The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Cheng Zhong - One of the best experts on this subject based on the ideXlab platform.
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complete genome analysis of Gluconacetobacter xylinus cgmcc 2955 for elucidating bacterial cellulose biosynthesis and metabolic regulation
Scientific Reports, 2018Co-Authors: Miao Liu, Shiru Jia, Lingpu Liu, Yang Zou, Cheng ZhongAbstract:Complete genome sequence of Gluconacetobacter xylinus CGMCC 2955 for fine control of bacterial cellulose (BC) synthesis is presented here. The genome, at 3,563,314 bp, was found to contain 3,193 predicted genes without gaps. There are four BC synthase operons (bcs), among which only bcsI is structurally complete, comprising bcsA, bcsB, bcsC, and bcsD. Genes encoding key enzymes in glycolytic, pentose phosphate, and BC biosynthetic pathways and in the tricarboxylic acid cycle were identified. G. xylinus CGMCC 2955 has a complete glycolytic pathway because sequence data analysis revealed that this strain possesses a phosphofructokinase (pfk)-encoding gene, which is absent in most BC-producing strains. Furthermore, combined with our previous results, the data on metabolism of various carbon sources (monosaccharide, ethanol, and acetate) and their regulatory mechanism of action on BC production were explained. Regulation of BC synthase (Bcs) is another effective method for precise control of BC biosynthesis, and cyclic diguanylate (c-di-GMP) is the key activator of BcsA–BcsB subunit of Bcs. The quorum sensing (QS) system was found to positively regulate phosphodiesterase, which decomposed c-di-GMP. Thus, in this study, we demonstrated the presence of QS in G. xylinus CGMCC 2955 and proposed a possible regulatory mechanism of QS action on BC production.
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enhanced bacterial cellulose production by Gluconacetobacter xylinus via expression of vitreoscilla hemoglobin and oxygen tension regulation
Applied Microbiology and Biotechnology, 2018Co-Authors: Miao Liu, Shiru Jia, Yang Zou, Yongzhen Xie, Ying Hou, Cheng ZhongAbstract:Oxygen plays a key role during bacterial cellulose (BC) biosynthesis by Gluconacetobacter xylinus. In this study, the Vitreoscilla hemoglobin (VHb)-encoding gene vgb, which has been widely applied to improve cell survival during hypoxia, was heterologously expressed in G. xylinus via the pBla-VHb-122 plasmid. G. xylinus and G. xylinus-vgb + were statically cultured under hypoxic (10 and 15% oxygen tension in the gaseous phase), atmospheric (21%), and oxygen-enriched conditions (40 and 80%) to investigate the effect of oxygen on cell growth and BC production. Irrespective of vgb expression, we found that cell density increased with oxygen tension (10–80%) during the exponential growth phase but plateaued to the same value in the stationary phase. In contrast, BC production was found to significantly increase at lower oxygen tensions. In addition, we found that BC production at oxygen tensions of 10 and 15% was 26.5 and 58.6% higher, respectively, in G. xylinus-vgb + than that in G. xylinus. The maximum BC yield and glucose conversion rate, of 4.3 g/L and 184.7 mg/g, respectively, were observed in G. xylinus-vgb + at an oxygen tension of 15%. Finally, BC characterization suggested that hypoxic conditions enhance BC’s mass density, Young’s modulus, and thermostability, with G. xylinus-vgb + synthesizing softer BC than G. xylinus under hypoxia as a result of a decreased Young’s modulus. These results will facilitate the use of static culture for the production of BC.
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metabolic investigation in Gluconacetobacter xylinus and its bacterial cellulose production under a direct current electric field
Frontiers in Microbiology, 2016Co-Authors: Miao Liu, Cheng Zhong, Yuming Zhang, Chang Sheng Qiao, Shiru JiaAbstract:The effects of a direct current (DC) electric field on the growth and metabolism of Gluconacetobacter xylinus were investigated in static culture. When a DC electric field at 10 mA was applied using platinum electrodes to the culture broth, bacterial cellulose (BC) production was promoted in 12 hours (h) but was inhibited in the last 12 h as compared to the control (without DC electric field). At the cathode, the presence of the hydrogen generated a strong reductive environment that is beneficial to cell growth. As compared to the control, the activities of glycolysis and tricarboxylic acid cycle, as well as BC productivity were observed to be slightly higher in the first 12 h. However, due to the absence of sufficient oxygen, lactic acid was accumulated from pyruvic acid at 18 h, which was not in favor of BC production. At the anode, DC inhibited cell growth in 6 h when compared to the control. The metabolic activity in G. xylinus was inhibited through the suppression of the tricarboxylic acid cycle and glycolysis. At 18-24 h, cell density was observed to decrease, which might be due to the electrolysis of water that significantly dropped the pH of cultural broth far beyond the optimal range. Meanwhile, metabolites for self-protection were accumulated, for instance proline, glutamic acid, gluconic acid and fatty acids. Notably, the accumulation of gluconic acid and lactic acid made it a really tough acid stress to cells at the anode and finally led to depression of cell growth.
