scholarly journals Chemical Pretreatment-Independent Saccharifications of Xylan and Cellulose of Rice Straw by Bacterial Weak Lignin-Binding Xylanolytic and Cellulolytic Enzymes

2017 ◽  
Vol 83 (22) ◽  
Author(s):  
Thitiporn Teeravivattanakit ◽  
Sirilak Baramee ◽  
Paripok Phitsuwan ◽  
Somphit Sornyotha ◽  
Rattiya Waeonukul ◽  
...  
Keyword(s):  
Lignocellulosic Biomass ◽  
Rice Straw ◽  
Chemical Pretreatment ◽  
Environment Friendly ◽  
Glucose Yield ◽  
Content Type ◽  
Enzyme Pretreatment ◽  
One Step ◽  
Arabinoxylan Arabinofuranohydrolase ◽  
Xylanolytic Enzyme

ABSTRACT Complete utilization of carbohydrate fractions is one of the prerequisites for obtaining economically favorable lignocellulosic biomass conversion. This study shows that xylan in untreated rice straw was saccharified to xylose in one step without chemical pretreatment, yielding 58.2% of the theoretically maximum value by Paenibacillus curdlanolyticus B-6 PcAxy43A, a weak lignin-binding trifunctional xylanolytic enzyme, endoxylanase/β-xylosidase/arabinoxylan arabinofuranohydrolase. Moreover, xylose yield from untreated rice straw was enhanced to 78.9% by adding endoxylanases PcXyn10C and PcXyn11A from the same bacterium, resulting in improvement of cellulose accessibility to cellulolytic enzyme. After autoclaving the xylanolytic enzyme-treated rice straw, it was subjected to subsequent saccharification by a combination of the Clostridium thermocellum endoglucanase CtCel9R and Thermoanaerobacter brockii β-glucosidase TbCglT, yielding 88.5% of the maximum glucose yield, which was higher than the glucose yield obtained from ammonia-treated rice straw saccharification (59.6%). Moreover, this work presents a new environment-friendly xylanolytic enzyme pretreatment for beneficial hydrolysis of xylan in various agricultural residues, such as rice straw and corn hull. It not only could improve cellulose saccharification but also produced xylose, leading to an improvement of the overall fermentable sugar yields without chemical pretreatment. IMPORTANCE Ongoing research is focused on improving “green” pretreatment technologies in order to reduce energy demands and environmental impact and to develop an economically feasible biorefinery. The present study showed that PcAxy43A, a weak lignin-binding trifunctional xylanolytic enzyme, endoxylanase/β-xylosidase/arabinoxylan arabinofuranohydrolase from P. curdlanolyticus B-6, was capable of conversion of xylan in lignocellulosic biomass such as untreated rice straw to xylose in one step without chemical pretreatment. It demonstrates efficient synergism with endoxylanases PcXyn10C and PcXyn11A to depolymerize xylan in untreated rice straw and enhanced the xylose production and improved cellulose hydrolysis. Therefore, it can be considered an enzymatic pretreatment. Furthermore, the studies here show that glucose yield released from steam- and xylanolytic enzyme-treated rice straw by the combination of CtCel9R and TbCglT was higher than the glucose yield obtained from ammonia-treated rice straw saccharification. This work presents a novel environment-friendly xylanolytic enzyme pretreatment not only as a green pretreatment but also as an economically feasible biorefinery method.

scholarly journals Novel Trifunctional Xylanolytic Enzyme Axy43A from Paenibacillus curdlanolyticus Strain B-6 Exhibiting Endo-Xylanase, β-d-Xylosidase, and Arabinoxylan Arabinofuranohydrolase Activities

2016 ◽  
Vol 82 (23) ◽  
pp. 6942-6951 ◽  
Author(s):  
Thitiporn Teeravivattanakit ◽  
Sirilak Baramee ◽  
Paripok Phitsuwan ◽  
Rattiya Waeonukul ◽  
Patthra Pason ◽  
...  
Keyword(s):  
Glycoside Hydrolase ◽  
Xylanase Activity ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Metabolic Potential ◽  
Gene Encoding ◽  
Content Type ◽  
Arabinoxylan Arabinofuranohydrolase ◽  
Paenibacillus Curdlanolyticus ◽  
Xylanolytic Enzyme

