During the production of ε-poly-L-lysine (ε-PL) in fed-batch fermentation, the decline of ε-PL synthesis often occurs at middle or late phase of the fermentation. To solve the problem, we adopted two strategies, namely pH shift and feeding yeast extract, to improve the productivity of ε-PL. ε-PL productivity in fermentation by pH shift and feeding yeast extract achieved 4.62 g/(L x d) and 5.16 g/(L x d), which were increased by 27.3% and 42.2% compared with the control ε-PL fed-batch fermentation, respectively. Meanwhile, ε-PL production enhanced 36.95 g/L and 41.32 g/L in 192 h with these two strategies, increased by 27.4% and 42.48% compared to the control, respectively. ε-PL production could be improved at middle or late phase of fed-batch fermentation by pH shift or feeding yeast extract.
Batch Cell Culture Techniques ; Fermentation ; Industrial Microbiology ; Nitrogen ; chemistry ; Polylysine ; biosynthesis

To enhance the production of ε-poly-L-lysine (ε-PL) by improving dissolved oxygen level of the fermentation system, different oxygen-vectors were added to broth and n-dodecane was screened as the best oxygen-vector. The best amount of n-dodecane was 0.5% (V/V) and the best time was at start of the fermentation. In a fed-batch fermentation in a 5 L bioreactor, ε-PL concentration reached a maximum of (30.8 ± 0.46) g/L and the dry cell weight obtained was (33.8 ± 0.29) g/L, increasing by 31.6% and 20.7% compared with the control group, respectively. This improvement can be related to 0.5% n-dodecane could maintain dissolved oxygen concentration > 32% of air concentration compared with 23.8% in ε-PL production phase, and the production of a main by-product, poly-L-diaminopropionic acid, fell by 31%. These results indicated that the dissolved oxygen level in the broth was improved by adding n-dodecane, which can inhibit the by-product production and improve the biosynthesis of ε-PL.
Alkanes ; chemistry ; Batch Cell Culture Techniques ; Bioreactors ; Fermentation ; Oxygen ; chemistry ; Polylysine ; biosynthesis

A comparative study of batch and repeated batch process was carried out for astaxanthin fermentation of Phaffia rhodozyma to develop a more economical method for astaxanthin industrial production. In shaking flask fermentation, the change of biomass and astaxanthin production was studied to compare the five-day cycle with four-day cycle of repeated batch culture of P. rhodozyma. Astaxanthin production increased at first and then decreased subsequently in seven cycles, yet the yield of astaxanthin in the next six cycles remains higher than that of the first cycle. Comparing the average production of astaxanthin in the seven cycles, four-day cycle performed even better than five-day cycle. Subsequently, a repeated fed-batch process was used in a 5-1 bioreactor. The experimental data showed that biomass and astaxanthin production of the second batch could reach the level of the first batch, no matter that the carbon source was glucose or hydrolysis sugar of starch. This result showed that this strain had good stability, and thus repeated batch and fed-batch process could be applied in astaxanthin fermentation for economical purpose.
Basidiomycota ; genetics ; metabolism ; Batch Cell Culture Techniques ; methods ; Bioreactors ; microbiology ; Fermentation ; Industrial Microbiology ; methods ; Xanthophylls ; biosynthesis

In recent years, the demand of biologics has increased rapidly. Cell culture process with perfusion mode has become more and more popular due to its high productivity, good quality and high efficiency. In this paper, the unique operation and the details of process optimization for perfusion culture mode are discussed by comparing with traditional batch culture process. Meanwhile, the progress and strategies in the development and optimization of perfusion culture process in recent years are summarized to provide reference for the future development of mammalian cell perfusion culture technology.
Animals ; Batch Cell Culture Techniques ; trends ; Bioreactors ; standards ; CHO Cells ; Cricetulus ; Mammals ; Perfusion

With various diseases ravaging internationally, the demands for recombinant adenoviral vector (Adv) vaccines have increased dramatically. To meet the demand for Adv vaccine, development of a new cell culture process is an effective strategy. Applying hyperosmotic stress in cells before virus infection could increase the yield of Adv in batch culture mode. Emerging perfusion culture can significantly increase the yield of Adv as well. Therefore, combining the hyperosmotic stress process with perfusion culture is expected to improve the yield of Adv at high cell density. In this study, a shake flask combined with a semi-perfusion culture was used as a scaled-down model for bioreactor perfusion culture. Media with osmotic pressure ranging from 300 to 405 mOsm were used to study the effect of hyperosmotic stress on cell growth and Adv production. The results showed that using a perfusion culture process with a hyperosmotic pressure medium (370 mOsm) during the cell growth phase and an isosmotic pressure medium (300 mOsm) during the virus production phase effectively increased the yield of Adv. This might be due to the increased expression of HSP70 protein during the late phases of virus replication. The Adv titer in a bioreactor with such a process reached 3.2×10¹⁰ IFU/mL, three times higher than that of the traditional perfusion culture process. More importantly, this is the first time that a strategy of combining the hyperosmotic stress process with perfusion culture is applied to the production of Adv in HEK 293 cells. It also reveals the reason why the hyperosmotic stress process increased the yield of Adv, which may facilitate the process optimization of for producing other Adv in HEK 293 cells.
Humans ; HEK293 Cells ; Genetic Vectors/genetics* ; Batch Cell Culture Techniques ; Bioreactors ; Perfusion

