Publications by authors named "Sujit Sadashiv Jagtap"

16 Publications

  • Page 1 of 1

Investigating the role of the transcriptional regulator Ure2 on the metabolism of Saccharomyces cerevisiae: a multi-omics approach.

Appl Microbiol Biotechnol 2021 Jun 21;105(12):5103-5112. Epub 2021 Jun 21.

DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, USA.

Ure2 regulates nitrogen catabolite repression in Saccharomyces cerevisiae. Deletion of URE2 induces a physiological state mimicking the nitrogen starvation and autophagic responses. Previous work has shown that deletion of URE2 increases the fermentation rate of some wine-producing strains of S. cerevisiae. In this work, we investigated the effect of URE2 deletion (ΔURE2) on the metabolism of S. cerevisiae. During growth on glucose, the ΔURE2 mutant grew at a 40% slower rate than the wild type; however, it produced ethanol at a 31% higher rate. To better under the behavior of this mutant, we performed transcriptomics and metabolomics. Analysis of the RNA sequencing results and metabolite levels indicates that the mutant strain exhibited characteristics of both nitrogen starvation and autophagy, including the upregulation of allantoin, urea, and amino acid uptake and utilization pathways and selective autophagic machinery. In addition, pyruvate decarboxylase and alcohol dehydrogenase isoforms were expressed at higher rates than the wild type. The mutant also accumulated less trehalose and glycogen, and produced more lipids. The induction of a nitrogen starvation-like state and increase in lipid production in nitrogen-rich conditions suggest that URE2 may be a promising target for metabolic engineering in S. cerevisiae and other yeasts for the production of lipids and lipid-derived compounds. KEY POINTS: • Deletion of URE2 increases ethanol and lipid production in Saccharomyces cerevisiae. • Deletion of URE2 reduces glycogen and trehalose production. • Metabolic changes mimic nitrogen starvation and autophagic response.
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http://dx.doi.org/10.1007/s00253-021-11394-9DOI Listing
June 2021

Renewable biohydrogen production from lignocellulosic biomass using fermentation and integration of systems with other energy generation technologies.

Sci Total Environ 2021 Apr 24;765:144429. Epub 2020 Dec 24.

Department of Biological Engineering, College of Engineering, Konkuk University, Seoul 05029, Republic of Korea; Institute for Ubiquitous Information Technology and Application, Konkuk University, Seoul 05029, Republic of Korea. Electronic address:

Biohydrogen is a clean and renewable source of energy. It can be produced by using technologies such as thermochemical, electrolysis, photoelectrochemical and biological, etc. Among these technologies, the biological method (dark fermentation) is considered more sustainable and ecofriendly. Dark fermentation involves anaerobic microbes which degrade carbohydrate rich substrate and produce hydrogen. Lignocellulosic biomass is an abundantly available raw material and can be utilized as an economic and renewable substrate for biohydrogen production. Although there are many hurdles, continuous advancements in lignocellulosic biomass pretreatment technology, microbial fermentation (mixed substrate and co-culture fermentation), the involvement of molecular biology techniques, and understanding of various factors (pH, T, addition of nanomaterials) effect on biohydrogen productivity and yield render this technology efficient and capable to meet future energy demands. Further integration of biohydrogen production technology with other products such as bio-alcohol, volatile fatty acids (VFAs), and methane have the potential to improve the efficiency and economics of the overall process. In this article, various methods used for lignocellulosic biomass pretreatment, technologies in trends to produce and improve biohydrogen production, a coproduction of other energy resources, and techno-economic analysis of biohydrogen production from lignocellulosic biomass are reviewed.
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http://dx.doi.org/10.1016/j.scitotenv.2020.144429DOI Listing
April 2021

Recent developments in pretreatment technologies on lignocellulosic biomass: Effect of key parameters, technological improvements, and challenges.

Bioresour Technol 2020 Mar 2;300:122724. Epub 2020 Jan 2.

