scholarly journals Optimization of the laccase detoxification step in hybrid hydrolysis and fermentation processes from wheat straw by K. marxianus CECT 10875

Bioethanol ◽  
2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Alfredo Oliva-Taravilla ◽  
Elia Tomás-Pejó ◽  
Marie Demuez ◽  
Cristina González-Fernández ◽  
Mercedes Ballesteros
Keyword(s):  
Enzymatic Hydrolysis ◽  
Ethanol Production ◽  
Wheat Straw ◽  
Positive Impact ◽  
Inoculum Size ◽  
Volumetric Productivity ◽  
Total Phenols ◽  
Fermentation Processes ◽  
Negative Effect

AbstractThe addition of laccase enzymes reduces the amount of phenols present in lignocellulosic pretreated materials and increases their fermentability. However, laccase addition in combination with cellulases reduces hydrolysis yields. In this work, hybrid hydrolysis and fermentation (HHF) configuration allowed overcoming the negative effect of laccase treatment on enzymatic hydrolysis. Furthermore, the effects of different laccase dosages, length of detoxification time and inoculum size on ethanol production were evaluated. In the evaluated configurations, the different laccase dosages did not show any significant effect on enzymatic hydrolysis. The lowest laccase dosage (0.5 IU/g DW) removed ~70% of total phenols which was enough to reach the highest ethanol production yields (~10 g/L) using K. marxianus CECT 10875. Shorter detoxification times and larger inoculum sizes had a positive impact on both ethanol production and volumetric productivity. These optimal detoxification conditions enable the fermentation of inhibitory slurries by reducing the overall time and cost of the process.

Comparison of Low-Temperature Alkali/Urea Pretreatments for Ethanol Production from Wheat Straw

2021 ◽  
Vol 15 (3) ◽  
pp. 399-407
Author(s):  
Zahoor ◽  
Wen Wang ◽  
Xuesong Tan ◽  
Qiang Yu ◽  
Yongming Sun ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Enzymatic Hydrolysis ◽  
Low Temperature ◽  
Ethanol Production ◽  
Wheat Straw ◽  
Response Surface ◽  
Cellulosic Ethanol ◽  
Enzymatic Saccharification ◽  
Hydrolysis Of ◽  
Bioethanol Yield

NaOH/urea (NU) pretreatment at lower than 0 °C has been frequently applied for improving bio-conversion of lignocellulose, but the wastewater generated from the pretreatment process is hard to dispose. KOH/urea (KU) pretreatment for enhancing bioconversion of lignocellulose has recently attracted researchers’ attention due to the recycling of wastewater for facilitating crops’ growth. This study compared the effects of NU and KU pretreatments at cold conditions on the enzymatic hydrolysis and bioethanol yield from wheat straw (WS). By using response surface methodology an optimal pretreatment with an equal ratio of alkali/urea (4% w/v) at −20 °C for 3 h was established. The enzymatic hydrolysis of KU-treated WS was 81.17%, which was similar to that of NU-treated WS (83.72%) under the same condition. It means that KU pretreatment has equal ability to NU pretreatment to improve enzymatic saccharification of lignocellulose. KU pretreatment has the promising potential to replace NU pretreatment for facilitating bioconversion of lignocellulose in cold conditions due to the clean way to recycle its wastewater as fertilizer for crop growth. Hence, KU pretreatment combined with enzymatic hydrolysis and fermentation could be a promising green way to cellulosic ethanol production with zero waste emission.

scholarly journals Comprehensive understanding of the effects of metallic cations on enzymatic hydrolysis of humic acid-pretreated waste wheat straw

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Wei Tang ◽  
Xinxing Wu ◽  
Caoxing Huang ◽  
Zhe Ling ◽  
Chenhuan Lai ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Wheat Straw ◽  
Cellulase Activity ◽  
Unit Operation ◽  
Comprehensive Understanding ◽  
Negative Effect ◽  
Metallic Cations ◽  
Hydrolysis Of ◽  
Positive Effect ◽  
Inhibition Ability

