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Papers by Ju Chu

Research paper thumbnail of Effect of medium and membrane permeability on the secretion of gentamicin

Through shake flask fermentation, the effects of pH, ratio of glucose and starch, trace elements,... more Through shake flask fermentation, the effects of pH, ratio of glucose and starch, trace elements, magnesium phosphate and surfactants on gentamicin biosynthesis and secretion were studied. Results show that improvement of the permeability of plasmic membrane could enhance the biosynthesis and secretion of gentamicin.

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Research paper thumbnail of Statistical Optimizing of Medium for Clavulanic Acid Production by Streptomyces clavuligerus Using Response Surface Methodology

Applied Biochemistry and Biotechnology, 2021

Clavulanic acid (CA) is a naturally occurring antibiotic produced by Streptomyces clavuligerus. S... more Clavulanic acid (CA) is a naturally occurring antibiotic produced by Streptomyces clavuligerus. Statistical optimization of the fermentation medium for CA production by Streptomyces clavuligerus was carried out. Multiple carbon sources, glycerol, dextrin, and triolein, were considered simultaneously. A two-level fractional factorial design experiment was conducted to identify the significant components of medium on CA production. Statistical analysis of the results showed that soybean meal, dextrin, and triolein were the most significant medium ingredients on CA production. The optimal level of these screened components was obtained by RSM based on the result of a Box-Behnken design, in which the values of dextrin, soybean meal, and triolein in CA fermentation medium were 12.37 g/L, 39.75 g/L, and 26.98 ml/L, respectively. Using the proposed optimized medium, the model predicted 938 mg/L of CA level and via experimental rechecking the model, 946 mg/L of CA level was attained in shake flask fermentation, significantly high than 630 mg/L of original medium. The optimized medium was further verified in 50-L stirred fermenter, and compared with performance of original medium in parallel, CA titer was increased from 889 to 1310 mg/L; a 47% increase was achieved through medium optimization by statistical approaches.

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Research paper thumbnail of Effect of biosurfactant sophorolipids on Rhizomucor miehei lipase fermentation by Aspergillus oryzae

Bioresources and Bioprocessing, 2021

In this study, the effect of biosurfactant sophorolipids (SLs) on Rhizomucor miehei lipase (RML) ... more In this study, the effect of biosurfactant sophorolipids (SLs) on Rhizomucor miehei lipase (RML) fermentation by Aspergillus oryzae was investigated. With the exogenous addition of 0.3% (w/v) SLs in the initial medium, the RML activity reached 430.0 U/mL, an increase of 25.0% compared to the control group. Subsequently, the physiological metabolic responses of A. oryzae to the addition of SLs were further explored. The results showed that though SLs had almost no effect on the RML secretion, it would affect the morphology of the cells. During the late phase of the fermentation, the proportion of middle pellets, which was generally considered as an energetic and stable state for enzyme production was increased with the addition of SLs. Simultaneously, the viscosity of fermentation broth was reduced, which facilitated the increase of oxygen transfer, thereby improving the RML production. Finally, it could be found that the addition of SLs significantly increased the contents of precur...

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Research paper thumbnail of Impact of Altered Trehalose Metabolism on Physiological Response of Penicillium chrysogenum Chemostat Cultures during Industrially Relevant Rapid Feast/Famine Conditions

Processes, 2021

Due to insufficient mass transfer and mixing issues, cells in the industrial-scale bioreactor are... more Due to insufficient mass transfer and mixing issues, cells in the industrial-scale bioreactor are often forced to experience glucose feast/famine cycles, mostly resulting in reduced commercial metrics (titer, yield and productivity). Trehalose cycling has been confirmed as a double-edged sword in the Penicillium chrysogenum strain, which facilitates the maintenance of a metabolically balanced state, but it consumes extra amounts of the ATP responsible for the repeated breakdown and formation of trehalose molecules in response to extracellular glucose perturbations. This loss of ATP would be in competition with the high ATP-demanding penicillin biosynthesis. In this work, the role of trehalose metabolism was further explored under industrially relevant conditions by cultivating a high-yielding Penicillium chrysogenum strain, and the derived trehalose-null strains in the glucose-limited chemostat system where the glucose feast/famine condition was imposed. This dynamic feast/famine re...

