Promoting cellulase and hemicellulase production from Trichoderma orientalis EU7-22 by overexpression of transcription factors Xyr1 and Ace3.

The construction of hyper-production strains of cellulase is the prerequisite for the production of biofuels or biochemicals. Trichoderma orientalis EU7-22 with complete cellulase system shows the potential for cellulase production in industrial scale. To improve the cellulase production, two crucial transcription activators Xyr1 and Ace3 were constitutively overexpressed in EU7-22 strain. Cellulase, xylanase and protein secretion were significantly improved in the recombinant strain dxyA-8 under inducing culture, which were 2.34, 0.68 and 1.06 folds higher than those of EU7-22, respectively. Moreover, the FPase and CMCase activities were up to 2.55 IU/mL and 90.38 IU/mL with glucose as carbon source, which were 2.12 and 1.95 folds higher than those of EU7-22 under inducing condition, respectively. Reducing sugar released from pretreated spartina that hydrolyzed by crude enzyme from dxyA-8 had achieved 24% improvement. Therefore, overexpression of these transcription factors effectively promotes the production of cellulase and hemicellulase of Trichoderma orientalis EU7-22

Promoting cellulase and hemicellulase production from Trichoderma orientalis EU7-22 by overexpression of transcription factors Xyr1 and Ace3

Abstract(#br)The construction of hyper-production strains of cellulase is the prerequisite for the production of biofuels or biochemicals. Trichoderma orientalis EU7-22 with complete cellulase system shows the potential for cellulase production in industrial scale. To improve the cellulase production, two crucial transcription activators Xyr1 and Ace3 were constitutively overexpressed in EU7-22 strain. Cellulase, xylanase and protein secretion were significantly improved in the recombinant strain dxyA-8 under inducing culture, which were 2.34, 0.68 and 1.06 folds higher than those of EU7-22, respectively. Moreover, the FPase and CMCase activities were up to 2.55 IU/mL and 90.38 IU/mL with glucose as carbon source, which were 2.12 and 1.95 folds higher than those of EU7-22 under inducing condition, respectively. Reducing sugar released from pretreated spartina that hydrolyzed by crude enzyme from dxyA-8 had achieved 24% improvement. Therefore, overexpression of these transcription factors effectively promotes the production of cellulase and hemicellulase of Trichoderma orientalis EU7-22

An ultralight, supercompressible, superhydrophobic and multifunctional carbon aerogel with a specially designed structure

Abstract(#br)Compressible and ultralight carbon aerogels are attractive due to its compressibility, elasticity and conductivity. However, it is still a great challenge to enrich the properties of carbon aerogel to meet various requirements. Herein, we report an untralight, supercompressible, fatigue resistant, superhydrophobic and fire-resistant and multifunctional CNF-GO/glucose-kaolin carbon aerogel (C-NGGK) carbon aerogel. To achieve such excellent performances, calcined GO, CNFs, glucose and kaolin are used for forming low-density and continuous wave-shape rGO layers, reinforcing the mechanical strength of carbon layers, realizing superelasticity and fatigue resistance and resulting in a superhydrophobic surface for C-NGGK, respectively. The as-prepared C-NGGK demonstrates excellent superhydrophobicity with the water contact angle (WCA) of 124.9°, and the absorption efficiency of the C-NGGK samples for different oils and organic solvents are 75–255 times their own weight. These advantages show that the C-NGGK can be an ideal candidate for oil/water separation. In addition, there is also the prospect to be used for pressure sensors, while other potential applications include three-dimensional electrode materials for supercapacitors and batteries, catalyst carriers and various wearable devices

Variation of Yield and Composition of Energy Plant Erianthus arundinaceum During Different Growth Stages