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metabolomic profiling coupled with metabolic network reveals differences in Gluconacetobacter xylinus from static and agitated cultures
Biochemical Engineering Journal, 2015Co-Authors: Miao Liu, Cheng Zhong, Yuqiao Wei, Peipei Han, Shiru JiaAbstract:Abstract Both static and agitated culture methods have their own disadvantages on producing bacterial cellulose (BC). To reveal the metabolic differences between these two culture methods, the intracellular metabolic profile characterization of Gluconacetobacter xylinus was investigated using gas chromatography coupled with mass spectrometry. A total of 79 intracellular metabolites in G. xylinus were detected and quantified. Trehalose was mainly responsible for the discrimination among different cultural groups. Coupled with metabolic network, BC production was divided into two stages in agitated culture. At the first stage, glucose was more converted to gluconic acid at high rotational speeds, resulting in a low conversion rate of glucose to BC. At the second stage, gluconic acid acted as carbon source pool for BC synthesis under glucose-limited conditions. However, the accumulation of self-protection metabolites (trehalose, amino acids and gluconic acid) on the 2nd day at 280 rpm branches much carbon source from BC synthesis, resulting in the inhibition of BC synthesis. The highest conversion rate of glucose to BC was observed in static culture, attributing to the inhibition of Glucose-6-phosphate dehydrogenase and the accumulation of by-products. These might be the possible reasons that G. xylinus in static and agitated cultures gave distinct BC yields.
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revealing differences in metabolic flux distributions between a mutant strain and its parent strain Gluconacetobacter xylinus cgmcc 2955
PLOS ONE, 2014Co-Authors: Cheng Zhong, Miao Liu, Shiru Jia, Xiaoning Yang, Huixia Zhu, Yuanyuan Jia, Luciano PiergiovanniAbstract:A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.
Tetsuo Kondo - One of the best experts on this subject based on the ideXlab platform.
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a uniaxially oriented nanofibrous cellulose scaffold from pellicles produced by Gluconacetobacter xylinus in dissolved oxygen culture
Carbohydrate Polymers, 2016Co-Authors: Aya Nagashima, Tsubasa Tsuji, Tetsuo KondoAbstract:An aerobic, Gram-negative bacterium, Gluconacetobacter xylinus, was successfully employed to produce a stretchable cellulose nanofiber pellicle using dissolved oxygen in a conventional cultured medium. The obtained nanofibers were highly crystalline with the metastable cellulose Iα phase being apparently the dominant phase by more than 90%. The obtained pellicle could be stretched by up to 1.5 times to provide oriented crystalline nanofibrous films. Low heating of the nanofibrous film induced the transformation of the dominant cellulose Iα crystalline phase into the Iβ crystalline phase without a loss of crystallinity or the high Young's modulus. The film also exhibited unique and anisotropic viscoelastic and mechanical properties as well as superior thermal stability compared with conventional high-performance synthetic polymeric materials. In addition, when G. xylinus cells were transferred to the oriented surface after stretched, they started to synthesize cellulose ribbons that parallel the nanofiber orientation of the substrate. This function as a template was evidenced by direct video imaging of the motion of the bacteria. The application of a bacterial culture using dissolved oxygen in the medium offers the fabrication of novel anisotropic and nanofibrous scaffold of cellulose Iα.