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Research paper thumbnail of Exploring the metabolic fate of propanol in industrial erythromycin-producing strain via 13C labeling experiments and enhancement of erythromycin production by rational metabolic engineering of Saccharopolyspora erythraea

Authorea

Propanol have been widely used as a precursor for erythromycin synthesis in industrial production... more Propanol have been widely used as a precursor for erythromycin synthesis in industrial production. However, the knowledge on the exact metabolic fate of propanol was still unclear. In the present study, the metabolic fate of propanol in industrial erythromycin-producing strain S. erythraea E3 was explored via 13C labeling experiments. An unexpected pathway in which propanol was channeled into tricarboxylic acid cycle was uncovered, resulting in uneconomic catabolism of propanol. By deleting the sucC gene, which encodes succinyl-CoA synthetase that catalyse a reaction in the unexpected propanol utilization pathway, a novel strain E3-ΔsucC was constructed. The strain E3-ΔsucC showed a significant enhancement in erythromycin production in the chemically defined medium compared to E3 (786.61 vs 392.94 mg/L). Isotopic dilution mass spectrometry metabolomics and isotopically nonstationary 13C metabolic flux analysis were employed to characterize the metabolic differences between S. erythraea E3 and E3-ΔsucC. The results showed that compared with the starting strain E3, the fluxes of pentose phosphate pathway in E3-△sucC increased by almost 200%. The most significant difference located in the tricarboxylic acid cycle was also found. The flux of the metabolic reaction catalyzed by succinyl-CoA synthetase in E3-ΔsucC was almost zero, while the glyoxylate bypass flux significantly increased. These new insights into the precursor utilization of antibiotic biosynthesis by rational metabolic engineering in S. erythraea provide the new vision in increasing industrial production of secondary metabolites.

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Research paper thumbnail of Coupled metabolic‐hydrodynamic modeling enabling rational scale‐up of industrial bioprocesses

Biotechnology and Bioengineering, 2019

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Research paper thumbnail of Optimized sampling protocol for mass spectrometry-based metabolomics in Streptomyces

Bioresources and Bioprocessing, 2019

In quantitative metabolomics studies, the most crucial step was arresting snapshots of all intere... more In quantitative metabolomics studies, the most crucial step was arresting snapshots of all interesting metabolites. However, the procedure customized for Streptomyces was so rare that most studies consulted the procedure from other bacteria even yeast, leading to inaccurate and unreliable metabolomics analysis. In this study, a base solution (acetone: ethanol = 1:1, mol/mol) was added to a quenching solution to keep the integrity of the cell membrane. Based on the molar transition energy (ET) of the organic solvents, five solutions were used to carry out the quenching procedures. These were acetone, isoamylol, propanol, methanol, and 60% (v/v) methanol. To the best of our knowledge, this is the first report which has utilized a quenching solution with ET values. Three procedures were also adopted for extraction. These were boiling, freezing–thawing, and grinding ethanol. Following the analysis of the mass balance, amino acids, organic acids, phosphate sugars, and sugar alcohols were...

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Research paper thumbnail of Screening endogenous signal peptides and protein folding factors to promote the secretory expression of heterologous proteins in Pichia pastoris

Journal of Biotechnology, 2019

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Research paper thumbnail of Efficient generation of male germ-like cells derived during co-culturing of adipose-derived mesenchymal stem cells with Sertoli cells under retinoic acid and testosterone induction

Stem Cell Research & Therapy, 2019

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Research paper thumbnail of Study on a two-component signal transduction system RimA1A2 that negatively regulates oxytetracycline biosynthesis in Streptomyces rimosus M4018

