1
|
Rai R, Samanta D, Goh KM, Chadha BS, Sani RK. Biochemical unravelling of the endoxylanase activity in a bifunctional GH39 enzyme cloned and expressed from thermophilic Geobacillus sp. WSUCF1. Int J Biol Macromol 2024; 257:128679. [PMID: 38072346 DOI: 10.1016/j.ijbiomac.2023.128679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 11/30/2023] [Accepted: 12/06/2023] [Indexed: 01/27/2024]
Abstract
The glycoside hydrolase family 39 (GH39) proteins are renowned for their extremophilic and multifunctional enzymatic properties, yet the molecular mechanisms underpinning these unique characteristics continue to be an active subject of research. In this study, we introduce WsuXyn, a GH39 protein with a molecular weight of 58 kDa, originating from the thermophilic Geobacillus sp. WSUCF1. Previously reported for its exceptional thermostable β-xylosidase activity, WsuXyn has recently demonstrated a significant endoxylanase activity (3752 U·mg-1) against beechwood xylan, indicating towards its bifunctional nature. Physicochemical characterization revealed that WsuXyn exhibits optimal endoxylanase activity at 70 °C and pH 7.0. Thermal stability assessments revealed that the enzyme is resilient to elevated temperatures, with a half-life of 168 h. Key kinetic parameters highlight the exceptional catalytic efficiency and strong affinity of the protein for xylan substrate. Moreover, WsuXyn-mediated hydrolysis of beechwood xylan has achieved 77 % xylan conversion, with xylose as the primary product. Structural analysis, amalgamated with docking simulations, has revealed strong binding forces between xylotetraose and the protein, with key amino acid residues, including Glu278, Tyr230, Glu160, Gly202, Cys201, Glu324, and Tyr283, playing pivotal roles in these interactions. Therefore, WsuXyn holds a strong promise for biodegradation and value-added product generation through lignocellulosic biomass conversion.
Collapse
Affiliation(s)
- Rohit Rai
- Faculty of Applied Medical Sciences, Lovely Professional University, Phagwara 144411, India.
| | - Dipayan Samanta
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA
| | - Kian Mau Goh
- Faculty of Science, Universiti Teknologi Malaysia, Johor 81310, Malaysia
| | | | - Rajesh K Sani
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA; BuG ReMeDEE consortium and Composite and Nanocomposite Advanced Manufacturing Centre/Biomaterials (CNAM/Bio), Rapid City, SD 57701, USA.
| |
Collapse
|
2
|
El-Gendi H, Badawy AS, Bakhiet EK, Rawway M, Ali SG. Valorization of lignocellulosic wastes for sustainable xylanase production from locally isolated Bacillus subtilis exploited for xylooligosaccharides' production with potential antimicrobial activity. Arch Microbiol 2023; 205:315. [PMID: 37605001 PMCID: PMC10442310 DOI: 10.1007/s00203-023-03645-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 06/21/2023] [Accepted: 07/30/2023] [Indexed: 08/23/2023]
Abstract
The worldwide availability of lignocellulosic wastes represents a serious environmental challenge with potential opportunities. Xylanases are crucial in lignocellulosic bio-hydrolysis, but the low enzyme productivity and stability are still challenges. In the current study, Bacillus subtilis (coded ARSE2) revealed potent xylanase activity among other local isolates. The enzyme production optimization revealed that maximum enzyme production (490.58 U/mL) was achieved with 1% xylan, 1.4% peptone, and 5% NaCl at 30 °C and pH 9. Furthermore, several lignocellulosic wastes were exploited for sustainable xylanase production, where sugarcane bagasse (16%) under solid-state fermentation and woody sawdust (2%) under submerged fermentation supported the maximum enzyme titer of about 472.03 and 485.7 U/mL, respectively. The partially purified enzyme revealed two protein bands at 42 and 30 kDa. The partially purified enzyme revealed remarkable enzyme activity and stability at 50-60 °C and pH 8-9. The enzyme also revealed significant stability toward tween-80, urea, DTT, and EDTA with Vmax and Km values of 1481.5 U/mL and 0.187 mM, respectively. Additionally, the purified xylanase was applied for xylooligosaccharides production, which revealed significant antimicrobial activity toward Staphylococcus aureus with lower activity against Escherichia coli. Hence, the locally isolated Bacillus subtilis ARSE2 could fulfill the xylanase production requirements in terms of economic production at a high titer with promising enzyme characteristics. Additionally, the resultant xylooligosaccharides revealed a promising antimicrobial potential, which paves the way for other medical applications.