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in vivo curdlan cellulose bionanocomposite synthesis by genetically modified Gluconacetobacter xylinus
Biomacromolecules, 2015Co-Authors: Ju Fang, Shin Kawano, Kenji Tajima, Tetsuo KondoAbstract:Bacterial cellulose pellicle produced by Gluconacetobacter xylinus (G. xylinus) is one of the best biobased materials having a unique supernetwork structure with remarkable physiochemical properties for a wide range of medical and tissue-engineering applications. It is still necessary to modify them to obtain materials suitable for biomedical use with satisfactory mechanical strength, biodegradability, and bioactivity. The aim of this research was to develop a gene-transformation route for the production of bacterial cellulose/Curdlan (β-1,3-glucan) nanocomposites by separate but simultaneous in vivo synthesis of cellulose and Curdlan. Modification of the cellulose-nanofiber-producing system of G. xylinus enabled Curdlan to be synthesized simultaneously with cellulose nanofibers in vivo, resulting in biopreparation of nanocomposites. The obtained Curdlan/cellulose composites were characterized, and their properties were compared with those of normal bacterial cellulose pellicles, indicating that Curdlan mixed with the cellulose nanofibers at the nanoscale without disruption of the nanofiber network structure in the pellicle.
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structure elucidation of uniformly 13c labeled bacterial celluloses from different Gluconacetobacter xylinus strains
Cellulose, 2010Co-Authors: Stephanie Hesseertelt, Thomas Heinze, Eiji Togawa, Tetsuo KondoAbstract:The morphological and supramolecular structures of native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769) were investigated. Samples had been statically cultivated in Hestrin-Schramm medium containing fully 13C-labeled β-d-glucose-U-13C6 as the sole source of carbon. The results are compared with structure data of bacterial celluloses with a natural 13C abundance of 1.1%. Non-enriched and 13C-labeled cellulose pellicles formed crystalline structures as revealed by cross-polarized/magic-angle spinning (CP/MAS) 13C{1H}-NMR and near infrared (NIR) FT-Raman spectroscopic measurements as well as wide-angle X-ray diffraction (WAXD) investigations. Atomic force microscopy (AFM) was applied for analyzing fiber morphologies and surface properties. For the first time, details about the manipulation of fiber widths and pellicle formation were shown for different bacterial strains of G. xylinus depending on the use of β-d-glucose-U-13C6 for the biosynthesis.
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spectral assignments and anisotropy data of cellulose i α 13c nmr chemical shift data of cellulose iα determined by inadequate and rai techniques applied to uniformly 13c labeled bacterial celluloses of different Gluconacetobacter xylinus strains
Magnetic Resonance in Chemistry, 2008Co-Authors: Stephanie Hesseertelt, Raiker Witter, Anne S. Ulrich, Tetsuo Kondo, Thomas HeinzeAbstract:Solid-state 13C-NMR spectroscopy was used to characterize native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769), which had been statically cultivated in Hestrin–Schramm (HS) medium containing fully 13C-labeled β-D-glucose-U-13C6 as the sole source of carbon. For both samples, the 13C-NMR chemical shifts were completely assigned for each 13C-labeled site of cellulose Iα with the aid of 2D refocused INADEQUATE NMR. To determine the principal chemical shift tensor components, a pulse sequence based on the recoupling of anisotropy information (RAI) was applied at 10 kHz MAS. The detailed 13C tensors of cellulose Iα from different bacterial celluloses are thus available now for the first time, and these results have been compared with previously published data of nonenriched material and with theoretical predictions. Copyright © 2008 John Wiley & Sons, Ltd.
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Spectral assignments and anisotropy data of cellulose I?α: 13C-NMR chemical shift data of cellulose Iα determined by INADEQUATE and RAI techniques applied to uniformly 13C-labeled bacterial celluloses of different Gluconacetobacter xylinus strains
Magnetic resonance in chemistry : MRC, 2008Co-Authors: Stephanie Hesse-ertelt, Raiker Witter, Anne S. Ulrich, Tetsuo Kondo, Thomas HeinzeAbstract:Solid-state (13)C-NMR spectroscopy was used to characterize native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769), which had been statically cultivated in Hestrin-Schramm (HS) medium containing fully (13)C-labeled beta-D-glucose-U-(13)C(6) as the sole source of carbon. For both samples, the (13)C-NMR chemical shifts were completely assigned for each (13)C-labeled site of cellulose I(alpha) with the aid of 2D refocused INADEQUATE NMR. To determine the principal chemical shift tensor components, a pulse sequence based on the recoupling of anisotropy information (RAI) was applied at 10 kHz MAS. The detailed (13)C tensors of cellulose I(alpha) from different bacterial celluloses are thus available now for the first time, and these results have been compared with previously published data of nonenriched material and with theoretical predictions.