Bioresources and Bioprocessing, 2019

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Research paper thumbnail of Sustainable biosynthesis of curdlan from orange waste by using Alcaligenes faecalis: A systematically modeled approach

Carbohydrate Polymers, 2019

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Research paper thumbnail of Exploring cellular fatty acid composition and intracellular metabolites of osmotic-tolerant mutant Lactobacillus paracasei NCBIO-M2 for highly efficient lactic acid production with high initial glucose concentration

Journal of biotechnology, Jan 20, 2018

High titer, productivity and yield are the main pre-requisites of an efficient lactic acid produc... more High titer, productivity and yield are the main pre-requisites of an efficient lactic acid production process. However, the hyperosmotic stress inhibits cell metabolism in the later phase of fermentation. In this study, an osmotic-tolerant mutant named Lactobacillus paracasei NCBIO01-M2 was obtained through a high-throughput screening technology, which exhibited a higher tolerance to osmotic stress due to its more flexible regulation of the unsaturated fatty acid proportion along with the intracellular compatible solute pools. The mutant successfully consumed all 248 g/L initial glucose and produced 223.7 g/L lactic acid with a productivity of 5.53 g/L/h in a single batch fermentation by the neutralizing agent strategy. Moreover, similar fermentation performances were also achieved in the open fermentation mode without sterilization by the mutant, which suggested that the mutant would be a potential for cost-effective commercial lactic acid production.

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Research paper thumbnail of Kinetic analysis of sodium gluconate production by Aspergillus niger with different inlet oxygen concentrations

Bioprocess and biosystems engineering, 2018

To further understand fermentation kinetics of sodium gluconate (SG) production by Aspergillus ni... more To further understand fermentation kinetics of sodium gluconate (SG) production by Aspergillus niger with different inlet oxygen concentrations, logistic model for cell growth and two-step models for SG production and glucose consumption were established. The results demonstrated that the maximum specific growth rate (µ) presented exponential relationship with inlet oxygen concentration and the maximum biomass (X) exhibited linear increase. In terms of SG production, two-step model with Luedeking-Piret equation during growth phase and oxygen-dependent equation during stationary phase could well fit the experimental data. Notably, high inlet oxygen concentration exponentially improved SG yield (Y), whereas biomass yield to glucose (Y) and cell maintenance coefficient (m) were almost independent on inlet oxygen concentration, indicating that high oxygen supply enhancing SG synthesis not only functioning as a substrate directly, but also regulating glucose metabolism towards SG formati...

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Research paper thumbnail of Co-culture with TM4 cells enhances the proliferation and migration of rat adipose-derived mesenchymal stem cells with high stemness

Cytotechnology, Jan 21, 2018

The proliferation and migration of mesenchymal stem cells (MSCs) are the efficiency determinants ... more The proliferation and migration of mesenchymal stem cells (MSCs) are the efficiency determinants in MSCs transplant therapy. Sertoli cells considered as "nurse cell" possesses the ability to enhance the proliferation and migration of umbilical cord mesenchymal stem cells (UCMSCs). However, no reports about TM4 cells' effect on the proliferation and migration of adipose tissue-derived mesenchymal stem cells (ADSCs) have been found until at present research work. Therefore, this study investigates the effect of TM4 cells on the proliferation and migration of ADSCs. We found that the performance of proliferation and migration of ADSCs were improved significantly while maintaining their stemness and reducing their apoptosis rate. After co-culturing with TM4 cells, the co-cultured ADSCs demonstrated higher proportion of synthetic phase (S) cells and colony-forming units-fibroblastic (CFU-F) number, lower proportion of sub-G1 phase cells and enhanced osteogenic and adipogeni...