Department of Biological Engineering, College of Engineering, Konkuk University, Seoul 05029, Republic of Korea; Institute for Ubiquitous Information Technology and Application, Konkuk University, Seoul 05029, Republic of Korea. Electronic address:

Lignocellulosic biomass is an inexpensive renewable source that can be used to produce biofuels and bioproducts. The recalcitrance nature of biomass hampers polysaccharide accessibility for enzymes and microbes. Several pretreatment methods have been developed for the conversion of lignocellulosic biomass into value-added products. However, these pretreatment methods also produce a wide range of secondary compounds, which are inhibitory to enzymes and microorganisms. The selection of an effective and efficient pretreatment method discussed in the review and its process optimization can significantly reduce the production of inhibitory compounds and may lead to enhanced production of fermentable sugars and biochemicals. Moreover, evolutionary and genetic engineering approaches are being used for the improvement of microbial tolerance towards inhibitors. Advancements in pretreatment and detoxification technologies may help to increase the productivity of lignocellulose-based biorefinery. In this review, we discuss the recent advancements in lignocellulosic biomass pretreatment technologies and strategies for the removal of inhibitors.
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http://dx.doi.org/10.1016/j.biortech.2019.122724DOI Listing
March 2020

Production of galactitol from galactose by the oleaginous yeast IFO0880.

Biotechnol Biofuels 2019 18;12:250. Epub 2019 Oct 18.

1Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL 61801 USA.

Background: Sugar alcohols are commonly used as low-calorie sweeteners and can serve as potential building blocks for bio-based chemicals. Previous work has shown that the oleaginous yeast IFO0880 can natively produce arabitol from xylose at relatively high titers, suggesting that it may be a useful host for sugar alcohol production. In this work, we explored whether can produce additional sugar alcohols.

Results: is able to produce galactitol from galactose. During growth in nitrogen-rich medium, produced 3.2 ± 0.6 g/L, and 8.4 ± 0.8 g/L galactitol from 20 to 40 g/L galactose, respectively. In addition, was able to produce galactitol from galactose at reduced titers during growth in nitrogen-poor medium, which also induces lipid production. These results suggest that can potentially be used for the co-production of lipids and galactitol from galactose. We further characterized the mechanism for galactitol production, including identifying and biochemically characterizing the critical aldose reductase. Intracellular metabolite analysis was also performed to further understand galactose metabolism.

Conclusions: has traditionally been used for the production of lipids and lipid-based chemicals. Our work demonstrates that can also produce galactitol, which can be used to produce polymers with applications in medicine and as a precursor for anti-cancer drugs. Collectively, our results further establish that can produce multiple value-added chemicals from a wide range of sugars.
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http://dx.doi.org/10.1186/s13068-019-1586-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6798376PMC
October 2019

pH selectively regulates citric acid and lipid production in Yarrowia lipolytica W29 during nitrogen-limited growth on glucose.

J Biotechnol 2019 Jan 26;290:10-15. Epub 2018 Nov 26.

Department of Chemical and Biomolecular Engineering, DOE Center for Advanced Bioenergy and Bioproducts Innovation, Carl R. Woese Institute of Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. Electronic address:

Yarrowia lipolytica has been used to produce both citric acid and lipid-based bioproducts at high titers. In this study, we found that pH differentially affects citric acid and lipid production in Y. lipolytica W29, with citric acid production enhanced at more neutral pH's and lipid production enhanced at more acid pH's. To determine the mechanism governing this pH-dependent switch between citric acid and lipid production, we profiled gene expression at different pH's and found that the relative expression of multiple transporters is increased at neutral pH. These results suggest that this pH-dependent switch is mediated at the level of citric acid transport rather than changes in the expression of the enzymes involved in citric acid and lipid metabolism. In further support of this mechanism, thermodynamic calculations suggest that citric acid secretion is more energetically favorable at neutral pH's, assuming the fully protonated acid is the substrate for secretion. Collectively, these results provide new insights regarding citric acid and lipid production in Y. lipolytica and may offer new strategies for metabolic engineering and process design.
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http://dx.doi.org/10.1016/j.jbiotec.2018.10.012DOI Listing
January 2019

Microbial conversion of xylose into useful bioproducts.

