Resource recovery of lignocellulosic biomass waste into lactic acid - Trends to sustain cleaner production

2022 ◽  
Vol 301 ◽  
pp. 113925
Author(s):  
Diego A. Esquivel-Hernández ◽  
J. Saúl García-Pérez ◽  
Itzel Y. López-Pacheco ◽  
Hafiz M.N. Iqbal ◽  
Roberto Parra-Saldívar
Keyword(s):  
Lactic Acid ◽  
Lignocellulosic Biomass ◽  
Resource Recovery ◽  
Cleaner Production ◽  
Biomass Waste

scholarly journals Facilely reducing recalcitrance of lignocellulosic biomass by a newly developed ethylamine-based deep eutectic solvent for biobutanol fermentation

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Guochao Xu ◽  
Hao Li ◽  
Wanru Xing ◽  
Lei Gong ◽  
Jinjun Dong ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Lactic Acid ◽  
Lignocellulosic Biomass ◽  
Fossil Fuels ◽  
Deep Eutectic Solvent ◽  
Deep Eutectic Solvents ◽  
Specific Yield ◽  
Green Solvents ◽  
Hydrogen Bond Donor ◽  
Total Sugars

Abstract Background Biobutanol is promising and renewable alternative to traditional fossil fuels and could be produced by Clostridium species from lignocellulosic biomass. However, biomass is recalcitrant to be hydrolyzed into fermentable sugars attributed to the densely packed structure by layers of lignin. Development of pretreatment reagents and processes for increasing surface area, removing hemicellulose and lignin, and enhancing the relative content of cellulose is currently an area of great interest. Deep eutectic solvents (DESs), a new class of green solvents, are effective in the pretreatment of lignocellulosic biomass. However, it remains challenging to achieve high titers of total sugars and usually requires combinatorial pretreatment with other reagents. In this study, we aim to develop novel DESs with high application potential in biomass pretreatment and high biocompatibility for biobutanol fermentation. Results Several DESs with betaine chloride and ethylamine chloride (EaCl) as hydrogen bond acceptors were synthesized. Among them, EaCl:LAC with lactic acid as hydrogen bond donor displayed the best performance in the pretreatment of corncob. Only by single pretreatment with EaCl:LAC, total sugars as high as 53.5 g L−1 could be reached. Consecutive batches for pretreatment of corncob were performed using gradiently decreased cellulase by 5 FPU g−1. At the end of the sixth batch, the concentration and specific yield of total sugars were 58.8 g L−1 and 706 g kg−1 pretreated corncob, saving a total of 50% cellulase. Utilizing hydrolysate as carbon source, butanol titer of 10.4 g L−1 was achieved with butanol yield of 137 g kg−1 pretreated corncob by Clostridium saccharobutylicum DSM13864. Conclusions Ethylamine and lactic acid-based deep eutectic solvent is promising in pretreatment of corncob with high total sugar concentrations and compatible for biobutanol fermentation. This study provides an efficient pretreatment reagent for facilely reducing recalcitrance of lignocellulosic materials and a promising process for biobutanol fermentation from renewable biomass.

scholarly journals Evolutionary Engineering of Lactobacillus Bulgaricus Reduces Enzyme Usage and Enhances Conversion of Lignocellulosics to D-lactic Acid by Simultaneous Saccharification and Fermentation

2020 ◽  
Author(s):  
Vishnu Prasad J. ◽  
Tridweep K. Sahoo ◽  
Naveen S. ◽  
Guhan Jayaraman
Keyword(s):  
Lactic Acid ◽  
Lignocellulosic Biomass ◽  
Simultaneous Saccharification And Fermentation ◽  
Enzyme Hydrolysis ◽  
Lactobacillus Bulgaricus ◽  
Evolutionary Engineering ◽  
Enzyme Loading ◽  
Fermentation Processes ◽  
Platform Chemicals ◽  
Simultaneous Saccharification

Abstract BackgroundSimultaneous saccharification and fermentation (SSF) of pre-treated lignocellulosics to biofuels and other platform chemicals has long been a promising alternative to separate hydrolysis and fermentation processes. However, the disparity between the optimum conditions (temperature, pH) for fermentation and enzyme hydrolysis leads to execution of the SSF process at sub-optimal conditions, which can affect the rate of hydrolysis and cellulose conversion. The fermentation conditions could be synchronized with hydrolysis optima by carrying out the SSF at a higher temperature, but this would require a thermo-tolerant organism. Economically viable production of platform chemicals from lignocellulosic biomass has long been stymied because of the significantly higher cost of hydrolytic enzymes. The major objective of this work is to develop an SSF strategy for D- lactic acid production by a thermo-tolerant organism, in which the enzyme loading could significantly be reduced without compromising on the overall conversion. ResultsA thermo-tolerant strain of Lactobacillus bulgaricuswas developed by adaptive laboratory evolution (ALE) which enabled the SSF to be performed at 45 °C with reduced enzyme usage.Despite the reduction of enzyme loading from 15 FPU/gbiomass to 5 FPU/gbiomass, we could still achieve ~8% higher cellulose to D-LA conversion in batch SSF, in comparison to the conversion by separate enzymatic hydrolysis and fermentation processes at 45 °C and pH 5.5. Extending the batch SSF to an SSF with pulse-feeding of 5% pre-treated biomass and 5 FPU/g-biomass, at12-hour intervals (36th h – 96th h), resulted in a titer of 108 g/L D-LA and 60% conversion of cellulose to D-LA.This is one among the highest reported D-LA titers achieved from lignocellulosic biomass.ConclusionsWe have demonstrated that the SSF strategy, in conjunction with evolutionary engineering, could drastically reduce enzyme requirement and be the way forward for economical production of platform chemicals from lignocellulosics. We have shown that fed-batch SSF processes, designed with multiple pulse-feedings of the pre-treated biomass and enzyme, can be an effective way of enhancing the product concentrations.

