scholarly journals Effect of Evolutionary Adaptation on Metabolic Enzyme Activities of Thermotolerant Strain Kluyveromyces Marxianus NIRE-K1 and NIRE-K3 for Bioethanol Production

2021 ◽  
Author(s):  
Nilesh Kumar Sharma ◽  
Shuvashish Behera ◽  
Richa Arora ◽  
Sachin Kumar
Keyword(s):  
Ethanol Production ◽  
Enzyme Activities ◽  
Kluyveromyces Marxianus ◽  
Reductase Activity ◽  
Xylose Reductase ◽  
Metabolic Enzyme ◽  
Xylose Utilization ◽  
Ms Medium ◽  
Evolutionary Adaptation ◽  
Xylose Uptake

Abstract Evolutionary adaptation provides stability to the strains in the challenging environment. As extension of earlier study, the evolved strains Kluyveromyces marxianus NIRE-K1.1 and K. marxianus NIRE-K3.1 were subjected for secondary adaptation on minimal salt (MS) medium with the aim to enhance xylose utilization for ethanol production together with salt tolerance. Both the strains were adapted till saturated improvement in xylose uptake i.e., 54 generations on MS medium containing xylose. Xylose utilization increased from 14.21 to 45.80% and 10.55 to 45.31%, in evolved strains KmNIRE-K1.2 and KmNIRE-K3.2, respectively. Specific xylose reductase activity has also increased 2.04 and 3.36-folds in KmNIRE-K1.2 and KmNIRE-K3.2, respectively. Xylitol dehydrogenase activity was also increased by 2.82 and 1.35-folds in KmNIRE-K1.2 and KmNIRE-K3.2, respectively. Decrease in redox imbalance was observed in evolved strains, and hence there was a reduction in xylitol production during growth and fermentation. Xylose uptake rate increased by 2.53 and 1.5-folds in KmNIRE-K1.2 and KmNIRE-K3.2, respectively with 2.20 and 6.46-folds higher ethanol concentration, and 2.25 and 5.86-folds higher volumetric productivity, respectively. This study has demonstrated the role of evolutionary adaptation for developing robust yeast strains. KmNIRE-K1.2 and KmNIRE-K3.2 have shown enhanced ethanol production, enzyme activities and less by-product formation like xylitol during xylose metabolism.

scholarly journals Simultaneous saccharification and co-fermentation with a thermotolerant Saccharomyces cerevisiae to produce ethanol from sugarcane bagasse under high temperature conditions

BioResources ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. 1358-1372
Author(s):  
Wei-Lin Tu ◽  
Tien-Yang Ma ◽  
Chung-Mao Ou ◽  
Gia-Luen Guo ◽  
Yu Chao
Keyword(s):  
Saccharomyces Cerevisiae ◽  
High Temperature ◽  
Ethanol Production ◽  
Sugarcane Bagasse ◽  
Ethanol Yield ◽  
Xylose Utilization ◽  
Inhibitor Tolerance ◽  
Temperature Conditions ◽  
Xylose Uptake ◽  
Simultaneous Saccharification

Lignocellulosic ethanol production at high temperature offers advantages such as the decrease of contamination risk and cooling cost. Recombinant xylose-fermenting Saccharomyces cerevisiae has been considered a promising strain for ethanol production from lignocellulose for its high inhibitor tolerance and superior capability to ferment glucose and xylose into ethanol. To improve the ethanolic fermentation by xylose at high temperature, the strain YY5A was subjected to the ethyl methanesulfonate (EMS) mutagenesis. A mutant strain T5 was selected from the EMS-treated cultures to produce ethanol. However, the xylose uptake by T5 was severely inhibited by the high ethanol concentration during the co-fermentation in defined YPDX medium at 40 °C. In this study, the simultaneous saccharification and co-fermentation (SSCF) and the separate hydrolysis and co-fermentation (SHCF) processes of sugarcane bagasse were assessed to solve this problem. The xylose utilization by T5 was remarkably improved using the SSCF process compared to the SHCF process. For the SHCF and SSCF processes, 48% and 99% of the xylose in the hydrolysate was consumed at 40 °C, respectively. The ethanol yield was enhanced by the SSCF process. The ethanol production can reach to 36.0 g/L using this process under high-temperature conditions.