Collapse
Affiliation(s)
- Hamada El-Gendi
- Bioprocess Development Department, Genetic Engineering and Biotechnology Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab City, Alexandria, 21934, Egypt.
| | - Ahmed S Badawy
- Botany and Microbiology Department, Faculty of Science, AL-Azhar University, Assiut, Egypt
| | - Elsayed K Bakhiet
- Botany and Microbiology Department, Faculty of Science, AL-Azhar University, Assiut, Egypt
| | - Mohammed Rawway
- Botany and Microbiology Department, Faculty of Science, AL-Azhar University, Assiut, Egypt
| | - Salah G Ali
- Botany and Microbiology Department, Faculty of Science, AL-Azhar University, Assiut, Egypt
| |
Collapse
|
3
|
Sürmeli Y, Şanlı-Mohamed G. Engineering of xylanases for the development of biotechnologically important characteristics. Biotechnol Bioeng 2023; 120:1171-1188. [PMID: 36715367 DOI: 10.1002/bit.28339] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/19/2022] [Accepted: 01/26/2023] [Indexed: 01/31/2023]
Abstract
Xylanases are the main biocatalysts used for the reduction of the xylan backbone from hemicellulose, randomly splitting off β-1,4-glycosidic linkages between xylopyranosyl residues. Xylanase market has been annually estimated at 500 million US Dollars and they are potentially used in broad industrial process ranges such as paper pulp biobleaching, xylo-oligosaccharide production, and biofuel manufacture from lignocellulose. The highly stable xylanases are preferred in the downstream procedure of industrial processes because they can tolerate severe conditions. Almost all native xylanases can not endure adverse conditions thus they are industrially not proper to be utilized. Protein engineering is a powerful technology for developing xylanases, which can effectively work in adverse conditions and can meet requirements for industrial processes. This study considered state-of-the-art strategies of protein engineering for creating the xylanase gene diversity, high-throughput screening systems toward upgraded traits of the xylanases, and the prediction and comprehensive analysis of the target mutations in xylanases by in silico methods. Also, key molecular factors have been elucidated for industrial characteristics (alkaliphilic enhancement, thermal stability, and catalytic performance) of GH11 family xylanases. The present review explores industrial characteristics improved by directed evolution, rational design, and semi-rational design as protein engineering approaches for pulp bleaching process, xylooligosaccharides production, and biorefinery & bioenergy production.
Collapse
Affiliation(s)
- Yusuf Sürmeli
- Department of Agricultural Biotechnology, Tekirdağ Namık Kemal University, Tekirdağ, Turkey
| | | |
Collapse
|
4
|
Omisore SO, Fabunmi TB, Ayodeji AO, Olaniyi OO, Arotupin DJ. Production and biochemical characterization of partially purified cellulase-free, thermo-acidophilic endoxylanase from Lysinibacillus fusiformis strain TB7 using kolanut husk as feedstock. Heliyon 2022; 8:e11106. [PMID: 36281386 PMCID: PMC9586915 DOI: 10.1016/j.heliyon.2022.e11106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/25/2022] [Accepted: 10/11/2022] [Indexed: 10/29/2022] Open
Abstract
Xylanases have become very important enzymes in many industrial processes for the valorization of xylan-rich lignocellulosic wastes. Here, some physicochemical and kinetic properties of a purified endoxylanase produced on kolanut husk-based medium by Lysinibacillus fusiformis are presented. The crude enzyme solution was first subjected to precipitation with solid ammonium sulphate and further purified on DEAE-Sephadex A-50 anion-exchange and Sephadex G-100 gel filtration columns chromatography prior to biochemical characterization. The purified endoxylanase was 21 kDa as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and was thermostable, exhibiting optimum activity at 60 °C and pH 5.0. The K m and V max were respectively estimated to be 29.5 mg/ml and 125 μmol/min/ml using Birchwood xylan as substrate. Activity of the enzyme was enhanced by Na+, Ca2+, Mn2+, Mg2+ and K+ at concentration of 5 mM but inhibited by Hg2+, Cu2+, Pb2+, Fe3+, EDTA, SDS and Urea. The purified endoxylanase showed high hydrolytic activity on Birchwood xylan and kolanut husk but extremely poor or no activity on carboxymethyl cellulose, starch or pectin. This L. fusiformis strain TB7 endoxylanase has desirable properties useful for biotechnological applications in laundry, fuels, feeds, paper and pulp industries.
Collapse
Affiliation(s)
- Suliat Olatidayo Omisore
- Department of Microbiology, Federal University of Technology, P.M.B. 704, Akure, Nigeria,Corresponding author.
| | - Temitope Bukola Fabunmi
- Department of Microbiology, Federal University of Technology, P.M.B. 704, Akure, Nigeria,Department of Biological Sciences, Achievers University, P.M.B. 001, Owo, Nigeria
| | - Adeyemi Oluwadare Ayodeji
- Department of Biochemistry, Federal University of Technology, P.M.B. 704, Akure, Nigeria,Department of Chemical Sciences, Biochemistry Unit, Joseph Ayo Babalola University, Ikeji-Arakeji, P.M.B. 5006, Ilesha, Nigeria
| | | | - Daniel Juwon Arotupin
- Department of Microbiology, Federal University of Technology, P.M.B. 704, Akure, Nigeria
| |
Collapse
|
5
|
Joshi JB, Priyadharshini R, Uthandi S. Glycosyl hydrolase 11 (xynA) gene with xylanase activity from thermophilic bacteria isolated from thermal springs. Microb Cell Fact 2022; 21:62. [PMID: 35428308 PMCID: PMC9013152 DOI: 10.1186/s12934-022-01788-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 03/29/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Hemicellulose is one of the copious polymer in lignocellulosic biomass (LCB). It is primarily composed of xylan linked by β-1,4 glycosidic bonds. Xylanase preferentially cleaves the β-1,4-glycosidic bonds in the xylan backbone resulting in complete hydrolysis of the biomass. Thermostable variants of glycoside hydrolases act as robust catalysts, not only in degradation but also during processing, to obtain specific carbohydrate-containing chemicals and materials (Ramasamy et al. in Madras Agric J 107(special):1. 10.29321/MAJ.2020.000382, 2020).
