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Author |
Sóti, V. |
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Title |
Catalytic detoxification of lignocellulose hydrolyzate |
Type |
Doctoral thesis |
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Year  |
2019 |
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Pages |
XXVII, 243 p. |
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Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Biochemical Wastewater Valorization & Engineering (BioWaVE) |
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Abstract |
The present PhD research investigated the possibility of catalytic detoxification of poplar wood based and steam exploded lignocellulosic hydrolyzate with different types of laccase enzymes, with special focus on ethanol and lactic acid products at industrially relevant parameters: high final product concentration, high initial substrate loading and integrated processes. The simultaneous saccharification and fermentation (SSF) process was taken as a base case and five types of laccases were thoroughly investigated on their utilization potential. Phenolic removal from the liquid xylose rich fraction (XRF) was higher with fungal laccases (65-90 %) compared to approximately 30 % removal with bacterial laccase. Moreover, the optimal pH of fungal laccases was close to pH 4.5, the optimum for cellulase, while the bacterial laccase worked at basic pH. Integrating laccase treatment and hydrolysis together showed that fungal laccases have negative impact on final sugar concentration, while bacterial laccase had a strong positive effect. Although bacterial laccase removed less phenol and although its optimal conditions are difficult to integrate with hydrolysis, its enhancing effect on cellulase activity makes it a better candidate for application. The presence of the solid fraction (SF) alters the phenolic concentration evolution significantly, thus screening experiments with the liquid fraction alone do not provide sufficient information for the combined process. Magnetic Cross-Linked Enzyme Aggregates (m-CLEAs) immobilization was assessed for bacterial laccase. m-CLEAs decreased phenolic concentration faster at every pH compared to free bacterial laccase; however, the removal was caused by adsorption rather than by enzyme activity. Although the size of m-CLEAs particles are in the µm range, around 90 % of the initial catalyst mass was recycled from a dense (15 % substrate loading) mixture via magnetic separation. The high recycling rate is promising; m-CLEAs immobilization method can have industrial utilization potential. Minimum sugar revenue (MSR) estimations show that currently hardwood based MSR is 70 % more expensive than corn grain based MSR. About 7-10 fold cellulase activity increase will be needed until MSR will be competitive with corn grain MSR. However, m-CLEAs cellulase can already be competitive if the corn prices are in the higher regime of last year’s prices. |
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Call Number |
UA @ admin @ c:irua:180125 |
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7584 |
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Author |
Sóti, V.; Lenaerts, S.; Cornet, I. |
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Title |
Of enzyme use in cost-effective high solid simultaneous saccharification and fermentation processes |
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A1 Journal article |
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Year |
2018 |
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Journal of biotechnology |
Abbreviated Journal |
J Biotechnol |
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270 |
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270 |
Pages |
70-76 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Biochemical Wastewater Valorization & Engineering (BioWaVE) |
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Abstract |
Enzyme cost is considered to be one of the most significant factors defining the final product price in lignocellulose hydrolysis and fermentation. Enzyme immobilization and recycling can be a tool to decrease costs. However, high solid loading is a key factor towards high product titers, and recovery of immobilized enzymes from this thick liquid is often overlooked. This paper aims to evaluate the economic feasibility of immobilized enzymes in simultaneous saccharification and fermentation (SSF) of lignocellulose biomass in general, as well as the recuperation of magnetic immobilized enzymes (m-CLEAs) during high solid loading in simultaneous saccharification, detoxification and fermentation processes (SSDF) of lignocellulose biomass. Enzyme prices were obtained from general cost estimations by Klein-Marcuschamer et al. [Klein-Marcuschamer et al. (2012) Biotechnol. Bioeng. 109, 10831087]. During enzyme cost analysis, the influence of inoculum recirculation as well as a shortened fermentation time was explored. Both resulted in 15% decrease of final enzyme product price. Enzyme recuperation was investigated experimentally and 99.5 m/m% of m-CLEAs was recovered from liquid medium in one step, while 88 m/m% could still be recycled from a thick liquid with high solid concentrations (SSF fermentation broth). A mathematical model was constructed to calculate the cost of immobilized and free enzyme utilization and showed that, with current process efficiencies and commercial enzyme prices, the cost reduction obtained by enzyme immobilization can reach around 60% compared to free enzyme utilization, while lower enzyme prices will result in a lower percentage of immobilization related savings, but overall enzyme costs will decrease significantly. These results are applied in a case study, estimating the viability of shifting from sugar to lignocellulose substrate for a 100 t lactic acid fermentation batch. It was concluded that it will only be economically feasible if the enzymes are produced at the most optimistic variable cost and either the activity of the immobilized catalyst or the recovery efficiency is further increased. |
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000427556400009 |
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2018-02-08 |
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ISSN |
0168-1656 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.599 |
Times cited |
6 |
Open Access |
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Notes |
; This research is financed by the University of Antwerp [project number 15 FA100 002]. ; |
Approved |
Most recent IF: 2.599 |
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Call Number |
UA @ admin @ c:irua:149006 |
Serial |
5974 |
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Sóti, V.; Jacquet, N.; Apers, S.; Richel, A.; Lenaerts, S.; Cornet, I. |
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Title |
Monitoring the laccase reaction of vanillin and poplar hydrolysate |
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A1 Journal article |
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Year |
2016 |
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Journal of chemical technology and biotechnology |
Abbreviated Journal |
J Chem Technol Biot |
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91 |
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6 |
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1914-1922 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Biochemical Wastewater Valorization & Engineering (BioWaVE) |
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BACKGROUND Laccase is an intensively researched enzyme for industrial use. Except for decolorisation measurements, HPLC analysis is the conventional method for monitoring the phenolic removal during laccase enzyme reaction. This paper reports an investigation of the continuous UV absorbance follow-up of the laccase reaction with steam pretreated poplar hydrolysate. RESULTS Vanillin was used as a model substrate and lignocellulose xylose rich fraction (XRF) as a biologically complex substrate for laccase detoxification. The reaction was followed by HPLC-UV as well as by UV spectrometric measurements. Results suggest that the reaction can be successfully monitored by measuring the change of UV absorbance at 280 nm, without previous compound separation. In case of XRF experiments the spectrophotometric follow-up is especially useful, as HPLC analysis takes a long time and provides less information than in case of single substrates. The method seems to be suitable for optimization and process control. CONCLUSION The obtained results can help to construct a fast, easy and straightforward monitoring system for laccase-phenolic substrate reactions. |
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000375768300040 |
Publication Date |
2015-07-29 |
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0268-2575; 1097-4660 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.135 |
Times cited |
3 |
Open Access |
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Notes |
; This research is financed by the University of Antwerp (project number 15 FA100 002). ; |
Approved |
Most recent IF: 3.135 |
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Call Number |
UA @ admin @ c:irua:127694 |
Serial |
5972 |
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