Miao Liu - One of the best experts on this subject based on the ideXlab platform.
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complete genome analysis of Gluconacetobacter xylinus cgmcc 2955 for elucidating bacterial cellulose biosynthesis and metabolic regulation
Scientific Reports, 2018Co-Authors: Miao Liu, Shiru Jia, Lingpu Liu, Yang Zou, Cheng ZhongAbstract:Complete genome sequence of Gluconacetobacter xylinus CGMCC 2955 for fine control of bacterial cellulose (BC) synthesis is presented here. The genome, at 3,563,314 bp, was found to contain 3,193 predicted genes without gaps. There are four BC synthase operons (bcs), among which only bcsI is structurally complete, comprising bcsA, bcsB, bcsC, and bcsD. Genes encoding key enzymes in glycolytic, pentose phosphate, and BC biosynthetic pathways and in the tricarboxylic acid cycle were identified. G. xylinus CGMCC 2955 has a complete glycolytic pathway because sequence data analysis revealed that this strain possesses a phosphofructokinase (pfk)-encoding gene, which is absent in most BC-producing strains. Furthermore, combined with our previous results, the data on metabolism of various carbon sources (monosaccharide, ethanol, and acetate) and their regulatory mechanism of action on BC production were explained. Regulation of BC synthase (Bcs) is another effective method for precise control of BC biosynthesis, and cyclic diguanylate (c-di-GMP) is the key activator of BcsA–BcsB subunit of Bcs. The quorum sensing (QS) system was found to positively regulate phosphodiesterase, which decomposed c-di-GMP. Thus, in this study, we demonstrated the presence of QS in G. xylinus CGMCC 2955 and proposed a possible regulatory mechanism of QS action on BC production.
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enhanced bacterial cellulose production by Gluconacetobacter xylinus via expression of vitreoscilla hemoglobin and oxygen tension regulation
Applied Microbiology and Biotechnology, 2018Co-Authors: Miao Liu, Shiru Jia, Yang Zou, Yongzhen Xie, Ying Hou, Cheng ZhongAbstract:Oxygen plays a key role during bacterial cellulose (BC) biosynthesis by Gluconacetobacter xylinus. In this study, the Vitreoscilla hemoglobin (VHb)-encoding gene vgb, which has been widely applied to improve cell survival during hypoxia, was heterologously expressed in G. xylinus via the pBla-VHb-122 plasmid. G. xylinus and G. xylinus-vgb + were statically cultured under hypoxic (10 and 15% oxygen tension in the gaseous phase), atmospheric (21%), and oxygen-enriched conditions (40 and 80%) to investigate the effect of oxygen on cell growth and BC production. Irrespective of vgb expression, we found that cell density increased with oxygen tension (10–80%) during the exponential growth phase but plateaued to the same value in the stationary phase. In contrast, BC production was found to significantly increase at lower oxygen tensions. In addition, we found that BC production at oxygen tensions of 10 and 15% was 26.5 and 58.6% higher, respectively, in G. xylinus-vgb + than that in G. xylinus. The maximum BC yield and glucose conversion rate, of 4.3 g/L and 184.7 mg/g, respectively, were observed in G. xylinus-vgb + at an oxygen tension of 15%. Finally, BC characterization suggested that hypoxic conditions enhance BC’s mass density, Young’s modulus, and thermostability, with G. xylinus-vgb + synthesizing softer BC than G. xylinus under hypoxia as a result of a decreased Young’s modulus. These results will facilitate the use of static culture for the production of BC.