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Research paper thumbnail of Kinetic analysis of curdlan production by Alcaligenes faecalis with maltose, sucrose, glucose and fructose as carbon sources

Bioresource technology, 2018

Curdlan has wide-ranging benefits in food and pharmaceutical industries for its unique rheologica... more Curdlan has wide-ranging benefits in food and pharmaceutical industries for its unique rheological and thermal gelling properties. To analyze the cell growth and curdlan biosynthesis kinetics of Alcaligenes faecalis, the kinetic properties of the curdlan fermentation under different carbon sources conditions (maltose, sucrose, glucose and fructose) were investigated using Logistic and Luedeking-Piret equations. The results demonstrated that curdlan fermentation is partial growth-associated process. With maltose as the sole carbon source, the highest curdlan production (P = 39.3 g/L), the maximum specific growth rate (μ = 0.44/h) and the growth-associated rate constant (α = 2.05 g curdlan/g cell) were achieved. In contrast, the fructose was the less desired carbon source in both the cell growth and curdlan production. Further, the results demonstrated that slow-releasing glucose from maltose boosted cell growth and curdlan production.

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Research paper thumbnail of Comprehensive reconstruction and evaluation of Pichia pastoris genome-scale metabolic model that accounts for 1243 ORFs

Bioresources and Bioprocessing, 2017

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Research paper thumbnail of Metabolic flux analysis of the central carbon metabolism of the industrial vitamin B12 producing strain Pseudomonas denitrificans using 13C-labeled glucose

Journal of the Taiwan Institute of Chemical Engineers, 2012

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Research paper thumbnail of Accurate Determination of Isotopic Abundance of Intracellular Metabolites of Saccharopolysporaerythraea Based on Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry

Chinese Journal of Analytical Chemistry, 2017

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Research paper thumbnail of Enhancement of lipid productivity with a novel two-stage heterotrophic fed-batch culture of Chlorella protothecoides and a trial of CO 2 recycling by coupling with autotrophic process

Biomass and Bioenergy, 2016

Abstract In this study, the influences of oxygen supply and nitrogen starvation on cell growth an... more Abstract In this study, the influences of oxygen supply and nitrogen starvation on cell growth and lipid production by heterotrophic culture of Chlorella protothecoides were investigated in a 5-L stirred-tank bioreactor. The results demonstrated that both a low oxygen supply and nitrogen starvation are favorable for lipid accumulation, but limit cell growth and may therefore reduce the overall lipid production. Hence, a novel two-stage strategy for oxygen supply and nitrogen starvation was proposed in a batch culture, increasing the lipid content and yield on glucose by a factor 2.14 and 2.03 compared to the one-stage batch culture with high oxygen supply and sufficient nitrogen availability, respectively. Applying the two-stage process in a fed-batch culture further increased the lipid productivity to 175.2 mg/(L·h), giving a lipid yield of 195.6 mg/g. Furthermore, a dual-mode culture, coupling a heterotrophic process with autotrophic process, was implemented to allow for CO 2 recycling. This improved the lipid productivity and carbon utilization efficiency, further contributing towards cost-effective and environment-friendly algal lipid production.

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Research paper thumbnail of Power Input Effects on Degeneration in Prolonged Penicillin Chemostat Cultures: A Systems Analysis at Flux, Residual Glucose, Metabolite and Transcript Levels

Biotechnology and bioengineering, Jan 2, 2017

In the present work, by performing chemostat experiments at 400 and 600 RPM, two typical power in... more In the present work, by performing chemostat experiments at 400 and 600 RPM, two typical power inputs representative of industrial penicillin fermentation (P/V, 1.00 kW/m(3) in more remote zones and 3.83 kW/m(3) in the vicinity of the impellers, respectively) were scaled-down to bench-scale bioreactors. It was found that at 400 RPM applied in prolonged glucose-limited chemostat cultures, the previously reported degeneration of penicillin production using an industrial Penicillium chrysogenum strain was virtually absent. To investigate this, the cellular response was studied at flux (stoichiometry), residual glucose, intracellular metabolite and transcript levels. At 600 RPM, 20% more cell lysis was observed and the increased degeneration of penicillin production was accompanied by a 22% larger ATP gap and an unexpected 20-fold decrease in the residual glucose concentration (Cs, out ). At the same time, the biomass specific glucose consumption rate (qs ) did not change but the intrac...