ABSTRACTTheaxy43Agene encoding the intracellular trifunctional xylanolytic enzyme fromPaenibacillus curdlanolyticusB-6 was cloned and expressed inEscherichia coli. Recombinant PcAxy43A consisting of a glycoside hydrolase family 43 and a family 6 carbohydrate-binding module exhibited endo-xylanase, β-xylosidase, and arabinoxylan arabinofuranohydrolase activities. PcAxy43A hydrolyzed xylohexaose and birch wood xylan to release a series of xylooligosaccharides, indicating that PcAxy43A contained endo-xylanase activity. PcAxy43A exhibited β-xylosidase activity toward a chromogenic substrate,p-nitrophenyl-β-d-xylopyranoside, and xylobiose, while it preferred to hydrolyze long-chain xylooligosaccharides rather than xylobiose. In addition, surprisingly, PcAxy43A showed arabinoxylan arabinofuranohydrolase activity; that is, it released arabinose from both singly and doubly arabinosylated xylose, α-l-Araf-(1→2)-d-Xylpor α-l-Araf-(1→3)-d-Xylpand α-l-Araf-(1→2)-[α-l-Araf-(1→3)]-β-d-Xylp. Moreover, the combination of PcAxy43A andP. curdlanolyticusB-6 endo-xylanase Xyn10C greatly improved the efficiency of xylose and arabinose production from the highly substituted rye arabinoxylan, suggesting that these two enzymes function synergistically to depolymerize arabinoxylan. Therefore, PcAxy43A has the potential for the saccharification of arabinoxylan into simple sugars for many applications.IMPORTANCEIn this study, the glycoside hydrolase 43 (GH43) intracellular multifunctional endo-xylanase, β-xylosidase, and arabinoxylan arabinofuranohydrolase (AXH) fromP. curdlanolyticusB-6 were characterized. Interestingly, PcAxy43A AXH showed a new property that acted on both the C(O)-2 and C(O)-3 positions of xylose residues doubly substituted with arabinosyl, which usually obstruct the action of xylanolytic enzymes. Furthermore, the studies here show interesting properties for the processing of xylans from cereal grains, particularly rye arabinoxylan, and show a novel relationship between PcAxy43A and endo-xylanase Xyn10C from strain B-6, providing novel metabolic potential for processing arabinoxylans into xylose and arabinose.

scholarly journals Squalene-Hopene Cyclases

2011 ◽  
Vol 77 (12) ◽  
pp. 3905-3915 ◽  
Author(s):  
Gabriele Siedenburg ◽  
Dieter Jendrossek
Keyword(s):  
Common Ancestor ◽  
Amino Acid Sequences ◽  
Enzymatic Reactions ◽  
Covalent Bonds ◽  
Content Type ◽  
Oxidosqualene Cyclase ◽  
Ring Structures ◽  
One Step ◽  
Alicyclobacillus Acidocaldarius ◽  
Eukaryotic Organisms

ABSTRACTHopanoids and sterols are members of a large group of cyclic triterpenoic compounds that have important functions in many prokaryotic and eukaryotic organisms. They are biochemically synthesized from linear precursors (squalene, 2,3-oxidosqualene) in only one enzymatic step that is catalyzed by squalene-hopene cyclase (SHC) or oxidosqualene cyclase (OSC). SHCs and OSCs are related in amino acid sequences and probably are derived from a common ancestor. The SHC reaction requires the formation of five ring structures, 13 covalent bonds, and nine stereo centers and therefore is one of the most complex one-step enzymatic reactions. We summarize the knowledge of the properties of triterpene cyclases and details of the reaction mechanism ofAlicyclobacillus acidocaldariusSHC. Properties of other SHCs are included.

