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Effect of Metabolic Structures and EnergyRequirements on Curdlan Production byAlcaligenes faecalis
Xiao Bei Zhan,Zhi-Yong Zheng,Jin Woo Lee,Zhongping Shi,Lei Wang,Li Zhu,Jian-Rong Wu,Chi Chung Lin 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.4
A comprehensive metabolic network was proposed for Alcaligenes faecalis and employed in a stoichiometrically based flux balance model for curdlan production optimization. The maximal yield of curdlan was evaluated for curdlan batch production. Various metabolic structures and metabolic pathway distributions related with the curdlan maximal yield was evaluated. The results showed that the energy efficiency rather than the substrate supply was the major constraint for the enhancement of curdlan production. The increase in specific rate of glucose uptake could enhance curdlan production yield due to the decrease of the ratio of metabolic maintenance to substrate consumption. However, some of the energy loss and nutrient limitation associated with the increase of metabolic maintenance would adversely affect the conversion efficiency of the substrate.
Jie Feng,Xiao-Bei Zhan,Dong Wang,Li-Min Zhang,Chi Chung Lin 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.2
Salt-tolerant aromatic yeast is an important microorganism arising from the solid state fermentation of soy sauce. The fermentation kinetics of volatile esters by Candida etchellsii was studied in a batch system. The data obtained from the fermentation were used for determining the kinetic parameters of the model. Batch experimental results at four NaCl levels (180, 200, 220, and 240 g/L) were used to formulate the parameter estimation model. The kinetic parameters of the model were optimized by specifically designed Runge-Kutta Genetic Algorithms (GA). The resulting mathematical model for volatile ester production, cell growth and glucose consumption simulates the experimental data well. The resulting new model was capable of explaining the behavior of volatile ester fermentation. The optimized parameters (μo, Xmax, Ki, α, β, YX/S, m, and YP/S) were characterized by a correlation of functions assuming salinity dependence. The kinetic models optimized by GA describe the batch fermentation process adequately, as demonstrated by our experimental results.
( Li Bo Yang ),( Xiao Meng Dai ),( Zhi Yong Zheng ),( Li Zhu ),( Xiao Bei Zhan ),( Chi Chung Lin ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.7
Osmotic pressure is a critical factor for erythritol production with osmophilic yeast. Protein expression patterns of an erythritol-producing yeast, Yarrowia lipolytica, were analyzed toidentify differentially-expressed proteins in response to osmotic pressure. In order to analyze intracellular protein levels quantitatively, two-dimensional gel electrophoresis was performed to separate and visualize the differential expression of the intracellular proteins extracted from Y. lipolytica cultured under low (3.17 osmol/kg) and high (4.21 osmol/kg) osmotic pressures. Proteomic analyses allowed identification of 54 differentially-expressed proteins among the proteins distributed in the range of pI 3-10 and 14.4-97.4 kDa molecular mass between the osmotic stress conditions. Remarkably, the main proteins were involved in the pathway of energy, metabolism, cell rescue, and stress response. The expression of such enzymes related to protein and nucleotide biosynthesis was inhibited drastically, reflecting the growth arrest of Y. lipolytica under hyperosmotic stress. The improvement of erythritol production under highosmotic stress was due to the significant induction of a range of crucial enzymes related to polyols biosynthesis, such as transketolase and triosephosphate isomerase, and the osmotic stress responsive proteins like pyridoxine-4-dehydrogenase and the AKRs family. The polyols biosynthesis was really related to an osmotic response and a protection mechanism against hyperosmotic stress in Y. lipolytica. Additionally, the high osmotic stress could also induce other cell stress responses as with heat shock and oxidation stress responses, and these responsive proteins, such as the HSPs family, catalase T, and superoxide dismutase, also had drastically increased expression levels under hyperosmotic pressure.