Appl Microbiol Biotechnol 2018 Nov 24;102(21):9015-9036. Epub 2018 Aug 24.

Department of Chemical and Biomolecular Engineering, DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave, Urbana, IL, 61801, USA.

Microorganisms can produce a number of different bioproducts from the sugars in plant biomass. One challenge is devising processes that utilize all of the sugars in lignocellulosic hydrolysates. D-xylose is the second most abundant sugar in these hydrolysates. The microbial conversion of D-xylose to ethanol has been studied extensively; only recently, however, has conversion to bioproducts other than ethanol been explored. Moreover, in the case of yeast, D-xylose may provide a better feedstock for the production of bioproducts other than ethanol, because the relevant pathways are not subject to glucose-dependent repression. In this review, we discuss how different microorganisms are being used to produce novel bioproducts from D-xylose. We also discuss how D-xylose could be potentially used instead of glucose for the production of value-added bioproducts.
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http://dx.doi.org/10.1007/s00253-018-9294-9DOI Listing
November 2018

Production of D-arabitol from D-xylose by the oleaginous yeast Rhodosporidium toruloides IFO0880.

Appl Microbiol Biotechnol 2018 Jan 11;102(1):143-151. Epub 2017 Nov 11.

Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA.

The sugar alcohol D-arabitol is one of the Department of Energy's top twelve bio-based building block chemicals. In this study, we found that the oleaginous yeast Rhodosporidium toruloides IFO0880 produces D-arabitol during growth on xylose in nitrogen-rich medium. Efficient xylose utilization was a prerequisite for extracellular D-arabitol production. During growth in complex media, R. toruloides produced 22 ± 2, 32 ± 2, and 49 ± 2 g/L D-arabitol from 70, 105, and 150 g/L xylose, respectively. In addition, we found that R. toruloides could potentially be used for the co-production of lipids and D-arabitol from xylose. These results demonstrate that R. toruloides can be used to produce multiple value-added chemicals from xylose.
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http://dx.doi.org/10.1007/s00253-017-8581-1DOI Listing
January 2018

Exploiting fine-scale genetic and physiological variation of closely related microbes to reveal unknown enzyme functions.

J Biol Chem 2017 08 7;292(31):13056-13067. Epub 2017 Jun 7.

Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801. Electronic address:

Polysaccharide degradation by marine microbes represents one of the largest and most rapid heterotrophic transformations of organic matter in the environment. Microbes employ systems of complementary carbohydrate-specific enzymes to deconstruct algal or plant polysaccharides (glycans) into monosaccharides. Because of the high diversity of glycan substrates, the functions of these enzymes are often difficult to establish. One solution to this problem may lie within naturally occurring microdiversity; varying numbers of enzymes, due to gene loss, duplication, or transfer, among closely related environmental microbes create metabolic differences akin to those generated by knock-out strains engineered in the laboratory used to establish the functions of unknown genes. Inspired by this natural fine-scale microbial diversity, we show here that it can be used to develop hypotheses guiding biochemical experiments for establishing the role of these enzymes in nature. In this work, we investigated alginate degradation among closely related strains of the marine bacterium One strain, 13B01, exhibited high extracellular alginate lyase activity compared with other strains. To identify the enzymes responsible for this high extracellular activity, we compared 13B01 with the previously characterized 12B01, which has low extracellular activity and lacks two alginate lyase genes present in 13B01. Using a combination of genomics, proteomics, biochemical, and functional screening, we identified a polysaccharide lyase family 7 enzyme that is unique to 13B01, secreted, and responsible for the rapid digestion of extracellular alginate. These results demonstrate the value of querying the enzymatic repertoires of closely related microbes to rapidly pinpoint key proteins with beneficial functions.
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http://dx.doi.org/10.1074/jbc.M117.787192DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5546043PMC
August 2017

Alginate lyases from alginate-degrading Vibrio splendidus 12B01 are endolytic.