scholarly journals One-Step Multiplex PCR Assay for Differentiating Proposed New Species “Clostridium neonatale” from Closely Related Species

2015 ◽  
Vol 53 (11) ◽  
pp. 3621-3623 ◽  
Author(s):  
Laurent Ferraris ◽  
Sophia Schönherr ◽  
Philippe Bouvet ◽  
Brunhilde Dauphin ◽  
Michel Popoff ◽  
...  
Keyword(s):  
New Species ◽  
Sensu Stricto ◽  
Preterm Neonates ◽  
Content Type ◽  
Colony Pcr ◽  
Multiplex Pcr Assay ◽  
Colonization Frequency ◽  
Content Identification ◽  
One Step ◽  
Neonatal Necrotizing Enterocolitis

“Clostridium neonatale” sp. nov., previously involved in an outbreak of neonatal necrotizing enterocolitis, was recently proposed as a new species of theClostridiumgenussensu stricto. We developed a one-step multiplex colony PCR forC. neonataleidentification and investigatedC. neonataleintestinal colonization frequency in healthy preterm neonates.

scholarly journals Microwave Assisted Chemical Pretreatment Method for Bio-ethanol Production from Rice Straw

2017 ◽  
Vol 29 (5) ◽  
pp. 943-950 ◽  
Author(s):  
Renu Singh ◽  
Monika Srivastava ◽  
Bharti Rohatgi ◽  
Abhijit Kar ◽  
Ashish Shukla
Keyword(s):  
Ethanol Production ◽  
Rice Straw ◽  
Chemical Pretreatment ◽  
Pretreatment Method ◽  
Microwave Assisted

scholarly journals A comprehensive study of the promoting effect of manganese on white rot fungal treatment for enzymatic hydrolysis of woody and grass lignocellulose

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Xiao Fu ◽  
Jialong Zhang ◽  
Xiangyu Gu ◽  
Hongbo Yu ◽  
Shulin Chen
Keyword(s):  
Wheat Straw ◽  
Lignocellulosic Biomass ◽  
Quantum Coherence ◽  
Plant Cell Wall ◽  
White Rot ◽  
Yield Enhancement ◽  
Biomass Recalcitrance ◽  
Fungal Treatment ◽  
Ether Linkage ◽  
Glucose Yield

Abstract Background The efficiency of biological systems as an option for pretreating lignocellulosic biomass has to be improved to make the process practical. Fungal treatment with manganese (Mn) addition for improving lignocellulosic biomass fractionation and enzyme accessibility were investigated in this study. The broad-spectrum effect was tested on two different types of feedstocks with three fungal species. Since the physicochemical and structural properties of biomass were the main changes caused by fungal degradation, detailed characterization of biomass structural features was conducted to understand the mechanism of Mn-enhanced biomass saccharification. Results The glucose yields of fungal-treated poplar and wheat straw increased by 2.97- and 5.71-fold, respectively, after Mn addition. Particularly, over 90% of glucose yield was achieved in Mn-assisted Pleurotus ostreatus-treated wheat straw. A comparison study using pyrolysis gas chromatography mass spectrometry (Py-GC/MS) and two-dimensional 1H–13C heteronuclear single quantum coherence (2D HSQC) nuclear magnetic resonance (NMR) spectroscopy was conducted to elucidate the role of Mn addition on fungal disruption of the cross-linked structure of whole plant cell wall. The increased Cα-oxidized products was consistent with the enhanced cleavage of the major β-O-4 ether linkages in poplar and wheat straw lignin or in the wheat straw lignin–carbohydrate complexes (LCCs), which led to the reduced condensation degree in lignin and decreased lignin content in Mn-assisted fungal-treated biomass. The correlation analysis and principal component analysis (PCA) further demonstrated that Mn addition to fungal treatment enhanced bond cleavage in lignin, especially the β-O-4 ether linkage cleavage played the dominant role in removing the biomass recalcitrance and contributing to the glucose yield enhancement. Meanwhile, enhanced deconstruction of LCCs was important in reducing wheat straw recalcitrance. The findings provided not only mechanistic insights into the Mn-enhanced biomass digestibility by fungus, but also a strategy for improving biological pretreatment efficiency of lignocellulose. Conclusion The mechanism of enhanced saccharification of biomass by Mn-assisted fungal treatment mainly through Cα-oxidative cleavage of β-O-4 ether linkages further led to the decreased condensation degree in lignin, as a result, biomass recalcitrance was significantly reduced by Mn addition. Graphic abstract