研究不同时期斑茅产量及其化学组分的变化。结果表明:斑茅生物质产量在11月达到最高,其后开始下降;整个生长发育过程中茎叶生物质产量比呈现上升趋势;含水量随生长发育的进行显著降低;叶片灰分含量全年最低为5月,从10月份开始显著增加,至12月份达到最高。茎秆灰分含量略低于叶片,全年最低为10月,最高为7月,变化幅度不大。叶片中木质素含量全年由高到低排列顺序为12月>11月>9月>10月>7月>8月>6月;茎秆中木质素含量全年由高到低排列顺序为12月>11月>9月>7月>8月>10月>6月。10月份茎秆含水量低,灰分含量最低,热值较高,结合产量和燃料品质考虑其更适于直接燃烧,而9月份叶片则更加适于作为生物转化的材料。The effect of harvesting time on the yield and chemical composition of E.arundinaceum was studied.The results revealed that the highest biomass yield was available in November, and then the proportion of leaf biomass was gradually started to decline.The water content decreased significantly while the quantity of ash in leaves remained the lowest in May, which increased significantly in October and reached the highest amount in December.The quantity of ash in the stem was slightly lower than that in the leaf with little change year around.The maximum was appeared in July and the minimum was observed in October.The lignin content in the leaf was in the following downward order: Dec., Nov., Sept., Oct., July, Aug., June, and that for the stem was: Dec.,Nov., Sept., July., Aug., Oct., June.The calorific value of the leaf was the lowest in September and the highest in October, whereas that for the stem was the highest in August.The study showed that the best biomass accumulation was usually available with the lowest moisture and ash in October, which was more suitable for the production of fuel.The results proved that the lignin content of the leaf was lower than that of stem, which may be more suitable for bioconversion.国家自然科学基金(No.31170067;No.21303142); 福建省自然科学基金(No.2012J05029); 国家重点基础研究发展计划(973计划)(No.2010CB732201

Enhanced hydrogen production by insertional inactivation of adhE gene in Klebsiella oxytoca HP1

Ethanol is the main byproduct of anaerobic H-2-producing fermentation in Klebsiella oxytoca HP1. Two moles of NAD(P)H are consumed to yield one mole of ethanol that may decrease bacterial hydrogen production. In this article the adhE gene that codes for acetaldehyde dehydrogenase was disrupted for the first time. A homologous recombination vector pTA-Str was constructed in which the adhE gene was disrupted by inserting an aminoglycoside-3'-adenyltransferase (aadA) gene. As expected, the vector includes the insertion 5'-adhE-aadA-adhE-3'. The amplified DNA fragment 5'-adhE-aadA-adhE-31 from pTA-Str was transformed into K. oxytoca, HP1 and one recombinant was obtained. PCR analysis of the resulting genomic DNA indicated the appropriate deletion and insertion. Compared with the H-2-production of wild type K. oxytoca HP1, the hydrogen yield of the mutant increased by 16.07% and ethanol concentration decreased by 77.47%, suggesting that inactivation of the adhE gene in K. oxytoca HP1 is a potential method for enhancing bacterial H-2-production

Identification of a Genomic Region Containing a Novel Promoter Resistant to Glucose Repression and Over-Expression of β-Glucosidase Gene in Hypocrea orientalis EU7-22

Abstract: A high concentration of glucose in the medium could greatly inhibit the expression of cellulase in filamentous fungi. The aspartic protease from fungus Hypocrea orientalis EU7-22 could efficiently express under both induction condition and glucose repression condition. Based on the sequence of structure gene of aspartic protease, the upstream sequence harboring the putative promoter proA for driving the expression of aspartic protease was obtained by genome walking. The upstream sequence contained the typical promoter motifs “TATA ” and “CAAT”. The β-glucosidase gene (Bgl1) from H. orientalis was cloned and recombined with promoter proA and terminator trpC. The expression cassette was ligated to the binary vector to form pUR5750-Bgl1, and then transferred into the host strain EU7-22 via Agrobacterium tumefaciens mediated transformation (ATMT), using hygromycin B resistance gene as the screening marker

Improvement in xylooligosaccharides production by knockout of the beta-xyl1 gene in Trichoderma orientalis EU7-22