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metabolic investigation in Gluconacetobacter xylinus and its bacterial cellulose production under a direct current electric field
Frontiers in Microbiology, 2016Co-Authors: Miao Liu, Cheng Zhong, Yuming Zhang, Chang Sheng Qiao, Shiru JiaAbstract:The effects of a direct current (DC) electric field on the growth and metabolism of Gluconacetobacter xylinus were investigated in static culture. When a DC electric field at 10 mA was applied using platinum electrodes to the culture broth, bacterial cellulose (BC) production was promoted in 12 hours (h) but was inhibited in the last 12 h as compared to the control (without DC electric field). At the cathode, the presence of the hydrogen generated a strong reductive environment that is beneficial to cell growth. As compared to the control, the activities of glycolysis and tricarboxylic acid cycle, as well as BC productivity were observed to be slightly higher in the first 12 h. However, due to the absence of sufficient oxygen, lactic acid was accumulated from pyruvic acid at 18 h, which was not in favor of BC production. At the anode, DC inhibited cell growth in 6 h when compared to the control. The metabolic activity in G. xylinus was inhibited through the suppression of the tricarboxylic acid cycle and glycolysis. At 18-24 h, cell density was observed to decrease, which might be due to the electrolysis of water that significantly dropped the pH of cultural broth far beyond the optimal range. Meanwhile, metabolites for self-protection were accumulated, for instance proline, glutamic acid, gluconic acid and fatty acids. Notably, the accumulation of gluconic acid and lactic acid made it a really tough acid stress to cells at the anode and finally led to depression of cell growth.
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metabolomic profiling coupled with metabolic network reveals differences in Gluconacetobacter xylinus from static and agitated cultures
Biochemical Engineering Journal, 2015Co-Authors: Miao Liu, Cheng Zhong, Yuqiao Wei, Peipei Han, Shiru JiaAbstract:Abstract Both static and agitated culture methods have their own disadvantages on producing bacterial cellulose (BC). To reveal the metabolic differences between these two culture methods, the intracellular metabolic profile characterization of Gluconacetobacter xylinus was investigated using gas chromatography coupled with mass spectrometry. A total of 79 intracellular metabolites in G. xylinus were detected and quantified. Trehalose was mainly responsible for the discrimination among different cultural groups. Coupled with metabolic network, BC production was divided into two stages in agitated culture. At the first stage, glucose was more converted to gluconic acid at high rotational speeds, resulting in a low conversion rate of glucose to BC. At the second stage, gluconic acid acted as carbon source pool for BC synthesis under glucose-limited conditions. However, the accumulation of self-protection metabolites (trehalose, amino acids and gluconic acid) on the 2nd day at 280 rpm branches much carbon source from BC synthesis, resulting in the inhibition of BC synthesis. The highest conversion rate of glucose to BC was observed in static culture, attributing to the inhibition of Glucose-6-phosphate dehydrogenase and the accumulation of by-products. These might be the possible reasons that G. xylinus in static and agitated cultures gave distinct BC yields.
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revealing differences in metabolic flux distributions between a mutant strain and its parent strain Gluconacetobacter xylinus cgmcc 2955
PLOS ONE, 2014Co-Authors: Cheng Zhong, Miao Liu, Shiru Jia, Xiaoning Yang, Huixia Zhu, Yuanyuan Jia, Luciano PiergiovanniAbstract:A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.
Shiru Jia - One of the best experts on this subject based on the ideXlab platform.
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complete genome analysis of Gluconacetobacter xylinus cgmcc 2955 for elucidating bacterial cellulose biosynthesis and metabolic regulation
Scientific Reports, 2018Co-Authors: Miao Liu, Shiru Jia, Lingpu Liu, Yang Zou, Cheng ZhongAbstract:Complete genome sequence of Gluconacetobacter xylinus CGMCC 2955 for fine control of bacterial cellulose (BC) synthesis is presented here. The genome, at 3,563,314 bp, was found to contain 3,193 predicted genes without gaps. There are four BC synthase operons (bcs), among which only bcsI is structurally complete, comprising bcsA, bcsB, bcsC, and bcsD. Genes encoding key enzymes in glycolytic, pentose phosphate, and BC biosynthetic pathways and in the tricarboxylic acid cycle were identified. G. xylinus CGMCC 2955 has a complete glycolytic pathway because sequence data analysis revealed that this strain possesses a phosphofructokinase (pfk)-encoding gene, which is absent in most BC-producing strains. Furthermore, combined with our previous results, the data on metabolism of various carbon sources (monosaccharide, ethanol, and acetate) and their regulatory mechanism of action on BC production were explained. Regulation of BC synthase (Bcs) is another effective method for precise control of BC biosynthesis, and cyclic diguanylate (c-di-GMP) is the key activator of BcsA–BcsB subunit of Bcs. The quorum sensing (QS) system was found to positively regulate phosphodiesterase, which decomposed c-di-GMP. Thus, in this study, we demonstrated the presence of QS in G. xylinus CGMCC 2955 and proposed a possible regulatory mechanism of QS action on BC production.