scholarly journals A novel high performance metagenome-derived alkali-thermostable endo-β-1,4-glucanase for lignocellulosic biomass hydrolysis in the harsh conditions

2020 ◽  
Author(s):  
Shohreh Ariaeenejad ◽  
Atefeh Sheykhabdolahzadeh ◽  
Morteza Maleki ◽  
Kaveh Kavousi ◽  
Mehdi Foroozandeh Shahraki ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Lignocellulosic Biomass ◽  
Rice Straw ◽  
Specific Activity ◽  
Agricultural Waste ◽  
Extreme Temperature ◽  
In Silico Analysis ◽  
Cellulose Content ◽  
Biomass Hydrolysis ◽  
Harsh Condition

Abstract Background: Lignocellulosic biomass, is a great resource for the production of bio-energy and bio-based material since it is largely abundant, inexpensive and renewable. The requirement of new energy sources has led to a wide search for novel effective enzymes to improve the exploitation of lignocellulose, among which the importance of thermostable and halotolerant cellulase enzymes with high pH performance is significant. Results: The primary aim of this study was to discover a novel alkali-thermostable endo-β-1,4-glucanase from the sheep rumen metagenome. Using a multi-step in-silico analysis, primary candidates with desired properties were found and subjected to cloning, expression, and purification followed by functional and structural characterization. The enzymes' kinetic parameters, including V max , Km, and specific activity, were calculated. The PersiCel4 demonstrated its optimum activity at pH 8.5 and a temperature of 85°C and was able to retain more than 70% of its activity after 150 hours of storage at 85°C. Furthermore, this enzyme was able to maintain its catalytic activity in the presence of different concentrations of NaCl, MgCl 2 , CaCl 2 , and MnCl 2 . Our results showed that treatment with MnCl 2 could enhance the enzyme’s activity by 89%. PersiCel4 was ultimately used for enzymatic hydrolysis of autoclave pretreated rice straw, the most abundant agricultural waste with rich cellulose content. In autoclave treated rice straw, enzymatic hydrolysis with the PersiCel4 increased the release of reducing sugar up to 260% after 72 hours in the harsh condition ( T= 85°C, pH = 8.5). Conclusion: Considering the urgent demand for stable cellulases that are operational on extreme temperature and pH conditions and due to several proposed distinctive characteristics of PersiCel4, it can be used in the harsh condition for bioconversion of lignocellulosic biomass.

Study on lignin-free lignocellulosic biomass and PSF-PEG membrane compatibility

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 1063-1075
Author(s):  
Abiodun A. Amusa ◽  
Abdul L. Ahmad ◽  
Jimoh K. Adewole
Keyword(s):  
Contact Angle ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Lignocellulosic Biomass ◽  
Biomedical Applications ◽  
Composite Membranes ◽  
Hydroxyl Groups ◽  
Chemical Pretreatment ◽  
Physical And Chemical ◽  
Porosity Measurements

Lignocellulosic biomass was delignified by combining physical and chemical pretreatment techniques. Then, a polysulfone-polyethylene glycol blend, which was compatible with the lignin-free biomass (0 wt% to 3.0 wt%), was used to fabricate composite membranes. The presence of hydroxyl groups after the pretreatment was evaluated via Fourier transform infrared spectroscopy. The rheology of the polymer solutions was assessed via the viscometric method. Also, the hydrophobicity of the fabricated membranes was determined using contact angle and porosity measurements. The fabricated membranes with near superhydrophobic properties (a contact angle of approximately 140°) based on this study revealed that contactor systems and biomedical applications would benefit from this modification.

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