Appl Environ Microbiol 2015 Mar 2;81(5):1865-73. Epub 2015 Jan 2.

Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA

Alginate lyases are enzymes that degrade alginate through β-elimination of the glycosidic bond into smaller oligomers. We investigated the alginate lyases from Vibrio splendidus 12B01, a marine bacterioplankton species that can grow on alginate as its sole carbon source. We identified, purified, and characterized four polysaccharide lyase family 7 alginates lyases, AlyA, AlyB, AlyD, and AlyE, from V. splendidus 12B01. The four lyases were found to have optimal activity between pH 7.5 and 8.5 and at 20 to 25°C, consistent with their use in a marine environment. AlyA, AlyB, AlyD, and AlyE were found to exhibit a turnover number (kcat) for alginate of 0.60 ± 0.02 s(-1), 3.7 ± 0.3 s(-1), 4.5 ± 0.5 s(-1), and 7.1 ± 0.2 s(-1), respectively. The Km values of AlyA, AlyB, AlyD, and AlyE toward alginate were 36 ± 7 μM, 22 ± 5 μM, 60 ± 2 μM, and 123 ± 6 μM, respectively. AlyA and AlyB were found principally to cleave the β-1,4 bonds between β-d-mannuronate and α-l-guluronate and subunits; AlyD and AlyE were found to principally cleave the α-1,4 bonds involving α-l-guluronate subunits. The four alginate lyases degrade alginate into longer chains of oligomers.
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http://dx.doi.org/10.1128/AEM.03460-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4325137PMC
March 2015

Comparative biochemical characterization of three exolytic oligoalginate lyases from Vibrio splendidus reveals complementary substrate scope, temperature, and pH adaptations.

Appl Environ Microbiol 2014 Jul 2;80(14):4207-14. Epub 2014 May 2.

Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA

Marine microbes use alginate lyases to degrade and catabolize alginate, a major cell wall matrix polysaccharide of brown seaweeds. Microbes frequently contain multiple, apparently redundant alginate lyases, raising the question of whether these enzymes have complementary functions. We report here on the molecular cloning and functional characterization of three exo-type oligoalginate lyases (OalA, OalB, and OalC) from Vibrio splendidus 12B01 (12B01), a marine bacterioplankton species. OalA was most active at 16°C, had a pH optimum of 6.5, and displayed activities toward poly-β-d-mannuronate [poly(M)] and poly-α-l-guluronate [poly(G)], indicating that it is a bifunctional enzyme. OalB and OalC were most active at 30 and 35°C, had pH optima of 7.0 and 7.5, and degraded poly(M·G) and poly(M), respectively. Detailed kinetic analyses of oligoalginate lyases with poly(G), poly(M), and poly(M·G) and sodium alginate as substrates demonstrated that OalA and OalC preferred poly(M), whereas OalB preferred poly(M·G). The catalytic efficiency (kcat/Km) of OalA against poly(M) increased with decreasing size of the substrate. OalA showed kcat/Km from 2,130 mg(-1) ml s(-1) for the trisaccharide to 224 mg(-1) ml s(-1) for larger oligomers of ∼50 residues, and 50.5 mg(-1) ml s(-1) for high-molecular-weight alginate. Although OalA was most active on the trisaccharide, OalB and OalC preferred dimers. Taken together, our results indicate that these three Oals have complementary substrate scopes and temperature and pH adaptations.
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http://dx.doi.org/10.1128/AEM.01285-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4068682PMC
July 2014

Cloning and characterization of a galactitol 2-dehydrogenase from Rhizobium legumenosarum and its application in D-tagatose production.

Enzyme Microb Technol 2014 May 12;58-59:44-51. Epub 2014 Mar 12.