The goal of this study was to enhance the production of xylooligosaccharides (XOs) and reduce the production of xylose. We investigated beta-xylosidases, which were key enzymes in the hydrolysis of xylan into xylose, in Trichoderma orientalis EU7-22. The binary vector pUR5750G/bxl::hph was constructed to knock out the beta-xyl1 gene (encoding beta-xylosidases) in T. orientalis EU7-22 by homologous integration, producing the mutant strain T. orientalis Bxyl-1. Xylanase activity for strain Bxyl-1 was 452.42 IU/mL, which increased by only 0.07% compared to that of parental strain EU7-22, whereas beta-xylosidase activity was 0.06 IU/mL, representing a 91.89% decrease. When xylanase (200 IU/g xylan), produced by T. orientalis EU7-22 and T. orientalis Bxyl-1, was used to hydrolyze beechwood xylan, in contrast to the parental strain, the XOs were enhanced by 83.27%, whereas xylose decreased by 45.80% after 36 h in T. orientalis Bxyl-1. Based on these results, T. orientalis Bxyl-1 has great potential for application in the production of XOs from lignocellulosic biomass

Heterologous Expression of a New Acetyl Xylan Esterase from Aspergillus niger BE-2 and its Synergistic Action with Xylan-Degrading Enzymes in the Hydrolysis of Bamboo Biomass

Efficient utilization of plant biomass by enzymatic hydrolysis is currently studied worldwide but still faces enormous challenges because of the inability to break down lignocellulosic materials with high sugar yields and low enzyme dosage. Therefore, the synergistic action between various enzymes plays an important role in reaching this goal. The synergistic cooperation between a novel acetyl xylan esterase (heterologous expressed at high levels in this study) and four other xylan-degrading enzymes (reported previously) were performed in this study. The acetyl xylan esterase (AnAxe) gene was cloned from Aspergillus niger BE-2 and expressed in Pichia pastoris GS115. The deduced amino acid (aa) sequence consisted of 304-aa and included a 23-aa signal peptide and 281-aa mature protein. The AnAxe was extracellularly expressed with a molecular weight of ca. 31 kDa. The purified AnAxe exhibited maximal specific activity of 480.2 IU/mg at pH 7.0 and 40 C and was still thermostable below 50 C. The metal ions used in this study and EDTA showed a slight effect on the AnAxe. A significant synergistic effect was determined between AnAxe and the other four xylan-degrading enzymes, including endo--1,4-xylanases, -xylosidases, -L-arabinofurano-sidases, and -glucuronidases, on the degradation of bamboo biomass. The highest degree of synergism was obtained between AnAxe and endo--1,4-xylanases/-xylosidases

Comparative Analysis of Enzymatic Hydrolysis of Miscanthus Xylan using Aspergillus niger, Hypocrea orientalis, and Trichoderma reesei Xylan-degrading Enzymes

Xylan-degrading enzymes from Aspergillus niger and Hypocrea orientalis were characterized by enzyme activity assays and protein profiling with SDS-PAGE and LC-MS/MS. The hydrolysis of Miscanthus xylan by xylan-degrading enzymes from A. niger, H. orientalis, and Trichoderma reesei were comparatively studied by HPLC analysis. It was found that the glycoside hydrolase families 10 xylanase was the main xylanase secreted by H. orientalis and A. niger when using corn cob and wheat bran as inducers. Compared to the enzymes from T. reesei, the enzymes from A. niger showed better efficiency in the hydrolysis of Miscanthus xylan into monosaccharides. Nevertheless, the enzymes from H. orientalis were more preferable for the hydrolysis of Miscanthus xylan into xylo-oligosaccharides (XOS), especially xylobiose and xylotriose. Miscanthus xylan degradation was significantly influenced by the activities of β-xylosidase and α-L-arabinofuranosidase. Xylan-degrading enzymes with high ratios of β-xylosidase and α-L-arabinofuranosidase are necessary for the efficient conversion of Miscanthus xylan into monosaccharides. However, xylan-degrading enzymes with low β-xylosidase activity and high α-L-arabinofuranosidase activity were required for producing XOS