Results
The xylanase production by two thermophilic bacteria isolated from thermal springs was evaluated. In addition, the gene encoding this industrially vital enzyme was isolated and characterized, and its protein structure was analyzed. The thermophilic bacteria producing xylanases were isolated from augmented sawdust and banana fiber biomass from hot springs of Himachal Pradesh and identified as Bacillus subtilis VSDB5 and Bacillus licheniformis KBFB4 using 16S rRNA gene sequencing. The persistent xylanase activity revealed that the enzyme is secreted extracellularly with the maximum activity of 0.76 IU mL−1 and 1.0 IU mL−1 at 6 h and 12 h of growth by KBFB4 and VSDB5, respectively, under submerged fermentation. Both the strains exhibited the maximum activity at pH 6 and a temperature of 50 °C. The xylanases of KBFB4 and VSDB5 were thermostable and retained 40% of their activity at 60 °C after incubation for 30 min. Xylanase of VSDB5 had wide thermotolerance and retained 20% of its activity from 60 to 80 °C, whereas xylanase of KBFB4 showed wide alkali tolerance and retained 80% of its activity until pH 10. The xylanase (xynA)-encoding gene (650 bp) cloned from both the strains using specific primers showed 98 to 99% homology to β-1,4-endoxylanase gene. Further in silico analysis predicted that the xylanase protein, with a molecular weight of 23 kDa, had a high pI (9.44–9.65), which explained the alkaline nature of the enzyme and greater aliphatic index (56.29). This finding suggested that the protein is thermostable. Multiple sequence alignment and homology modeling of the protein sequence revealed that the gene product belonged to the GH11 family, indicating its possible application in bioconversion.
Conclusion
The strains B. subtilis VSDB5 and B. licheniformis KBFB4 obtained from hot springs of Himachal Pradesh produced potent and alkali-tolerant thermostable xylanases, which belong to the GH11 family. The enzyme can be supplemented in industrial applications for biomass conversion at high temperatures and pH (or in processes involving alkali treatment).
Graphical Abstract
Collapse
|
6
|
Verma D. Extremophilic Prokaryotic Endoxylanases: Diversity, Applicability, and Molecular Insights. Front Microbiol 2021; 12:728475. [PMID: 34566933 PMCID: PMC8458939 DOI: 10.3389/fmicb.2021.728475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 08/06/2021] [Indexed: 11/13/2022] Open
Abstract
Extremophilic endoxylanases grabbed attention in recent years due to their applicability under harsh conditions of several industrial processes. Thermophilic, alkaliphilic, and acidophilic endoxylanases found their employability in bio-bleaching of paper pulp, bioconversion of lignocellulosic biomass into xylooligosaccharides, bioethanol production, and improving the nutritious value of bread and other bakery products. Xylanases obtained from extremophilic bacteria and archaea are considered better than fungal sources for several reasons. For example, enzymatic activity under broad pH and temperature range, low molecular weight, cellulase-free activity, and longer stability under extreme conditions of prokaryotic derived xylanases make them a good choice. In addition, a short life span, easy cultivation/harvesting methods, higher yield, and rapid DNA manipulations of bacterial and archaeal cells further reduces the overall cost of the product. This review focuses on the diversity of prokaryotic endoxylanases, their characteristics, and their functional attributes. Besides, the molecular mechanisms of their extreme behavior have also been presented here.
Collapse
Affiliation(s)
- Digvijay Verma
- Department of Environmental Microbiology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| |
Collapse
|
7
|
Paecilomyces variotii xylanase production, purification and characterization with antioxidant xylo-oligosaccharides production. Sci Rep 2021; 11:16468. [PMID: 34389757 PMCID: PMC8363652 DOI: 10.1038/s41598-021-95965-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 07/22/2021] [Indexed: 02/07/2023] Open
Abstract
Paecilomyces variotii xylanase was, produced in stirred tank bioreactor with yield of 760 U/mL and purified using 70% ammonium sulfate precipitation and ultra-filtration causing 3.29-fold purification with 34.47% activity recovery. The enzyme purity was analyzed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirming its monomeric nature as single band at 32 KDa. Zymography showed xylan hydrolysis activity at the same band. The purified enzyme had optimum activity at 60 °C and pH 5.0. The pH stability range was 5-9 and the temperature stability was up 70 °C. Fe2+and Fe3+ exhibited inhibition of xylanase enzyme while Cu2+, Ca2+, Mg2+ and Mn2+ stimulated its activity. Mercaptoethanol stimulated its activity; however, Na2-EDTA and SDS inhibited its activity. The purified xylanase could hydrolyze beechwood xylan but not carboxymethyl cellulose (CMC), avicel or soluble starch. Paecilomyces variotii xylanase Km and Vmax for beechwood were determined to be 3.33 mg/mL and 5555 U/mg, respectively. The produced xylanase enzyme applied on beech xylan resulted in different types of XOS. The antioxidant activity of xylo-oligosaccharides increased from 15.22 to 70.57% when the extract concentration was increased from 0.1 to 1.5 mg/mL. The enzyme characteristics and kinetic parameters indicated its high efficiency in the hydrolysis of xylan and its potential effectiveness in lignocellulosic hydrolysis and other industrial application. It also suggests the potential of xylanase enzyme for production of XOS from biomass which are useful in food and pharmaceutical industries.