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Research paper thumbnail of Effect of medium and membrane permeability on the secretion of gentamicin

Through shake flask fermentation, the effects of pH, ratio of glucose and starch, trace elements,... more Through shake flask fermentation, the effects of pH, ratio of glucose and starch, trace elements, magnesium phosphate and surfactants on gentamicin biosynthesis and secretion were studied. Results show that improvement of the permeability of plasmic membrane could enhance the biosynthesis and secretion of gentamicin.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Statistical Optimizing of Medium for Clavulanic Acid Production by Streptomyces clavuligerus Using Response Surface Methodology

Applied Biochemistry and Biotechnology, 2021

Clavulanic acid (CA) is a naturally occurring antibiotic produced by Streptomyces clavuligerus. S... more Clavulanic acid (CA) is a naturally occurring antibiotic produced by Streptomyces clavuligerus. Statistical optimization of the fermentation medium for CA production by Streptomyces clavuligerus was carried out. Multiple carbon sources, glycerol, dextrin, and triolein, were considered simultaneously. A two-level fractional factorial design experiment was conducted to identify the significant components of medium on CA production. Statistical analysis of the results showed that soybean meal, dextrin, and triolein were the most significant medium ingredients on CA production. The optimal level of these screened components was obtained by RSM based on the result of a Box-Behnken design, in which the values of dextrin, soybean meal, and triolein in CA fermentation medium were 12.37 g/L, 39.75 g/L, and 26.98 ml/L, respectively. Using the proposed optimized medium, the model predicted 938 mg/L of CA level and via experimental rechecking the model, 946 mg/L of CA level was attained in shake flask fermentation, significantly high than 630 mg/L of original medium. The optimized medium was further verified in 50-L stirred fermenter, and compared with performance of original medium in parallel, CA titer was increased from 889 to 1310 mg/L; a 47% increase was achieved through medium optimization by statistical approaches.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effect of biosurfactant sophorolipids on Rhizomucor miehei lipase fermentation by Aspergillus oryzae

Bioresources and Bioprocessing, 2021

In this study, the effect of biosurfactant sophorolipids (SLs) on Rhizomucor miehei lipase (RML) ... more In this study, the effect of biosurfactant sophorolipids (SLs) on Rhizomucor miehei lipase (RML) fermentation by Aspergillus oryzae was investigated. With the exogenous addition of 0.3% (w/v) SLs in the initial medium, the RML activity reached 430.0 U/mL, an increase of 25.0% compared to the control group. Subsequently, the physiological metabolic responses of A. oryzae to the addition of SLs were further explored. The results showed that though SLs had almost no effect on the RML secretion, it would affect the morphology of the cells. During the late phase of the fermentation, the proportion of middle pellets, which was generally considered as an energetic and stable state for enzyme production was increased with the addition of SLs. Simultaneously, the viscosity of fermentation broth was reduced, which facilitated the increase of oxygen transfer, thereby improving the RML production. Finally, it could be found that the addition of SLs significantly increased the contents of precur...

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Research paper thumbnail of Impact of Altered Trehalose Metabolism on Physiological Response of Penicillium chrysogenum Chemostat Cultures during Industrially Relevant Rapid Feast/Famine Conditions

Processes, 2021

Due to insufficient mass transfer and mixing issues, cells in the industrial-scale bioreactor are... more Due to insufficient mass transfer and mixing issues, cells in the industrial-scale bioreactor are often forced to experience glucose feast/famine cycles, mostly resulting in reduced commercial metrics (titer, yield and productivity). Trehalose cycling has been confirmed as a double-edged sword in the Penicillium chrysogenum strain, which facilitates the maintenance of a metabolically balanced state, but it consumes extra amounts of the ATP responsible for the repeated breakdown and formation of trehalose molecules in response to extracellular glucose perturbations. This loss of ATP would be in competition with the high ATP-demanding penicillin biosynthesis. In this work, the role of trehalose metabolism was further explored under industrially relevant conditions by cultivating a high-yielding Penicillium chrysogenum strain, and the derived trehalose-null strains in the glucose-limited chemostat system where the glucose feast/famine condition was imposed. This dynamic feast/famine re...

