scholarly journals Xylitol production from waste xylose mother liquor containing miscellaneous sugars and inhibitors: one-pot biotransformation by Candida tropicalis and recombinant Bacillus subtilis

2016 ◽  
Vol 15 (1) ◽  
Author(s):  
Hengwei Wang ◽  
Lijuan Li ◽  
Lebin Zhang ◽  
Jin An ◽  
Hairong Cheng ◽  
...  
2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Lihua Zhang ◽  
Zhen Chen ◽  
Junhua Wang ◽  
Wei Shen ◽  
Qi Li ◽  
...  

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.


2019 ◽  
Vol 32 ◽  
pp. 1-6
Author(s):  
Raed S. Khudhair ◽  
Elham I. Tami

Xylan produced various agricultural residues including wheat (Furat, Abugraib and Abaa), Papyrus and Sunflower stalks in different ways, including the use of diluted acid, dilute base and self-degradation. The results showed that the acidic method in the production of xylan from various agricultural residues compared with other methods was superior, the highest quantity of xylan 187.6 µg.ml-1 was obtained from the agricultural waste of Papyrus, while it was 157.6, 157.6, 161.6 and 161.3 µg.ml-1 of wheat category of furat, wheat Abu Ghraib, wheat Abaa and sunflower stalks respectively, based on the results obtained, the xylan produced by the acidic method of the different agricultural residues was selected to determine the optimal carboon source for production of xylanase using bacteria Bacillus subtilis strain RS1 locally isolated. After the production of xylitol, the descriptive diagnosis was performed using an HPLC device, depending on the time of the 38.4 minute time lapse reaction of the standard Xylitol and compared with the time of the production of Candida tropicalis, the amount of the processed xylitol was 8.3 µg.ml-1, the calculated xylitol was compared standard xylitol


2004 ◽  
Vol 26 (8) ◽  
pp. 623-627 ◽  
Author(s):  
Teak-Bum Kim ◽  
Yong-Joo Lee ◽  
Pil Kim ◽  
Chang Sup Kim ◽  
Deok-Kun Oh

Author(s):  
Gurusamy Muneeswaran ◽  
Sanjay K. S. Patel ◽  
Sanath Kondaveeti ◽  
Ramasamy Shanmugam ◽  
Krishnasamy Gopinath ◽  
...  

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