Collapse
|
8
|
Boonyapakron K, Chitnumsub P, Kanokratana P, Champreda V. Enhancement of catalytic performance of a metagenome-derived thermophilic oligosaccharide-specific xylanase by binding module removal and random mutagenesis. J Biosci Bioeng 2020; 131:13-19. [PMID: 33067124 DOI: 10.1016/j.jbiosc.2020.09.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/14/2020] [Accepted: 09/15/2020] [Indexed: 10/23/2022]
Abstract
Xylo-oligosaccharide (XO) is a promising pre-biotic with applications in food, feed and healthcare products. XO can be produced by enzymatic digestion of xylan with xylanase. In this study, we aimed to improve the biochemical properties relevant to catalysis and kinetics of X11, a thermophilic glycosyl hydrolase (GH) family 11 endo-β-1,4-xylanase derived from a metagenomic library isolated from sugarcane bagasse, under high-temperature conditions preferred for XO synthesis. Removal of a carbohydrate-binding module (X11C) resulted in 6.5 fold greater catalytic efficiency. X11C was further improved by a Pro71Thr mutation in the X11P variant obtained from a random mutagenesis library, which exhibited 15.9 fold greater catalytic efficiency compared with wild-type X11 under the enzyme's optimal conditions of 80°C and pH 6.0. Homology modeling suggested that the improved performance of X11P could be attributed to formation of an extra H-bond between Thr71 and Ser75, which stabilizes the key catalytic residue Glu180 at the active pocket and β-sheet layers and agrees with the respective increase in melting temperature (Tm) where X11P >X11C >X11 as determined by differential scanning fluorimetry. The X11P variant was tested for hydrolysis of beechwood xylan, which showed X6 as the major product followed by X3 and X4 XOs. The highest yield of 5.5 g total XOs product/mg enzyme was observed for X11P, equivalent to 3.7 fold higher than that of wild-type with XO production of >800 mg/g xylan. The X11P enzyme could be developed as a thermophilic biocatalyst for XO synthesis in biorefineries.
Collapse
Affiliation(s)
- Katewadee Boonyapakron
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Penchit Chitnumsub
- Biomolecular Analysis and Application Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Pattanop Kanokratana
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Verawat Champreda
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand.
| |
Collapse
|
9
|
Verma D, Satyanarayana T. Xylanolytic Extremozymes Retrieved From Environmental Metagenomes: Characteristics, Genetic Engineering, and Applications. Front Microbiol 2020; 11:551109. [PMID: 33042057 PMCID: PMC7527525 DOI: 10.3389/fmicb.2020.551109] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 08/21/2020] [Indexed: 01/29/2023] Open
Abstract
Xylanolytic enzymes have extensive applications in paper, food, and feed, pharmaceutical, and biofuel industries. These industries demand xylanases that are functional under extreme conditions, such as high temperature, acidic/alkaline pH, and others, which are prevailing in bioprocessing industries. Despite the availability of several xylan-hydrolyzing enzymes from cultured microbes, there is a huge gap between what is available and what industries require. DNA manipulations as well as protein-engineering techniques are also not quite satisfactory in generating xylan-hydrolyzing extremozymes. With a compound annual growth rate of 6.6% of xylan-hydrolyzing enzymes in the global market, there is a need for xylanolytic extremozymes. Therefore, metagenomic approaches have been employed to uncover hidden xylanolytic genes that were earlier inaccessible in culture-dependent approaches. Appreciable success has been achieved in retrieving several unusual xylanolytic enzymes with novel and desirable characteristics from different extreme environments using functional and sequence-based metagenomic approaches. Moreover, the Carbohydrate Active Enzymes database includes approximately 400 GH-10 and GH-11 unclassified xylanases. This review discusses sources, characteristics, and applications of xylanolytic enzymes obtained through metagenomic approaches and their amelioration by genetic engineering techniques.
