Optimization of medium components for D-ribose production by transketolase-deficient Bacillus subtilis NJT-1507

Hanjie Ying,Ting Fang,Xiaochun Chen,Nan Li,He Song,Jianxin Bai,Jian Xiong 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6

Statistical experimental designs were used to optimize the composition of culture media for the production of D-ribose by Bacillus subtilis. A fractional factorial design 2(5-2) was used to determine medium components that significantly affected D-ribose production. The concentrations of glucose and (NH4)2SO4 were the significant factors. Central composite design and response surface methodology were then used to estimate the quadratic response surface and determine the factor levels for maximum production of D-ribose. Finally, the optimal medium composition was obtained (g/L): glucose, 172.75; (NH4) 2SO4, 13.2; yeast powder, 4; corn steep liquor, 8 and MnSO4, 0.5. This optimization strategy increased D-ribose production from 73.21 g/L to 88.57 g/L, an increase of 22% compared with the original conditions. The D-ribose production yield to glucose concentration was also enhanced from 0.37 g/g to 0.52 g/g. Confirmatory experiments were also performed to demonstrate the accuracy of the model. Under the optimal medium using ammonia to control pH in a 5 L fermenter, the D-ribose yield was increased to 95.28 g/L after 3 days of cultivation at 37 oC.

Production of cyclic adenosine-3',5'-monophosphate by whole cell catalysis using recombinant Escherichia coli overexpressing adenylate cyclase

Hanjie Ying,Jingjing Xie,Nan Li,Ying He,Yong Chen,Xiaochun Chen,Jianxin Bai,Jinglan Wu 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.4

Adenylate cyclase (EC 4.6.1.1) catalyzes the formation of cyclic adenosine-3',5'-monophosphate (cAMP)from adenosine 5'-triphosphate (ATP). Recombinant Escherichia coli overexpressing adenylate cyclase was used to synthesize cAMP by whole cell catalysis. Some key parameters were examined during the catalytic process, while pH and Mg2+ were found to influence cAMP production significantly. Optimum conditions were pH 8.52 and 30 oC with 77.2 mM Mg2+ in 100 mM Tris-HCl buffer, including 0.25% Triton-X 100 as detergent and 30 mM pyruvate sodium as enzyme activator for 6 h. 14.93 g/L of cAMP was produced with a conversion rate of 91.5%. The current work provided a potential way for the industrial production of cAMP.

Determination of optimal conditions for ribonucleic acid production by Candida tropicalis no. 121

Huajing Ren,Hanjie Ying,Xiaochun Chen,Jiaming Cao,Lei Li,Jianxin Bai,Yong Chen,Jian Xiong 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.8

The experiments were based on multivariate statistical concepts, and response surface methodology (RSM)was applied to optimize the fermentation medium for the production of ribonucleic acid (RNA) by Candida tropicalis no. 121. The process involved the individual adjustment and optimization of various medium components at shake flask level. The two-level Plackett-Burman (PB) design was used to screen the medium components, which significantly influenced RNA production. Among seven variables, the concentrations of molasses, ZnSO_4, and H_3PO_4 were found to be the important factors that significantly affected RNA production (confidence levels above 95%). These factors were further optimized using a central composite design (CCD) and RSM. The optimum values for the critical components were as follows: molasses 47.21 g/L: ZnSO_4 0.048 g/L; H_3PO_4 1.19 g/L. Under optimal conditions, RNA production was 2.56 g/L, which was in excellent agreement with the predicted value (2.561 g/L), and led to a 2.1-fold increase compare with that using the original medium in RNA production.

Mutation breeding of nuclease p1 production in Penicillium citrinum by low-energy ion beam implantation

Qinting He,Hanjie Ying,Nan Li,Xiaochun Chen,Qi Ye,Jianxin Bai,Jian Xiong 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2

Nuclease p1 is an important enzyme in the nucleotide industry that is used to hydrolyze nucleic acid into nucleotides. To improve enzyme activity, Penicillium citrinum, a nuclease p1 producing strain, was mutated by lowenergy Nitrogen ion beam implantation at an energy level of 15 keV and a dose ranging from 1×10^(15)-1×10^(16) ions/cm^2. The mutant strain designated as N409 was obtained with a high yield of nuclease p1. The activity of nuclease p1 was 421 U/mL from the mutant strain N409, which was increased by 86% compared with the control. The fermentation kinetics of nuclease p1 by the mutant strain N409 was studied in a 30 L external airlifting bioreactor. A model was proposed using the logistic equation for microbial growth, the Luedeking-Piret equation for product formation and a Luedeking-Piret-like equation for substrate uptake. The results predicted from the model were in good agreement with the experimental observations.

Enhanced adenosine triphosphate production by Saccharomyces cerevisiae using an efficient energy regeneration system

Yuelan Yao,Hanjie Ying,Jian Xiong,Yong Chen,Jiapeng Tang 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1

The process of ATP biosynthesis from adenosine catalyzed by Saccharomyces cerevisiae was studied using an efficient energy regeneration system. A fractional factorial design (2^(9-5)) was used to evaluate the effects of different components in the medium. Magnesium chloride, toluene, and acetaldehyde were found to significantly influence ATP production. The concentrations of the three factors were then optimized using central composition design and response surface analysis. Based on the second-order polynomial model obtained from the experiments, the optimal parameters were obtained as follows: adenosine 20 g/L; glucose 67 g/L; S. cerevisiae cells 250 g/L; magnesium chloride 4.37 g/L;potassium dihydrogen phosphate 67 g/L; toluene 1.40 mL/L; acetaldehyde 2.67 mL/L; pH 7.0; and temperature 37.0 ℃. Under the condition, the yield and concentration of ATP reached 97.5% and 37 g/L, respectively. The yield was nearly 10% higher than the level before optimization and the concentration increased two-fold. In addition, the utilization efficiency of energy after optimization increased nearly 6%.

