–time yield of l-tle catalyzing by GDH–R3–LeuDH whole cells could achieve 2136 g/L/day in a 200 mL scale system under the optimal catalysis conditions (pH 9.0, 30 °C, 0.4 mM of NAD+ and 500 mM of a substrate including trimethylpyruvic acid and glucose). Conclusions It is the first report about the fusion of GDH and LeuDH as the multi-enzyme complex to synthesize l-tle and reach the highest space–time yield up to now. These results demonstrated the great potential of the GDH–R3–LeuDH fusion enzyme for the efficient biosynthesis of l-tle.

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