Collapse
Affiliation(s)
- Digvijay Verma
- Department of Microbiology, Babasaheb Bhimrao Ambedkar (Central) University, Lucknow, India
| | - Tulasi Satyanarayana
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, Dwarka, New Delhi, India
| |
Collapse
|
10
|
Bibi Z, Ansari A, Zohra RR, Aman A, Ul Qader SA. Production of xylan degrading endo-1, 4-β-xylanase from thermophilicGeobacillus stearothermophilusKIBGE-IB29. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2019. [DOI: 10.1016/j.jrras.2014.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Zainab Bibi
- The Karachi Institute of Biotechnology and Genetic Engineering (KIBGE), University of Karachi, Karachi, 75270, Pakistan
| | | | | | | | | |
Collapse
|
11
|
de Oliveira Simões LC, da Silva RR, de Oliveira Nascimento CE, Boscolo M, Gomes E, da Silva R. Purification and Physicochemical Characterization of a Novel Thermostable Xylanase Secreted by the Fungus Myceliophthora heterothallica F.2.1.4. Appl Biochem Biotechnol 2019; 188:991-1008. [DOI: 10.1007/s12010-019-02973-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 02/01/2019] [Indexed: 01/13/2023]
|
12
|
Mhetras N, Mapre V, Gokhale D. Xylooligosaccharides (XOS) as Emerging Prebiotics: Its Production from Lignocellulosic Material. ACTA ACUST UNITED AC 2019. [DOI: 10.4236/aim.2019.91002] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
13
|
Sari B, Faiz O, Genc B, Sisecioglu M, Adiguzel A, Adiguzel G. New xylanolytic enzyme from Geobacillus galactosidasius BS61 from a geothermal resource in Turkey. Int J Biol Macromol 2018; 119:1017-1026. [DOI: 10.1016/j.ijbiomac.2018.07.166] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/24/2018] [Accepted: 07/25/2018] [Indexed: 11/28/2022]
|
14
|
Thermostable Xylanase Production by Geobacillus sp. Strain DUSELR13, and Its Application in Ethanol Production with Lignocellulosic Biomass. Microorganisms 2018; 6:microorganisms6030093. [PMID: 30189618 PMCID: PMC6164562 DOI: 10.3390/microorganisms6030093] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 08/29/2018] [Accepted: 08/31/2018] [Indexed: 01/11/2023] Open
Abstract
The aim of the current study was to optimize the production of xylanase, and its application for ethanol production using the lignocellulosic biomass. A highly thermostable crude xylanase was obtained from the Geobacillus sp. strain DUSELR13 isolated from the deep biosphere of Homestake gold mine, Lead, SD. Geobacillus sp. strain DUSELR13 produced 6 U/mL of the xylanase with the beechwood xylan. The xylanase production was improved following the optimization studies, with one factor at a time approach, from 6 U/mL to 19.8 U/mL with xylan. The statistical optimization with response surface methodology further increased the production to 31 U/mL. The characterization studies revealed that the crude xylanase complex had an optimum pH of 7.0, with a broad pH range of 5.0⁻9.0, and an optimum temperature of 75 °C. The ~45 kDa xylanase protein was highly thermostable with t1/2 of 48, 38, and 13 days at 50, 60, and 70 °C, respectively. The xylanase activity increased with the addition of Cu+2, Zn+2, K+, and Fe+2 at 1 mM concentration, and Ca+2, Zn+2, Mg+2, and Na⁺ at 10 mM concentration. The comparative analysis of the crude xylanase against its commercial counterpart Novozymes Cellic HTec and Dupont, Accellerase XY, showed that it performed better at higher temperature, hydrolyzing 65.4% of the beechwood at 75 °C. The DUSEL R13 showed the mettle to hydrolyze, and utilize the pretreated, and untreated lignocellulosic biomass: prairie cord grass (PCG), and corn stover (CS) as the substrate, and gave a maximum yield of 20.5 U/mL with the untreated PCG. When grown in co-culture with Geobacillus thermoglucosidasius, it produced 3.53 and 3.72 g/L ethanol, respectively with PCG, and CS. With these characteristics the xylanase under study could be an industrial success for the high temperature bioprocesses.
Collapse
|
15
|
Linares-Pastén JA, Aronsson A, Karlsson EN. Structural Considerations on the Use of Endo-Xylanases for the Production of prebiotic Xylooligosaccharides from Biomass. Curr Protein Pept Sci 2018; 19:48-67. [PMID: 27670134 PMCID: PMC5738707 DOI: 10.2174/1389203717666160923155209] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 08/31/2016] [Accepted: 09/15/2016] [Indexed: 11/24/2022]
Abstract
Xylooligosaccharides (XOS) have gained increased interest as prebiotics during the last years. XOS and arabinoxylooligosaccharides (AXOS) can be produced from major fractions of biomass including agricultural by-products and other low cost raw materials. Endo-xylanases are key enzymes for the production of (A)XOS from xylan. As the xylan structure is broadly diverse due to different substitutions, diverse endo-xylanases have evolved for its degradation. In this review structural and functional aspects are discussed, focusing on the potential applications of endo-xylanases in the production of differently substituted (A)XOS as emerging prebiotics, as well as their implication in the processing of the raw materials. Endo-xylanases are found in at least eight different glycoside hydrolase families (GH), and can either have a retaining or an inverting catalytic mechanism. To date, it is mainly retaining endo-xylanases that are used in applications to produce (A)XOS. Enzymes from these GH-families (mainly GH10 and GH11, and the more recently investigated GH30) are taken as prototypes to discuss substrate preferences and main products obtained. Finally, the need of new and accessory enzymes (new specificities from new families or sources) to increase the yield of different types of (A)XOS is discussed, along with in vitro tests of produced oligosaccharides and production of enzymes in GRAS organisms to facilitate use in functional food manufacturing.
