Dry biodetoxification of acid pretreated wheat straw for cellulosic ethanol fermentation

Abstract

Background

The efficient removal of toxic inhibitors from pretreated lignocellulose biomass is crucially important for consequent cellulosic ethanol fermentation. A. resinae ZN1 biodetoxifies all toxic inhibitors at the neutral pH of 4–6, and the neutralization of acid catalyst in the pretreated lignocellulose is required. However, aqueous alkaline solutions such as sodium hydroxide solution and calcium hydroxide slurry are used which generate several difficulties.

Results

In this study, a dry biodetoxification method was investigated using dry calcium carbonate (CaCO₃) powder as an acid-neutralizing reagent to avoid the use of an aqueous alkaline solution. Dry biodetoxification provides a mild and stable pH without the generation of phenolic compounds. The acid pretreated and dry biodetoxified wheat straw was used as the feedstock of ethanol fermentation and the same performance with the wet biodetoxification using aqueous Ca(OH)₂ slurry. The 72 g/L or 9.1% (v/v) of ethanol produced from wheat straw was very close to that of ethanol from corn starch.

Conclusions

Dry biodetoxification provided a practical method to simplify the process of conventional wet biodetoxification to reduce the time, cost and labor.

Keywords

Biodetoxification / Acid pretreatment / Ethanol / Calcium carbonate (CaCO₃) powder / Lignocellulose

References

[1] Dong H, Bao J. Biofuel via biodetoxification. Nat Chem Biol, 2010, 6: 316-318.

[2] Gu HQ, Zhang J, Bao J. High tolerance and physiological mechanism of Zymomonas mobilis to phenolic inhibitors in ethanol fermentation of corncob residue. Biotechnol Bioeng, 2015, 112: 1770-1782.

[3] He YQ, Zhang LP, Zhang J, Bao J. Helically agitated mixing in dry dilute acid pretreatment enhances the bioconversion of corn stover into ethanol. Biotechnol Biofuels, 2014, 7: 1.

[4] Jing X, Zhang X, Bao J. Inhibition performance of lignocellulose degradation products on industrial cellulase enzymes during cellulose hydrolysis. Appl Biochem Biotechnol, 2009, 159: 696-707.

[5] Klinke HB, Thomsen AB, Ahring BK. Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass. Appl Microbiol Biotechnol, 2014, 66: 10-26.

[6] Li H, Wu M, Xu L, Jin H, Guo T, Bao X. Evaluation of industrial Saccharomyces cerevisiae strains as the chassis cell for second-generation bioethanol production. Microb Biotechnol, 2015, 82: 6.

[7] Liu G, Bao J. Maximizing cellulosic ethanol potentials by minimizing wastewater generation and energy consumption: competing with corn ethanol. Bioresour Technol, 2017, 245: 18-26.

[8] Liu G, Zhang Q, Li H, Qureshi AS, Zhang J, Bao X, Bao J. Dry biorefining maximizes the potentials of simultaneous saccharification and co-fermentation for cellulosic ethanol production. Biotechnol Bioeng, 2018, 115: 60-69.

[9] Palmqvist E, Hahn-Hagerdal B. Fermentation of lignocellulosic hydrolysates. I: inhibition and detoxification. Bioresour Technol, 2000, 74: 17-24.

[10] Qiu Z, Gao Q, Bao J. Constructing xylose-assimilating pathways in Pediococcus acidilactici for high titer D-lactic acid fermentation from corn stover feedstock. Bioresour Technol, 2017, 245: 1369-1376.

[11] Qiu Z, Gao Q, Bao J. Engineering Pediococcus acidilactici with xylose assimilation pathway for high titer cellulosic L-lactic acid fermentation. Bioresour Technol, 2018, 249: 9-15.

[12] Sluiter A, Hames B, Ruiz R, Scarlata C, Sluiter J, Templeton D. Determination of sugars, byproducts and degradation products in liquid fraction process samples. NREL/TP-510-42623, 2008, Golden: National Renewable Energy Laboratory.

[13] Sluiter A, Hames B, Ruiz R, Scarlata C, Sluiter J, Templeton D, Crocker D. Determination of structural carbohydrates and lignin in biomass. NREL/TP-510-42618, 2012, Golden: National Renewable Energy Laboratory.

[14] Wen J, Xiao Y, Liu T, Gao Q, Bao J. Rich biotin content in lignocellulose biomass plays the key role in determining cellulosic glutamic acid accumulation by Corynebacterium glutamicum. Biotechnol Biofuels, 2018, 11: 132.

[15] Zhang J, Zhu Z, Wang X, Wang N, Wang W, Bao J. Biodetoxification of toxins generated from lignocellulose pretreatment using a newly isolated fungus, Amorphothec resinae ZN1 and the consequent ethanol fermentation. Biotechnol Biofuels, 2010, 3: 26.

[16] Zhang J, Wang X, Chu D, He Y, Bao J. Dry pretreatment of lignocellulose with extremely low steam and water usage for bioethanol production. Bioresour Technol, 2011, 102: 4480-4488.

[17] Zhang H, Zhang J, Bao J. High titer gluconic acid fermentation by Aspergillus niger from dry dilute acid pretreated corn stover without detoxification. Bioresour Technol, 2016, 203: 211-219.

[18] Zhou PP, Meng J, Bao J. Fermentative production of high titer citric acid from corn stover feedstock after dry dilute acid pretreatment and biodetoxification. Bioresour Technol, 2017, 224: 563-572.

Funding

National Natural Science Foundation of China(31961133006)