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enhanced bacterial cellulose production by Gluconacetobacter xylinus via expression of vitreoscilla hemoglobin and oxygen tension regulation
Applied Microbiology and Biotechnology, 2018Co-Authors: Miao Liu, Shiru Jia, Yang Zou, Yongzhen Xie, Ying Hou, Cheng ZhongAbstract:Oxygen plays a key role during bacterial cellulose (BC) biosynthesis by Gluconacetobacter xylinus. In this study, the Vitreoscilla hemoglobin (VHb)-encoding gene vgb, which has been widely applied to improve cell survival during hypoxia, was heterologously expressed in G. xylinus via the pBla-VHb-122 plasmid. G. xylinus and G. xylinus-vgb + were statically cultured under hypoxic (10 and 15% oxygen tension in the gaseous phase), atmospheric (21%), and oxygen-enriched conditions (40 and 80%) to investigate the effect of oxygen on cell growth and BC production. Irrespective of vgb expression, we found that cell density increased with oxygen tension (10–80%) during the exponential growth phase but plateaued to the same value in the stationary phase. In contrast, BC production was found to significantly increase at lower oxygen tensions. In addition, we found that BC production at oxygen tensions of 10 and 15% was 26.5 and 58.6% higher, respectively, in G. xylinus-vgb + than that in G. xylinus. The maximum BC yield and glucose conversion rate, of 4.3 g/L and 184.7 mg/g, respectively, were observed in G. xylinus-vgb + at an oxygen tension of 15%. Finally, BC characterization suggested that hypoxic conditions enhance BC’s mass density, Young’s modulus, and thermostability, with G. xylinus-vgb + synthesizing softer BC than G. xylinus under hypoxia as a result of a decreased Young’s modulus. These results will facilitate the use of static culture for the production of BC.
-
metabolic investigation in Gluconacetobacter xylinus and its bacterial cellulose production under a direct current electric field
Frontiers in Microbiology, 2016Co-Authors: Miao Liu, Cheng Zhong, Yuming Zhang, Chang Sheng Qiao, Shiru JiaAbstract:The effects of a direct current (DC) electric field on the growth and metabolism of Gluconacetobacter xylinus were investigated in static culture. When a DC electric field at 10 mA was applied using platinum electrodes to the culture broth, bacterial cellulose (BC) production was promoted in 12 hours (h) but was inhibited in the last 12 h as compared to the control (without DC electric field). At the cathode, the presence of the hydrogen generated a strong reductive environment that is beneficial to cell growth. As compared to the control, the activities of glycolysis and tricarboxylic acid cycle, as well as BC productivity were observed to be slightly higher in the first 12 h. However, due to the absence of sufficient oxygen, lactic acid was accumulated from pyruvic acid at 18 h, which was not in favor of BC production. At the anode, DC inhibited cell growth in 6 h when compared to the control. The metabolic activity in G. xylinus was inhibited through the suppression of the tricarboxylic acid cycle and glycolysis. At 18-24 h, cell density was observed to decrease, which might be due to the electrolysis of water that significantly dropped the pH of cultural broth far beyond the optimal range. Meanwhile, metabolites for self-protection were accumulated, for instance proline, glutamic acid, gluconic acid and fatty acids. Notably, the accumulation of gluconic acid and lactic acid made it a really tough acid stress to cells at the anode and finally led to depression of cell growth.
-
metabolomic profiling coupled with metabolic network reveals differences in Gluconacetobacter xylinus from static and agitated cultures
Biochemical Engineering Journal, 2015Co-Authors: Miao Liu, Cheng Zhong, Yuqiao Wei, Peipei Han, Shiru JiaAbstract:Abstract Both static and agitated culture methods have their own disadvantages on producing bacterial cellulose (BC). To reveal the metabolic differences between these two culture methods, the intracellular metabolic profile characterization of Gluconacetobacter xylinus was investigated using gas chromatography coupled with mass spectrometry. A total of 79 intracellular metabolites in G. xylinus were detected and quantified. Trehalose was mainly responsible for the discrimination among different cultural groups. Coupled with metabolic network, BC production was divided into two stages in agitated culture. At the first stage, glucose was more converted to gluconic acid at high rotational speeds, resulting in a low conversion rate of glucose to BC. At the second stage, gluconic acid acted as carbon source pool for BC synthesis under glucose-limited conditions. However, the accumulation of self-protection metabolites (trehalose, amino acids and gluconic acid) on the 2nd day at 280 rpm branches much carbon source from BC synthesis, resulting in the inhibition of BC synthesis. The highest conversion rate of glucose to BC was observed in static culture, attributing to the inhibition of Glucose-6-phosphate dehydrogenase and the accumulation of by-products. These might be the possible reasons that G. xylinus in static and agitated cultures gave distinct BC yields.