Collapse
Affiliation(s)
| | - Anna Aronsson
- Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
| | | |
Collapse
|
16
|
Cordova LT, Cipolla RM, Swarup A, Long CP, Antoniewicz MR. 13C metabolic flux analysis of three divergent extremely thermophilic bacteria: Geobacillus sp. LC300, Thermus thermophilus HB8, and Rhodothermus marinus DSM 4252. Metab Eng 2017; 44:182-190. [PMID: 29037779 PMCID: PMC5845442 DOI: 10.1016/j.ymben.2017.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/09/2017] [Accepted: 10/11/2017] [Indexed: 01/26/2023]
Abstract
Thermophilic organisms are being increasingly investigated and applied in metabolic engineering and biotechnology. The distinct metabolic and physiological characteristics of thermophiles, including broad substrate range and high uptake rates, coupled with recent advances in genetic tool development, present unique opportunities for strain engineering. However, poor understanding of the cellular physiology and metabolism of thermophiles has limited the application of systems biology and metabolic engineering tools to these organisms. To address this concern, we applied high resolution 13C metabolic flux analysis to quantify fluxes for three divergent extremely thermophilic bacteria from separate phyla: Geobacillus sp. LC300, Thermus thermophilus HB8, and Rhodothermus marinus DSM 4252. We performed 18 parallel labeling experiments, using all singly labeled glucose tracers for each strain, reconstructed and validated metabolic network models, measured biomass composition, and quantified precise metabolic fluxes for each organism. In the process, we resolved many uncertainties regarding gaps in pathway reconstructions and elucidated how these organisms maintain redox balance and generate energy. Overall, we found that the metabolisms of the three thermophiles were highly distinct, suggesting that adaptation to growth at high temperatures did not favor any particular set of metabolic pathways. All three strains relied heavily on glycolysis and TCA cycle to generate key cellular precursors and cofactors. None of the investigated organisms utilized the Entner-Doudoroff pathway and only one strain had an active oxidative pentose phosphate pathway. Taken together, the results from this study provide a solid foundation for future model building and engineering efforts with these and related thermophiles.
Collapse
Affiliation(s)
- Lauren T Cordova
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Robert M Cipolla
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Adti Swarup
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Christopher P Long
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA.
| |
Collapse
|
17
|
Daas MJ, Martínez PM, van de Weijer AH, van der Oost J, de Vos WM, Kabel MA, van Kranenburg R. Biochemical characterization of the xylan hydrolysis profile of the extracellular endo-xylanase from Geobacillus thermodenitrificans T12. BMC Biotechnol 2017; 17:44. [PMID: 28521816 PMCID: PMC5437666 DOI: 10.1186/s12896-017-0357-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 03/25/2017] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Endo-xylanases are essential in degrading hemicellulose of various lignocellulosic substrates. Hemicellulose degradation by Geobacillus spp. is facilitated by the hemicellulose utilization (HUS) locus that is present in most strains belonging to this genus. As part of the HUS locus, the xynA gene encoding an extracellular endo-xylanase is one of the few secreted enzymes and considered to be the key enzyme to initiate hemicellulose degradation. Several Geobacillus endo-xylanases have been characterized for their optimum temperature, optimum pH and generation of degradation products. However, these analyses provide limited details on the mode of action of the enzymes towards various substrates resulting in a lack of understanding about their hydrolytic potential. RESULTS A HUS-locus associated gene (GtxynA1) from the thermophile Geobacillus thermodenitrificans T12 encodes an extracellular endo-xylanase that belongs to the family 10 glycoside hydrolases (GH10). The GtxynA1 gene was cloned and expressed in Escherichia coli. The resulting endo-xylanase (termed GtXynA1) was purified to homogeneity and showed activity between 40 °C and 80 °C, with an optimum activity at 60 °C, while being active between pH 3.0 to 9.0 with an optimum at pH 6.0. Its thermal stability was high and GtXynA1 showed 85% residual activity after 1 h of incubation at 60 °C. Highest activity was towards wheat arabinoxylan (WAX), beechwood xylan (BeWX) and birchwood xylan (BiWX). GtXynA1 is able to degrade WAX and BeWX producing mainly xylobiose and xylotriose. To determine its mode of action, we compared the hydrolysis products generated by GtXynA1 with those from the well-characterized GH10 endo-xylanase produced from Aspergillus awamori (AaXynA). The main difference in the mode of action between GtXynA1 and AaXynA on WAX is that GtXynA1 is less hindered by arabinosyl substituents and can therefore release shorter oligosaccharides. CONCLUSIONS The G. thermodenitrificans T12 endo-xylanase, GtXynA1, shows temperature tolerance up to 80 °C and high activity to a variety of xylans. The mode of action of GtXynA1 reveals that arabinose substituents do not hamper substrate degradation by GtXynA1. The extensive hydrolysis of branched xylans makes this enzyme particularly suited for the conversion of a broad range of lignocellulosic substrates.