Department of Chemical Engineering, Konkuk University, Seoul 143-701, Republic of Korea. Electronic address:

Galactitol 2-dehydrogenase (GDH) belongs to the protein subfamily of short-chain dehydrogenases/reductases and can be used to produce optically pure building blocks and for the bioconversion of bioactive compounds. An NAD(+)-dependent GDH from Rhizobium leguminosarum bv. viciae 3841 (RlGDH) was cloned and overexpressed in Escherichia coli. The RlGDH protein was purified as an active soluble form using His-tag affinity chromatography. The molecular mass of the purified enzyme was estimated to be 28kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 114kDa by gel filtration chromatography, suggesting that the enzyme is a homotetramer. The enzyme has an optimal pH and temperature of 9.5 and 35°C, respectively. The purified recombinant RlGDH catalyzed the oxidation of a wide range of substrates, including polyvalent aliphatic alcohols and polyols, to the corresponding ketones and ketoses. Among various polyols, galactitol was the preferred substrate of RlGDH with a Km of 8.8mM, kcat of 835min(-1) and a kcat/Km of 94.9min(-1)mM(-1). Although GDHs have been characterized from a few other sources, RlGDH is distinguished from other GDHs by its higher specific activity for galactitol and broad substrate spectrum, making RlGDH a good choice for practical applications.
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http://dx.doi.org/10.1016/j.enzmictec.2014.02.012DOI Listing
May 2014

Characterization of a novel endo-β-1,4-glucanase from Armillaria gemina and its application in biomass hydrolysis.

Appl Microbiol Biotechnol 2014 Jan 21;98(2):661-9. Epub 2013 Apr 21.

Department of Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul, 143-701, Republic of Korea.

A novel endo-β-1,4-glucanase (EG)-producing strain was isolated and identified as Armillaria gemina KJS114 based on its morphology and internal transcribed spacer rDNA gene sequence. A. gemina EG (AgEG) was purified using a single-step purification by gel filtration. The relative molecular mass of AgEG by sodium dodecyl sulfate polyacrylamide gel electrophoresis was 65 kDa and by size exclusion chromatography was 66 kDa, indicating that the enzyme is a monomer in solution. The pH and temperature optima for hydrolysis were 5.0 and 60 °C, respectively. Purified AgEG had the highest catalytic efficiency with carboxymethylcellulose (k(cat)/K(m) = 3,590 mg mL⁻¹ s⁻¹) unlike that reported for any fungal EG, highlighting the significance of the current study. The amino acid sequence of AgEG showed homology with hydrolases from the glycoside hydrolase family 61. The addition of AgEG to a Populus nigra hydrolysate reaction containing a commercial cellulase mixture (Celluclast 1.5L and Novozyme 188) showed a stimulatory effect on reducing sugar production. AgEG is a good candidate for applications that convert lignocellulosic biomass to biofuels and chemicals.
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http://dx.doi.org/10.1007/s00253-013-4894-xDOI Listing
January 2014

Enzymatic hydrolysis of aspen biomass into fermentable sugars by using lignocellulases from Armillaria gemina.

Bioresour Technol 2013 Apr 30;133:307-14. Epub 2013 Jan 30.

Department of Chemical Engineering, Konkuk University, Seoul 143-701, Republic of Korea.

A white rot fungus, identified as Armillaria gemina SKU2114 on the basis of morphological and phylogenetic analyses, was found to secrete efficient lignocellulose-degrading enzymes. The strain showed maximum endoglucanase, cellobiohydrolase, and β-glucosidase activities of 146, 34, and 15 U/mL, respectively, and also secreted xylanase, laccase, mannanase, and lignin peroxidase with activities of 1270, 0.16, 57, and 0.31 U/mL, respectively, when grown with rice straw as a carbon source. Among various plant biomasses tested for saccharification, aspen biomass produced the maximum amount of reducing sugar. Response surface methodology was used to optimize the hydrolysis of aspen biomass to achieve the highest level of sugar production. A maximum saccharification yield of 62% (429 mg/g-substrate) was obtained using Populus tomentiglandulosa biomass after 48 h of hydrolysis. A. gemina was shown to be a good option for use in the production of reducing sugars from lignocellulosic biomass.
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http://dx.doi.org/10.1016/j.biortech.2013.01.118DOI Listing
April 2013

Characterization of a novel xylanase from Armillaria gemina and its immobilization onto SiO2 nanoparticles.