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revealing differences in metabolic flux distributions between a mutant strain and its parent strain Gluconacetobacter xylinus cgmcc 2955
PLOS ONE, 2014Co-Authors: Cheng Zhong, Miao Liu, Shiru Jia, Xiaoning Yang, Huixia Zhu, Yuanyuan Jia, Luciano PiergiovanniAbstract:A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.
Thomas Heinze - One of the best experts on this subject based on the ideXlab platform.
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structure elucidation of uniformly 13c labeled bacterial celluloses from different Gluconacetobacter xylinus strains
Cellulose, 2010Co-Authors: Stephanie Hesseertelt, Thomas Heinze, Eiji Togawa, Tetsuo KondoAbstract:The morphological and supramolecular structures of native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769) were investigated. Samples had been statically cultivated in Hestrin-Schramm medium containing fully 13C-labeled β-d-glucose-U-13C6 as the sole source of carbon. The results are compared with structure data of bacterial celluloses with a natural 13C abundance of 1.1%. Non-enriched and 13C-labeled cellulose pellicles formed crystalline structures as revealed by cross-polarized/magic-angle spinning (CP/MAS) 13C{1H}-NMR and near infrared (NIR) FT-Raman spectroscopic measurements as well as wide-angle X-ray diffraction (WAXD) investigations. Atomic force microscopy (AFM) was applied for analyzing fiber morphologies and surface properties. For the first time, details about the manipulation of fiber widths and pellicle formation were shown for different bacterial strains of G. xylinus depending on the use of β-d-glucose-U-13C6 for the biosynthesis.
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spectral assignments and anisotropy data of cellulose i α 13c nmr chemical shift data of cellulose iα determined by inadequate and rai techniques applied to uniformly 13c labeled bacterial celluloses of different Gluconacetobacter xylinus strains
Magnetic Resonance in Chemistry, 2008Co-Authors: Stephanie Hesseertelt, Raiker Witter, Anne S. Ulrich, Tetsuo Kondo, Thomas HeinzeAbstract:Solid-state 13C-NMR spectroscopy was used to characterize native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769), which had been statically cultivated in Hestrin–Schramm (HS) medium containing fully 13C-labeled β-D-glucose-U-13C6 as the sole source of carbon. For both samples, the 13C-NMR chemical shifts were completely assigned for each 13C-labeled site of cellulose Iα with the aid of 2D refocused INADEQUATE NMR. To determine the principal chemical shift tensor components, a pulse sequence based on the recoupling of anisotropy information (RAI) was applied at 10 kHz MAS. The detailed 13C tensors of cellulose Iα from different bacterial celluloses are thus available now for the first time, and these results have been compared with previously published data of nonenriched material and with theoretical predictions. Copyright © 2008 John Wiley & Sons, Ltd.
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Spectral assignments and anisotropy data of cellulose I?α: 13C-NMR chemical shift data of cellulose Iα determined by INADEQUATE and RAI techniques applied to uniformly 13C-labeled bacterial celluloses of different Gluconacetobacter xylinus strains
Magnetic resonance in chemistry : MRC, 2008Co-Authors: Stephanie Hesse-ertelt, Raiker Witter, Anne S. Ulrich, Tetsuo Kondo, Thomas HeinzeAbstract:Solid-state (13)C-NMR spectroscopy was used to characterize native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769), which had been statically cultivated in Hestrin-Schramm (HS) medium containing fully (13)C-labeled beta-D-glucose-U-(13)C(6) as the sole source of carbon. For both samples, the (13)C-NMR chemical shifts were completely assigned for each (13)C-labeled site of cellulose I(alpha) with the aid of 2D refocused INADEQUATE NMR. To determine the principal chemical shift tensor components, a pulse sequence based on the recoupling of anisotropy information (RAI) was applied at 10 kHz MAS. The detailed (13)C tensors of cellulose I(alpha) from different bacterial celluloses are thus available now for the first time, and these results have been compared with previously published data of nonenriched material and with theoretical predictions.