Simultaneous optimization of activity and stability of xylose reductase from D. nepalensis NCYC 3413 using statistical experimental design

2020 ◽  
Vol 27 ◽  
Author(s):  
Shwethashree Malla ◽  
Sathyanarayana N. Gummadi
Keyword(s):  
Half Life ◽  
Specific Activity ◽  
Enzyme Stability ◽  
Reductase Activity ◽  
Xylose Reductase ◽  
Life Time ◽  
Economic Feasibility ◽  
Simultaneous Optimization ◽  
Physical Parameters ◽  
Statistical Experimental Design

Background: Physical parameters like pH and temperature play a major role in the design of an industrial enzymatic process. Enzyme stability and activity are greatly influenced by these parameters; hence optimization and control of these parameters becomes a key point in determining the economic feasibility of the process. Objective: This study was taken up with the objective to optimize physical parameters for maximum stability and activity of xylose reductase from D. nepalensis NCYC 3413 through separate and simultaneous optimization studies and comparison thereof. Method: Effects of pH and temperature on the activity and stability of xylose reductase from Debaryomyces nepalensis NCYC 3413 were investigated by enzyme assays and independent variables were optimised using surface response methodology. Enzyme activity and stability were optimised separately and concurrently to decipher the appropriate conditions. Results: Optimized conditions of pH and temperature for xylose reductase activity were determined to be 7.1 and 27 ℃ respectively, with predicted responses of specific activity (72.3 U/mg) and half-life time (566 min). The experimental values (specific activity 50.2 U/mg, half-life time 818 min) were on par with predicted values indicating the significance of the model. Conclusion: Simultaneous optimization of xylose reductase activity and stability using statistical methods is effective as compared to optimisation of the parameters separately.

scholarly journals Hemicellulosic Bioethanol Production from Fast-Growing Paulownia Biomass

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 173
Author(s):  
Elena Domínguez ◽  
Pablo G. del Río ◽  
Aloia Romaní ◽  
Gil Garrote ◽  
Lucília Domingues
Keyword(s):  
Ethanol Production ◽  
Ethanol Concentration ◽  
Ethanol Yield ◽  
Xylose Reductase ◽  
Energy Crop ◽  
Scheffersomyces Stipitis ◽  
Fractionation Process ◽  
Renewable Source ◽  
Fast Growing ◽  
Engineered Strain

In order to exploit a fast-growing Paulownia hardwood as an energy crop, a xylose-enriched hydrolysate was obtained in this work to increase the ethanol concentration using the hemicellulosic fraction, besides the already widely studied cellulosic fraction. For that, Paulownia elongata x fortunei was submitted to autohydrolysis treatment (210 °C or S0 of 4.08) for the xylan solubilization, mainly as xylooligosaccharides. Afterwards, sequential stages of acid hydrolysis, concentration, and detoxification were evaluated to obtain fermentable sugars. Thus, detoxified and non-detoxified hydrolysates (diluted or not) were fermented for ethanol production using a natural xylose-consuming yeast, Scheffersomyces stipitis CECT 1922, and an industrial Saccharomyces cerevisiae MEC1133 strain, metabolic engineered strain with the xylose reductase/xylitol dehydrogenase pathway. Results from fermentation assays showed that the engineered S. cerevisiae strain produced up to 14.2 g/L of ethanol (corresponding to 0.33 g/g of ethanol yield) using the non-detoxified hydrolysate. Nevertheless, the yeast S. stipitis reached similar values of ethanol, but only in the detoxified hydrolysate. Hence, the fermentation data prove the suitability and robustness of the engineered strain to ferment non-detoxified liquor, and the appropriateness of detoxification of liquor for the use of less robust yeast. In addition, the success of hemicellulose-to-ethanol production obtained in this work shows the Paulownia biomass as a suitable renewable source for ethanol production following a suitable fractionation process within a biorefinery approach.

Glutathione metabolic enzyme activities in diabetic platelets as a function of glycemic control

1992 ◽  
Vol 67 (4) ◽  
pp. 385-397 ◽  
Author(s):  
Arumugam Muruganandam ◽  
Christine Drouillard ◽  
Roger J. Thibert ◽  
Raphael M-C.Cheung ◽  
Thomas F.Draisey ◽  
...  
Keyword(s):  
Glycemic Control ◽  
Enzyme Activities ◽  
Metabolic Enzyme
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