Appl Microbiol Biotechnol 2013 Feb 7;97(3):1081-91. Epub 2012 Sep 7.

Department of Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul, 143-701, Republic of Korea.

Enhanced catalytic activities of different lignocellulases were obtained from Armillaria gemina under statistically optimized parameters using a jar fermenter. This strain showed maximum xylanase, endoglucanase, cellobiohydrolase, and β-glucosidase activities of 1,270, 146, 34, and 15 U mL(-1), respectively. Purified A. gemina xylanase (AgXyl) has the highest catalytic efficiency (k (cat)/K (m) = 1,440 mg mL(-1) s(-1)) ever reported for any fungal xylanase, highlighting the significance of the current study. We covalently immobilized the crude xylanase preparation onto functionalized silicon oxide nanoparticles, achieving 117 % immobilization efficiency. Further immobilization caused a shift in the optimal pH and temperature, along with a fourfold improvement in the half-life of crude AgXyl. Immobilized AgXyl gave 37.8 % higher production of xylooligosaccharides compared to free enzyme. After 17 cycles, the immobilized enzyme retained 92 % of the original activity, demonstrating its potential for the synthesis of xylooligosaccharides in industrial applications.
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http://dx.doi.org/10.1007/s00253-012-4381-9DOI Listing
February 2013

Saccharification of poplar biomass by using lignocellulases from Pholiota adiposa.

Bioresour Technol 2012 Sep 12;120:264-72. Epub 2012 Jun 12.

Department of Chemical Engineering, Konkuk University, Seoul 143-701, Republic of Korea.

A basidiomycetous fungus, identified as Pholiota adiposa SKU0714 on the basis of morphological and phylogenetic analyses, was found to secrete efficient lignocellulose degrading enzymes. The strain showed maximum endoglucanase, cellobiohydrolase and β-glucosidase activities of 26, 32 and 39 U/mL, respectively and also secreted xylanase, laccase, mannanase, and lignin peroxidase with activities of 1680, 0.12, 65 and 0.41 U/mL, respectively when grown with rice straw as a carbon source. Among the various plant biomasses tested for saccharification, poplar biomass produced the maximum amount of reducing sugar. Response surface methodology was used to optimize hydrolysis parameters. A maximum saccharification yield of 83.4% (667 mg/g-substrate), the highest yield from any plant biomass, was obtained with Populus biomass after 24h of hydrolysis. P. adiposa was proven to be a good choice for the production of reducing sugars from cellulosic biomass.
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http://dx.doi.org/10.1016/j.biortech.2012.06.002DOI Listing
September 2012

Immobilization of Pholiota adiposa xylanase onto SiO₂ nanoparticles and its application for production of xylooligosaccharides.

Biotechnol Lett 2012 Jul 16;34(7):1307-13. Epub 2012 Mar 16.

Department of Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul 143-701, Republic of Korea.

Enhanced yields of different lignocellulases were obtained under statistically-optimized parameters using Pholiota adiposa. The k (cat) value (4,261 s(-1)) of purified xylanase under standard assay conditions was the highest value ever reported. On covalent immobilization of the crude xylanase preparation onto functionalized silicon oxide nanoparticles, 66 % of the loaded enzyme was retained on the particle. Immobilized enzyme gave 45 % higher concentrations of xylooligosaccharides compared to the free enzyme. After 17 cycles, the immobilized enzyme retained 97 % of the original activity, demonstrating its prospects for the synthesis of xylooligosaccharides in industrial applications.
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http://dx.doi.org/10.1007/s10529-012-0902-yDOI Listing
July 2012
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