Collapse
Affiliation(s)
- Martinus J.A. Daas
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, Wageningen, 6708 WE The Netherlands
| | - Patricia Murciano Martínez
- Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, Wageningen, 6708 WG The Netherlands
| | | | - John van der Oost
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, Wageningen, 6708 WE The Netherlands
| | - Willem M. de Vos
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, Wageningen, 6708 WE The Netherlands
| | - Mirjam A. Kabel
- Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, Wageningen, 6708 WG The Netherlands
| | - Richard van Kranenburg
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, Wageningen, 6708 WE The Netherlands
- Corbion, Arkelsedijk 46, Gorinchem, 4206 AC The Netherlands
| |
Collapse
|
18
|
de Sousa Gomes K, Maitan-Alfenas GP, de Andrade LGA, Falkoski DL, Guimarães VM, Alfenas AC, de Rezende ST. Purification and Characterization of Xylanases from the Fungus Chrysoporthe cubensis for Production of Xylooligosaccharides and Fermentable Sugars. Appl Biochem Biotechnol 2016; 182:818-830. [DOI: 10.1007/s12010-016-2364-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/07/2016] [Indexed: 11/24/2022]
|
19
|
Chakdar H, Kumar M, Pandiyan K, Singh A, Nanjappan K, Kashyap PL, Srivastava AK. Bacterial xylanases: biology to biotechnology. 3 Biotech 2016; 6:150. [PMID: 28330222 PMCID: PMC4929084 DOI: 10.1007/s13205-016-0457-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/10/2016] [Indexed: 12/04/2022] Open
Abstract
In this review, a comprehensive discussion exclusively on bacterial xylanases; their gene organization; different factors and conditions affecting enzyme yield and activity; and their commercial application have been deliberated in the light of recent research findings and extensive information mining. Improved understanding of biological properties and genetics of bacterial xylanase will enable exploitation of these enzymes for many more ingenious biotechnological and industrial applications.
Collapse
|
20
|
C-Terminal proline-rich sequence broadens the optimal temperature and pH ranges of recombinant xylanase from Geobacillus thermodenitrificans C5. Enzyme Microb Technol 2016; 91:34-41. [PMID: 27444327 DOI: 10.1016/j.enzmictec.2016.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 11/20/2022]
Abstract
Efficient utilization of hemicellulose entails high catalytic capacity containing xylanases. In this study, proline rich sequence was fused together with a C-terminal of xylanase gene from Geobacillus thermodenitrificans C5 and designated as GthC5ProXyl. Both GthC5Xyl and GthC5ProXyl were expressed in Escherichia coli BL21 host in order to determine effect of this modification. The C-terminal oligopeptide had noteworthy effects and instantaneously extended the optimal temperature and pH ranges and progressed the specific activity of GthC5Xyl. Compared with GthC5Xyl, GthC5ProXyl revealed improved specific activity, a higher temperature (70°C versus 60°C) and pH (8 versus 6) optimum, with broad ranges of temperature and pH (60-80°C and 6.0-9.0 versus 40-60°C and 5.0-8.0, respectively). The modified enzyme retained more than 80% activity after incubating in xylan for 3h at 80°C as compared to wild -type with only 45% residual activity. Our study demonstrated that proper introduction of proline residues on C-terminal surface of xylanase family might be very effective in improvement of enzyme thermostability. Moreover, this study reveals an engineering strategy to improve the catalytic performance of enzymes.
Collapse
|
21
|
Irfan M, Guler HI, Belduz AO, Shah AA, Canakci S. Cloning, purification and characterization of a cellulase-free xylanase from Geobacillus thermodenitrificans AK53. APPL BIOCHEM MICRO+ 2016. [DOI: 10.1134/s0003683816030066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
22
|
Cordova LT, Long CP, Venkataramanan KP, Antoniewicz MR. Complete genome sequence, metabolic model construction and phenotypic characterization of Geobacillus LC300, an extremely thermophilic, fast growing, xylose-utilizing bacterium. Metab Eng 2015; 32:74-81. [PMID: 26391740 DOI: 10.1016/j.ymben.2015.09.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 08/26/2015] [Accepted: 09/11/2015] [Indexed: 02/07/2023]
Abstract
We have isolated a new extremely thermophilic fast-growing Geobacillus strain that can efficiently utilize xylose, glucose, mannose and galactose for cell growth. When grown aerobically at 72 °C, Geobacillus LC300 has a growth rate of 2.15 h(-1) on glucose and 1.52 h(-1) on xylose (doubling time less than 30 min). The corresponding specific glucose and xylose utilization rates are 5.55 g/g/h and 5.24 g/g/h, respectively. As such, Geobacillus LC300 grows 3-times faster than E. coli on glucose and xylose, and has a specific xylose utilization rate that is 3-times higher than the best metabolically engineered organism to date. To gain more insight into the metabolism of Geobacillus LC300 its genome was sequenced using PacBio's RS II single-molecule real-time (SMRT) sequencing platform and annotated using the RAST server. Based on the genome annotation and the measured biomass composition a core metabolic network model was constructed. To further demonstrate the biotechnological potential of this organism, Geobacillus LC300 was grown to high cell-densities in a fed-batch culture, where cells maintained a high xylose utilization rate under low dissolved oxygen concentrations. All of these characteristics make Geobacillus LC300 an attractive host for future metabolic engineering and biotechnology applications.