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Research paper thumbnail of Exploring the metabolic fate of propanol in industrial erythromycin-producing strain via 13C labeling experiments and enhancement of erythromycin production by rational metabolic engineering of Saccharopolyspora erythraea

Authorea

Propanol have been widely used as a precursor for erythromycin synthesis in industrial production... more Propanol have been widely used as a precursor for erythromycin synthesis in industrial production. However, the knowledge on the exact metabolic fate of propanol was still unclear. In the present study, the metabolic fate of propanol in industrial erythromycin-producing strain S. erythraea E3 was explored via 13C labeling experiments. An unexpected pathway in which propanol was channeled into tricarboxylic acid cycle was uncovered, resulting in uneconomic catabolism of propanol. By deleting the sucC gene, which encodes succinyl-CoA synthetase that catalyse a reaction in the unexpected propanol utilization pathway, a novel strain E3-ΔsucC was constructed. The strain E3-ΔsucC showed a significant enhancement in erythromycin production in the chemically defined medium compared to E3 (786.61 vs 392.94 mg/L). Isotopic dilution mass spectrometry metabolomics and isotopically nonstationary 13C metabolic flux analysis were employed to characterize the metabolic differences between S. erythraea E3 and E3-ΔsucC. The results showed that compared with the starting strain E3, the fluxes of pentose phosphate pathway in E3-△sucC increased by almost 200%. The most significant difference located in the tricarboxylic acid cycle was also found. The flux of the metabolic reaction catalyzed by succinyl-CoA synthetase in E3-ΔsucC was almost zero, while the glyoxylate bypass flux significantly increased. These new insights into the precursor utilization of antibiotic biosynthesis by rational metabolic engineering in S. erythraea provide the new vision in increasing industrial production of secondary metabolites.

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Research paper thumbnail of Coupled metabolic‐hydrodynamic modeling enabling rational scale‐up of industrial bioprocesses

Biotechnology and Bioengineering, 2019

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optimized sampling protocol for mass spectrometry-based metabolomics in Streptomyces

Bioresources and Bioprocessing, 2019

In quantitative metabolomics studies, the most crucial step was arresting snapshots of all intere... more In quantitative metabolomics studies, the most crucial step was arresting snapshots of all interesting metabolites. However, the procedure customized for Streptomyces was so rare that most studies consulted the procedure from other bacteria even yeast, leading to inaccurate and unreliable metabolomics analysis. In this study, a base solution (acetone: ethanol = 1:1, mol/mol) was added to a quenching solution to keep the integrity of the cell membrane. Based on the molar transition energy (ET) of the organic solvents, five solutions were used to carry out the quenching procedures. These were acetone, isoamylol, propanol, methanol, and 60% (v/v) methanol. To the best of our knowledge, this is the first report which has utilized a quenching solution with ET values. Three procedures were also adopted for extraction. These were boiling, freezing–thawing, and grinding ethanol. Following the analysis of the mass balance, amino acids, organic acids, phosphate sugars, and sugar alcohols were...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Screening endogenous signal peptides and protein folding factors to promote the secretory expression of heterologous proteins in Pichia pastoris

Journal of Biotechnology, 2019

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Research paper thumbnail of Efficient generation of male germ-like cells derived during co-culturing of adipose-derived mesenchymal stem cells with Sertoli cells under retinoic acid and testosterone induction

Stem Cell Research & Therapy, 2019

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Research paper thumbnail of Study on a two-component signal transduction system RimA1A2 that negatively regulates oxytetracycline biosynthesis in Streptomyces rimosus M4018