Abstract Background Humic acids (HA) have been used in biorefinery process due to its surfactant properties as an aid to the pretreatment of lignocellulose, with results indicating a positive effect on delignification. However, the HA remaining on the surface of the pretreated lignocellulose has also been shown to provide a negative effect on ensuing enzymatic digestibility. Hence, a strategy of complexing metallic cations with HA prior to enzymatic hydrolysis was proposed and demonstrated in this work in an effort to provide a means of HA mitigation that does not involve significant water consumption via extensive washing. Results Results showed that the enzymatic hydrolysis efficiency of waste wheat straw decreased from 81.9% to 66.1% when it was pretreated by 10 g/L HA, attributed to the inhibition ability of the residual HA on enzyme activity of cellulase with a debasement of 36.3%. Interestingly, enzymatic hydrolysis efficiency could be increased from 66.1% to 77.3% when 10 mM Fe3+ was introduced to the system and allowed to associate with HA during saccharification. Conclusions The addition of high-priced metallic cations (Fe3+) has successfully alleviated the effect of HA on cellulase activity. It is our hope in demonstrating the complexation affinity between metallic cations and HA, future researchers and biorefinery developers will evaluate this strategy as a unit operation that could allow economic biorefining of WWS to produce valuable biochemicals, biofuels, and biomaterials.

Pretreatment of wheat straw by supercritical CO2 and its enzymatic hydrolysis for sugar production

2010 ◽  
Vol 107 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Roozbeh Alinia ◽  
Samyar Zabihi ◽  
Feridun Esmaeilzadeh ◽  
Jamshid Fathi Kalajahi
Keyword(s):  
Enzymatic Hydrolysis ◽  
Wheat Straw ◽  
Supercritical Co2 ◽  
Sugar Production

scholarly journals Impact of Economic Freedom on Corruption Revisited in ASEAN Countries: A Bayesian Hierarchical Mixed-Effects Analysis

Economies ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 3
Author(s):  
Nguyen Ngoc Thach ◽  
Bui Hoang Ngoc
Keyword(s):  
Economic Freedom ◽  
Positive Impact ◽  
Mixed Effects ◽  
Random Coefficients ◽  
Bayesian Hierarchical ◽  
Country Level ◽  
Corruption Index ◽  
Negative Effect ◽  
Economic Freedom Index ◽  
Asean Countries

Conceptual and applied studies assessing the linkage between economic freedom and corruption expect that economic freedom boosts economic growth, improves income, and reduces levels of corruption. However, most of them have concentrated on developed and developing groups, while Association of Southeast Asian Nations (ASEAN) countries have drawn much less attention. Empirical findings are most often conflicting. Moreover, previous studies performed rather simple frequentist techniques regressing one or some freedom indices on corruption that do not allow for grasping all the aspects of economic freedom as well as capturing variations across countries. The study aims to investigate the effects of ten components of economic freedom index on the level of corruption in ten ASEAN countries from 1999 to 2018. By applying a Bayesian hierarchical mixed-effects regression via a Monte Carlo technique combined with the Gibbs sampler, the obtained results suggest several findings as follows: (i) In view of probability, the predictors property rights, government integrity, tax burden, business freedom, labor freedom, and investment freedom have a strongly positive impact on the response perceived corruption index; (ii) Government spending, trade freedom, and financial freedom exert a strongly negative effect, while the influence of monetary freedom is ambiguous; (iii) There is an existence of not only random intercepts but also random coefficients at the country level impacting the model outcome. The empirical outcome could be of major importance for more efficient corruption controlling in emerging countries, including ASEAN nations.

Infrastructure and Trade: An Empirical Study Based on China and Selected Asian Economies

SAGE Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 215824402110360
Author(s):  
Imran Ur Rahman ◽  
Mohsin Shafi ◽  
Liu Junrong ◽  
Enitilina Tatiani M.K. Fetuu ◽  
Shah Fahad ◽  
...  
Keyword(s):  
Positive Impact ◽  
Ordinary Least Squares ◽  
Trade Flows ◽  
Transport Infrastructure ◽  
Sea Transport ◽  
Asian Economies ◽  
Negative Effect ◽  
Ict Infrastructure ◽  
High Standards ◽  
Merchandise Trade

We empirically determine the role of different forms of infrastructure on a country’s trade. We use an augmented gravity model that incorporates infrastructure in the estimation of merchandise trade flows. We take panel data, including China and 21 selected Asian economies, from 1999 to 2018. We find that the panel ordinary least squares (OLS) and poisson pseudo maximum likelihood (PPML) model estimations prove to be significant. Proxies for Transport Infrastructure including roads, railways, and sea transport, and Proxies for information and communication technology (ICT) infrastructure consisting of mobile, electricity, and internet connections show a strong and positive impact on trade while air transport and landline phone connection have an unexpected negative effect on trade. The positive estimates for quality of infrastructure signify that high standards of Transport and ICT infrastructures lead to increased trade flows of the exporting and importing countries. Results also show that cultural similarity leads to increased trade flows between China and its trading partners in Asia.

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