Jing Li,Li Zhu,Xiao-Bei Zhan,Min Xu,Chi Chung Lin,Zhiyong Zheng,Wei-Jiang Li 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.3
Endo-β-1,3-glucanase (Endo23) was purifiedfrom a Trichoderma reesei GIMCC 3.498 fermentationbroth using anion exchange and 2-stage size exclusionchromatography. Purification of 44.5× and a 12% recoveryyield of enzyme activity were achieved. The Mw andisoelectric point were estimated to be 24 kDa and 3.85using SDS-PAGE and IEF, respectively. The highestsubstrate specificity was observed for water-insoluble curdlan. The optimal conditions for hydrolyzing curdlan were pH5.0 and 50oC. The main hydrolytic products were glucobioseand glucotriose. Minor amounts of glucose and glucotetraosewere detected. Hg2+, Fe2+, Fe3+, and Sn2+ inhibited thehydrolysis activity of Endo23 at 5 and 50 mM. K+ slightlypromoted Endo23 activity. Endo23 belongs to the categoryEC3.2.1.39. The peptide sequences of Endo23 showedidentity with conserved sequences that typically exist in β-1,3-glucanases of the glycoside hydrolase family. TheEndo23 sequence was partially similar to a hypotheticallignocellulase from Penicillium oxalicum 114-2.
Effect of Metabolic Structures and Energy Requirements on Curdlan Production by Alcaligenes faecalis
Zheng, Zhi-Yong,Lee, Jin-Woo,Zhan, Xiao Bei,Shi, Zhongping,Wang, Lei,Zhu, Li,Wu, Jian-Rong,Lin, Chi Chung Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.4
A comprehensive metabolic network was proposed for Alcaligenes faecalis and employed in a stoichiometrically based flux balance model for curdlan production optimization. The maximal yield of curdlan was evaluated for curdlan batch production. Various metabolic structures and metabolic pathway distributions related with the curdlan maximal yield was evaluated. The results showed that the energy efficiency rather than the substrate supply was the major constraint for the enhancement of curdlan production. The increase in specific rate of glucose uptake could enhance curdlan production yield due to the decrease of the ratio of metabolic maintenance to substrate consumption. However, some of the energy loss and nutrient limitation associated with the increase of metabolic maintenance would adversely affect the conversion efficiency of the substrate.
Dong Wang,Zhiyong Zheng,Jie Feng,Xiao-Bei Zhan,Li-Min Zhang,Jian-Rong Wu,Chi-Chung Lin,Li Zhu 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.5
The temperature and pH stability of proteases have been extensively investigated. A neutral protease produced by Aspergillus oryzae was thermodynamically characterized at high-salt environment. When the protease was tested at 24% NaCl and 60oC, its half-life was increased to 30.0 min, 111% longer than that of control. Its Gibbs free energy and activation energy for denaturation in high NaCl concentration solutions were higher than in low salt solutions and increased by 2.1 and 4.75 kJ/mol,respectively. The protease exhibited higher thermal stability in higher salt conditions. This feature is beneficial to soybean sauce fermentation by enhancing the protease performance and taste of the product. Analysis by farultraviolet circular dichroism (far-UV CD) spectroscopy revealed that α-helix conformation in the protease increased from 3.2 to 31.7%, respectively, when the NaCl concentration increased from 0 to 18%, in agreement with the results deduced by thermodynamic calculations.
Jian-Rong Wu,Jin-Long Liu,Xiao-Bei Zhan,Chi-Chung Lin,Hui Zhao 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.4
Polysialic acid (PSA) is a capsular polysaccharide obtained from aerobic fermentation with Escherichia coli. To enhance PSA production and eliminate the influence of phosphate on the PSA purification process, a lower level of initial phosphate was adopted with pH control. The resulting PSA yield reached 4.1 g/L in fed-batch fermentation with 2.5 g/L K2HPO4 and E. coli strain CCTCC M208088. In addition, an ammonia water (NH4OH) feeding strategy to control the pH at 6.4 was developed resulting in PSA production that reached as high as 5.2 g/L. NMR spectra confirmed the purified biopolymer as a α-2,8linked PSA, identical to the published NMR spectra, with a molecular weight in the range of 16 ~ 50 kDa.