Feasibility Study on Long-Term Continuous Ethanol Production from Cassava Supernatant by Immobilized Yeast Cells in Packed Bed Reactor

Liu Qingguo,Zhao Nan,Zou Yanan,Ying Hanjie,Dong Liu,Chen Yong 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.8

In this study, yeast cell immobilization was carried out in a packed bed reactor (PBR) to investigate the effects of the volumetric capacity of carriers as well as the different fermentation modes on fuel ethanol production. An optimal volumetric capacity of 10 g/l was found to obtain a high cell concentration. The productivity of immobilized cell fermentation was 16% higher than that of suspended-cell fermentation in batch and it reached a higher value of 4.28 g/l/h in repeated batches. Additionally, using this method, the ethanol yield (95.88%) was found to be higher than that of other tested methods due to low concentrations of residual sugars and free cells. Continuous ethanol production using four bioreactors showed a higher productivity (9.57 g/l/h) and yield (96.96%) with an ethanol concentration of 104.65 g/l obtained from 219.42 g/l of initial total sugar at a dilution rate of 0.092 h-1. Furthermore, we reversed the substrate-feed flow directions in the in-series bioreactors to keep the cells at their highest activity and to extend the length of continuous fermentation. Our study demonstrates an effective method of ethanol production with a new immobilized approach, and that by switching the flow directions, traditional continuous fermentation can be greatly improved, which could have practical and broad implications in industrial applications.

Strain Improvement and Metabolic Flux Modeling of Wild-type and Mutant Alcaligenes sp. NX-3 for Synthesis of Exopolysaccharide Welan Gum

Hui Li,Hong Xu,Sha Li,Hao Xu,Chaojiang Guo,Pingkai Ouyang,Hanjie Ying 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.5

Low-energy nitrogen ion beam implantation technique was used for the strain improvement of Alcaligenes sp. NX-3 for the production of exopolysaccharide welan gum. A high welan gum producing mutant, Alcaligenes sp. NX-3-1, was obtained through 20 keV N+ ion beam irradiation. Starting at a concentration of 50 g/L of glucose, mutant NX-3-1 produced 25.0 g/L of welan gum after 66 h of cultivation in a 7.5 L bioreactor, which was 34.4% higher than that produced by the wild-type strain. The results of metabolic flux analysis showed that the glucose-6-phosphate and acetyl coenzyme A nodes were the principle and flexible nodes, respectively. At the glucose-6-phosphate node, the fraction of carbon measured from glucose-6-phosphate to glucose-1-phosphate was enhanced after mutagenesis, which indicated that more flux was used to synthesize welan gum in the mutant. By analyzing the activities of related enzymes in the biosynthetic pathway of sugar nucleotides essential for welan gum production, we found that the specific activities of phosphoglucomutase, UDP-glucose pyrophosphorylase,UDP-glucose dehydrogenase, and dTDP-glucose pyrophosphorylase in the mutant strain were higher than those in the wild-type strain. These improvements in enzyme activities could be due to the affected of ion beam implantation.

D-Lactic Acid Production by Sporolactobacillus inulinus Y2-8 Immobilized in Fibrous Bed Bioreactor Using Corn Flour Hydrolyzate

( Ting Zhao ),( Dong Liu ),( Hengfei Ren ),( Xinchi Shi ),( Nan Zhao ),( Yong Chen ),( Hanjie Ying ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.12

In this study, a fibrous bed bioreactor (FBB) was used for D-lactic acid (D-LA) production by Sporolactobacillus inulinus Y2-8. Corn flour hydrolyzed with α-amylase and saccharifying enzyme was used as a cost-efficient and nutrient-rich substrate for D-LA production. A maximal starch conversion rate of 93.78% was obtained. The optimum pH for D-LA production was determined to be 6.5. Ammonia water was determined to be an ideal neutralizing agent, which improved the D-LA production and purification processes. Batch fermentation and fedbatch fermentation, with both free cells and immobilized cells, were compared to highlight the advantages of FBB fermentation. In batch mode, the D-LA production rate of FBB fermentation was 1.62 g/l/h, which was 37.29% higher than that of free-cell fermentation, and the D-LA optical purities of the two fermentation methods were above 99.00%. In fed-batch mode, the maximum D-LA concentration attained by FBB fermentation was 218.8 g/l, which was 37.67% higher than that of free-cell fermentation. Repeated-batch fermentation was performed to determine the long-term performance of the FBB system, and the data indicated that the average D-LA production rate was 1.62 g/l/h and the average yield was 0.98 g/g. Thus, hydrolyzed corn flour fermented by S. inulinus Y2-8 in a FBB may be used for improving D-LA fermentation by using ammonia water as the neutralizing agent.