scholarly journals Facilely Reducing Recalcitrance of Lignocellulosic Biomass by a Newly Developed Ethylamine Based Deep Eutectic Solvent for Biobutanol Fermentation

2020 ◽  
Author(s):  
Guochao Xu ◽  
Hao Li ◽  
Wanru Xing ◽  
Lei Gong ◽  
Jinjun Dong ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Lactic Acid ◽  
Lignocellulosic Biomass ◽  
Fossil Fuels ◽  
Deep Eutectic Solvent ◽  
Deep Eutectic Solvents ◽  
Specific Yield ◽  
Green Solvents ◽  
Hydrogen Bond Donor ◽  
Total Sugars

Abstract Background: Biobutanol is promising and renewable alternative to traditional fossil fuels and could be produced by Clostridium species from lignocellulosic biomass. However, biomass is recalcitrant to be hydrolyzed into fermentable sugars attributed to the densely packed structure by layers of lignin. Development of pretreatment reagents and processes for increasing surface area, removing hemicellulose and lignin, and enhancing the relative content of cellulose is currently an area of great interest. Deep eutectic solvents (DESs), a new class of green solvents, are effective in the pretreatment of lignocellulosic biomass. However, it remains challenging to achieve high titers of total sugars and usually requires combinatorial pretreatment with other reagents. In this study, we aim to develop novel DESs with high application potential in biomass pretreatment and high biocompatibility for biobutanol fermentation.Results: Several DESs with betaine chloride and ethylamine chloride (EaCl) as hydrogen bond acceptors were synthesized. Among them, EaCl:LAC with lactic acid as hydrogen bond donor displayed the best performance in the pretreatment of corncob. Only by single pretreatment with EaCl:LAC, total sugars of as high as 53.5 g·L–1 could be reached. Consecutive batches for pretreatment of corncob were performed using gradiently decreased cellulase by 5 FPU·g–1. At the end of the sixth batch, the concentration and specific yield of total sugars were 58.8 g·L–1 and 706 g·kg–1 pretreated corncob, saving a total of 50% cellulase. Utilizing hydrolysate as carbon source, butanol titer of 10.4 g·L–1 was achieved with butanol yield of 137 g·kg–1 pretreated corncob by Clostridium saccharobutylicum DSM13864.Conclusions: Ethylamine and lactic acid based deep eutectic solvent is promising in pretreatment of corncob with high total sugar concentrations and compatible for biobutanol fermentation. This study provides an efficient pretreatment reagent for facilely reducing recalcitrance of lignocellulosic materials and a promising process for biobutanol fermentation from renewable biomass.

Optimization of Pre-treatment Using RSM on Wheat Straw and Production of Lactic Acid Using Thermotolerant, Inhibitor Tolerant and Xylose Utilizing Bacillus Sonorenesis Strain DGS15

2022 ◽  
Author(s):  
Simarpreet Kaur Chawla ◽  
Dinesh Goyal
Keyword(s):  
Lactic Acid ◽  
Wheat Straw ◽  
Lignocellulosic Biomass ◽  
Fermentation Broth ◽  
Lactic Acid Production ◽  
Reducing Sugar ◽  
Hot Water ◽  
Pre Treatment ◽  
Wheat Straw Biomass ◽  
Pretreated Biomass

Abstract Thermotolerant lactic acid producing bacteria, isolated from red soil of brick kiln was identified by 16S rRNA sequencing as Bacillus sonorenesis , which showed remarkable capability to ferment sugars of lignocellulosic biomass after pre-treatment, yielding 0.97 g/g lactic acid with overall productivity of 0.38 g L -1/ h. RSM was employed to optimize the sulphuric acid pre-treatment combined with dilute NaOH and hot water pre-treatment. Pretreated wheat straw biomass had 40.4% cellulose, 18.4% hemicellulose, 12.4% lignin and 28.2 g L -1 reducing sugar, while native wheat straw biomass had 36% cellulose, 25% hemicellulose, 20% total lignin, and 0.94 g L -1 reducing sugar. Scanning electron microscopy (SEM) revealed that the ordered and compact structure of wheat straw was destroyed upon pre-treatment. X-ray diffractogram (XRD) revealed 9.71% increase in crystallinity index ( CrI ) in pretreated biomass. FTIR spectrogram showed removal of lignin due to reduction of peak at 1640 cm -1 in pretreated biomass. Bacillus sonorenesis DGS15 is inhibitor tolerant (furfural (1.2 g L -1 ) and HMF (2.4 g L -1 )). Furfural was consumed after 72 h of fermentation and HMF got accumulated with 3.75-fold increase in concentration in the fermentation broth. In terms of final concentration, yield, and fermentation duration, this is the best performance of DGS15 for lactic acid production utilizing xylose, glucose as the carbon source. All of these findings showed that the thermotolerant Bacillus sonorenesis strain DGS15 is a novel, attractive candidate for producing lactic acid from lignocellulosic biomass.

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