Bioresources and Bioprocessing, 2019

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Research paper thumbnail of Sustainable biosynthesis of curdlan from orange waste by using Alcaligenes faecalis: A systematically modeled approach

Carbohydrate Polymers, 2019

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Research paper thumbnail of Exploring cellular fatty acid composition and intracellular metabolites of osmotic-tolerant mutant Lactobacillus paracasei NCBIO-M2 for highly efficient lactic acid production with high initial glucose concentration

Journal of biotechnology, Jan 20, 2018

High titer, productivity and yield are the main pre-requisites of an efficient lactic acid produc... more High titer, productivity and yield are the main pre-requisites of an efficient lactic acid production process. However, the hyperosmotic stress inhibits cell metabolism in the later phase of fermentation. In this study, an osmotic-tolerant mutant named Lactobacillus paracasei NCBIO01-M2 was obtained through a high-throughput screening technology, which exhibited a higher tolerance to osmotic stress due to its more flexible regulation of the unsaturated fatty acid proportion along with the intracellular compatible solute pools. The mutant successfully consumed all 248 g/L initial glucose and produced 223.7 g/L lactic acid with a productivity of 5.53 g/L/h in a single batch fermentation by the neutralizing agent strategy. Moreover, similar fermentation performances were also achieved in the open fermentation mode without sterilization by the mutant, which suggested that the mutant would be a potential for cost-effective commercial lactic acid production.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Kinetic analysis of sodium gluconate production by Aspergillus niger with different inlet oxygen concentrations

Bioprocess and biosystems engineering, 2018

To further understand fermentation kinetics of sodium gluconate (SG) production by Aspergillus ni... more To further understand fermentation kinetics of sodium gluconate (SG) production by Aspergillus niger with different inlet oxygen concentrations, logistic model for cell growth and two-step models for SG production and glucose consumption were established. The results demonstrated that the maximum specific growth rate (µ) presented exponential relationship with inlet oxygen concentration and the maximum biomass (X) exhibited linear increase. In terms of SG production, two-step model with Luedeking-Piret equation during growth phase and oxygen-dependent equation during stationary phase could well fit the experimental data. Notably, high inlet oxygen concentration exponentially improved SG yield (Y), whereas biomass yield to glucose (Y) and cell maintenance coefficient (m) were almost independent on inlet oxygen concentration, indicating that high oxygen supply enhancing SG synthesis not only functioning as a substrate directly, but also regulating glucose metabolism towards SG formati...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Co-culture with TM4 cells enhances the proliferation and migration of rat adipose-derived mesenchymal stem cells with high stemness

Cytotechnology, Jan 21, 2018

The proliferation and migration of mesenchymal stem cells (MSCs) are the efficiency determinants ... more The proliferation and migration of mesenchymal stem cells (MSCs) are the efficiency determinants in MSCs transplant therapy. Sertoli cells considered as "nurse cell" possesses the ability to enhance the proliferation and migration of umbilical cord mesenchymal stem cells (UCMSCs). However, no reports about TM4 cells' effect on the proliferation and migration of adipose tissue-derived mesenchymal stem cells (ADSCs) have been found until at present research work. Therefore, this study investigates the effect of TM4 cells on the proliferation and migration of ADSCs. We found that the performance of proliferation and migration of ADSCs were improved significantly while maintaining their stemness and reducing their apoptosis rate. After co-culturing with TM4 cells, the co-cultured ADSCs demonstrated higher proportion of synthetic phase (S) cells and colony-forming units-fibroblastic (CFU-F) number, lower proportion of sub-G1 phase cells and enhanced osteogenic and adipogeni...