Collapse
Affiliation(s)
- Lauren T Cordova
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA
| | - Christopher P Long
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA
| | - Keerthi P Venkataramanan
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA.
| |
Collapse
|
23
|
Bhalla A, Bischoff KM, Sani RK. Highly Thermostable Xylanase Production from A Thermophilic Geobacillus sp. Strain WSUCF1 Utilizing Lignocellulosic Biomass. Front Bioeng Biotechnol 2015; 3:84. [PMID: 26137456 PMCID: PMC4468944 DOI: 10.3389/fbioe.2015.00084] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/22/2015] [Indexed: 01/04/2023] Open
Abstract
Efficient enzymatic hydrolysis of lignocellulose to fermentable sugars requires a complete repertoire of biomass deconstruction enzymes. Hemicellulases play an important role in hydrolyzing hemicellulose component of lignocellulose to xylooligosaccharides and xylose. Thermostable xylanases have been a focus of attention as industrially important enzymes due to their long shelf life at high temperatures. Geobacillus sp. strain WSUCF1 produced thermostable xylanase activity (crude xylanase cocktail) when grown on xylan or various inexpensive untreated and pretreated lignocellulosic biomasses such as prairie cord grass and corn stover. The optimum pH and temperature for the crude xylanase cocktail were 6.5 and 70°C, respectively. The WSUCF1 crude xylanase was found to be highly thermostable with half-lives of 18 and 12 days at 60 and 70°C, respectively. At 70°C, rates of xylan hydrolysis were also found to be better with the WSUCF1 secretome than those with commercial enzymes, i.e., for WSUCF1 crude xylanase, Cellic-HTec2, and AccelleraseXY, the percent xylan conversions were 68.9, 49.4, and 28.92, respectively. To the best of our knowledge, WSUCF1 crude xylanase cocktail is among the most thermostable xylanases produced by thermophilic Geobacillus spp. and other thermophilic microbes (optimum growth temperature ≤70°C). High thermostability, activity over wide range of temperatures, and better xylan hydrolysis than commercial enzymes make WSUCF1 crude xylanase suitable for thermophilic lignocellulose bioconversion processes.
Collapse
Affiliation(s)
- Aditya Bhalla
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology , Rapid City, SD , USA
| | - Kenneth M Bischoff
- Renewable Product Technology Research Unit, Agricultural Research Service, National Center for Agricultural Utilization Research, U.S. Department of Agriculture , Peoria, IL , USA
| | - Rajesh Kumar Sani
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology , Rapid City, SD , USA
| |
Collapse
|
24
|
Bhalla A, Bischoff KM, Uppugundla N, Balan V, Sani RK. Novel thermostable endo-xylanase cloned and expressed from bacterium Geobacillus sp. WSUCF1. BIORESOURCE TECHNOLOGY 2014; 165:314-8. [PMID: 24725385 DOI: 10.1016/j.biortech.2014.03.112] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/19/2014] [Accepted: 03/21/2014] [Indexed: 05/16/2023]
Abstract
A gene encoding a GH10 endo-xylanase from Geobacillus sp. WSUCF1 was cloned and expressed in Escherichia coli. Recombinant endo-xylanase (37kDa) exhibited high specific activity of 461.0U/mg of protein. Endo-xylanase was optimally active on birchwood xylan at 70°C and pH 6.5. The endo-xylanase was found to be highly thermostable at 50 and 60°C, retaining 82% and 50% of its original activity, respectively, after 60h. High xylan conversions (92%) were obtained with oat-spelt xylan hydrolysis. Higher glucan and xylan conversions were obtained on AFEX-treated corn stover with an enzyme cocktail containing WSUCF1 endo-xylanase (71% and 47%) as compared to enzyme cocktail containing commercial fungal endo-xylanase (64% and 41%). High specific activity, active at high pH's, wide substrate specificity, and higher hydrolytic activity on recalcitrant lignocellulose, make this endo-xylanase a suitable candidate for biofuel and bioprocess industries.
Collapse
Affiliation(s)
- Aditya Bhalla
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA
| | - Kenneth M Bischoff
- Renewable Product Technology Research Unit, Agricultural Research Service, National Center for Agricultural Utilization Research, U.S. Department of Agriculture, Peoria, IL 61604, USA
| | - Nirmal Uppugundla
- Department of Chemical Engineering and Materials Science, DOE Great Lakes Bioenergy Research Center, Michigan State University, Lansing, MI 48823, USA
| | - Venkatesh Balan
- Department of Chemical Engineering and Materials Science, DOE Great Lakes Bioenergy Research Center, Michigan State University, Lansing, MI 48823, USA
| | - Rajesh K Sani
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA.
| |
Collapse
|