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Research paper thumbnail of Kinetic analysis of curdlan production by Alcaligenes faecalis with maltose, sucrose, glucose and fructose as carbon sources

Bioresource technology, 2018

Curdlan has wide-ranging benefits in food and pharmaceutical industries for its unique rheologica... more Curdlan has wide-ranging benefits in food and pharmaceutical industries for its unique rheological and thermal gelling properties. To analyze the cell growth and curdlan biosynthesis kinetics of Alcaligenes faecalis, the kinetic properties of the curdlan fermentation under different carbon sources conditions (maltose, sucrose, glucose and fructose) were investigated using Logistic and Luedeking-Piret equations. The results demonstrated that curdlan fermentation is partial growth-associated process. With maltose as the sole carbon source, the highest curdlan production (P = 39.3 g/L), the maximum specific growth rate (μ = 0.44/h) and the growth-associated rate constant (α = 2.05 g curdlan/g cell) were achieved. In contrast, the fructose was the less desired carbon source in both the cell growth and curdlan production. Further, the results demonstrated that slow-releasing glucose from maltose boosted cell growth and curdlan production.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comprehensive reconstruction and evaluation of Pichia pastoris genome-scale metabolic model that accounts for 1243 ORFs

Bioresources and Bioprocessing, 2017

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Research paper thumbnail of Metabolic flux analysis of the central carbon metabolism of the industrial vitamin B12 producing strain Pseudomonas denitrificans using 13C-labeled glucose

Journal of the Taiwan Institute of Chemical Engineers, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Accurate Determination of Isotopic Abundance of Intracellular Metabolites of Saccharopolysporaerythraea Based on Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry

Chinese Journal of Analytical Chemistry, 2017

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Research paper thumbnail of Enhancement of lipid productivity with a novel two-stage heterotrophic fed-batch culture of Chlorella protothecoides and a trial of CO 2 recycling by coupling with autotrophic process

Biomass and Bioenergy, 2016

Abstract In this study, the influences of oxygen supply and nitrogen starvation on cell growth an... more Abstract In this study, the influences of oxygen supply and nitrogen starvation on cell growth and lipid production by heterotrophic culture of Chlorella protothecoides were investigated in a 5-L stirred-tank bioreactor. The results demonstrated that both a low oxygen supply and nitrogen starvation are favorable for lipid accumulation, but limit cell growth and may therefore reduce the overall lipid production. Hence, a novel two-stage strategy for oxygen supply and nitrogen starvation was proposed in a batch culture, increasing the lipid content and yield on glucose by a factor 2.14 and 2.03 compared to the one-stage batch culture with high oxygen supply and sufficient nitrogen availability, respectively. Applying the two-stage process in a fed-batch culture further increased the lipid productivity to 175.2 mg/(L·h), giving a lipid yield of 195.6 mg/g. Furthermore, a dual-mode culture, coupling a heterotrophic process with autotrophic process, was implemented to allow for CO 2 recycling. This improved the lipid productivity and carbon utilization efficiency, further contributing towards cost-effective and environment-friendly algal lipid production.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Power Input Effects on Degeneration in Prolonged Penicillin Chemostat Cultures: A Systems Analysis at Flux, Residual Glucose, Metabolite and Transcript Levels

Biotechnology and bioengineering, Jan 2, 2017

In the present work, by performing chemostat experiments at 400 and 600 RPM, two typical power in... more In the present work, by performing chemostat experiments at 400 and 600 RPM, two typical power inputs representative of industrial penicillin fermentation (P/V, 1.00 kW/m(3) in more remote zones and 3.83 kW/m(3) in the vicinity of the impellers, respectively) were scaled-down to bench-scale bioreactors. It was found that at 400 RPM applied in prolonged glucose-limited chemostat cultures, the previously reported degeneration of penicillin production using an industrial Penicillium chrysogenum strain was virtually absent. To investigate this, the cellular response was studied at flux (stoichiometry), residual glucose, intracellular metabolite and transcript levels. At 600 RPM, 20% more cell lysis was observed and the increased degeneration of penicillin production was accompanied by a 22% larger ATP gap and an unexpected 20-fold decrease in the residual glucose concentration (Cs, out ). At the same time, the biomass specific glucose consumption rate (qs ) did not change but the intrac...

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