Carbon-limited continuous culture was used to study the relationship between the growth of Aspergillus niger and the production of glucoamylase. The result showed that when the specific growth rate was lower than 0.068 h(-1), the production of glucoamylase was growth-associated, when the specific growth rate was higher than 0.068 h(-1), the production of glucoamylase was not growth-associated. Based on the result of continuous culture, the Monod dynamics model of glucose consumption of A. niger was constructed, Combining Herbert-Pirt equation of glucose and oxygen consumption with Luedeking-Piret equation of enzyme production, the black-box model of Aspergillus niger for enzyme production was established. The exponential fed-batch culture was designed to control the specific growth rate at 0.05 h(-1) by using this model and the highest yield for glucoamylase production by A. niger reached 0.127 g glucoamylase/g glucose. The black-box model constructed in this study successfully described the glucoamylase production by A. niger and the result of the model fitted the measured value well. The black-box model could guide the design and optimization of glucoamylase production by A. niger.
Aspergillus niger ; metabolism ; Batch Cell Culture Techniques ; Carbon ; Culture Media ; Glucan 1,4-alpha-Glucosidase ; biosynthesis ; Glucose ; Industrial Microbiology ; methods ; Oxygen

Adenovirus vectors are promising delivery systems for gene therapy. We established a new process for clinic trial of recombinant adenovirus vectors using a novel disposable bioreactor. The suspension HEK293 cells were inoculated into a 5 L disposable bioreactor with parameters control of pH, DO, agitation and temperature. After 6 days of a fed-batch culture, the final cell density reached 2.0 x 10(6) cells/mL. The culture was infected with Ad-IFNγ at an MOI of 30. The harvest was performed at approximately 48 h post-infection and crude viral lysate was obtained after 3 freeze/thaw cycles and centrifugation. The maximum titers of crude viral lysate was 1.49 x 10(13) Infectious units (IFU) and the bulk product specific was 3,800 IFU/cell. Purified Ad-IFNγ by anion-exchange chromatography and the final recovery of infectious unit reached 35.9%. The result demonstrates that an efficient and stable process of producing Ad-IFNγ using a disposable fed-batch bioreactor is established.
Adenoviridae ; growth & development ; Batch Cell Culture Techniques ; Bioreactors ; Cell Count ; Genetic Therapy ; Genetic Vectors ; HEK293 Cells ; Humans ; Virus Cultivation ; methods

Bioreactors have been central in monoclonal antibodies and vaccines manufacturing by mammalian cells in suspension culture. Numerical simulation of five impeller combinations in a stirred bioreactor was conducted, and characteristics of velocity vectors, distributions of gas hold-up, distributions of shear rate in the bioreactor using 5 impeller combinations were numerically elucidated. In addition, genetically engineered CHO cells were cultivated in bioreactor installed with 5 different impeller combinations in fed-batch culture mode. The cell growth and antibody level were directly related to the maximum shear rate in the bioreactor, and the highest viable cell density and the peak antibody level were achieved in FBMI3 impeller combination, indicating that CHO cells are sensitive to shear force produced by impeller movement when cells were cultivated in bioreactor at large scale, and the maximum shear rate would play key roles in scaling-up of bioreactor at industrial scale.
Animals ; Batch Cell Culture Techniques ; Bioreactors ; standards ; CHO Cells ; Cell Count ; Computer Simulation ; Cricetinae ; Cricetulus ; Industrial Microbiology ; instrumentation ; methods

3-Hydroxypropionic acid is an important building block to synthesize lots of industrially valuable chemicals. In this study, we firstly investigated the effects of cell, substrate and product concentrations on biosynthesis of 3-hydroxypropionic acid from 1,3-propanediol by Gluconobacter oxydans ZJB09112 in 50-mL shake flask containing 10 mL transformation liquid. To avoid the inhibition of substrate and product, we adopted fed-batch biotransformation and fed-batch biotransformation coupled with in situ product removal in 2-L bubble column reactor containing 1 L transformation liquid. The results show that high concentrations of substrate and product could inhibit the biotransformation by decreasing the initial reaction rate, and the optimal reaction conditions were as follows: cell concentration 6 g/L, pH 5.5. Fed-batch biotransformation in which the substrate concentration was maintained at 15-20 g/L could obtain product concentration of 60.8 g/L after 60 h, which gave a productivity of 1.0 g/(Lh) and a yield of 84.3%. Furthermore, fed-batch biotransformation coupled with in situ product removal could achieve the total product concentration of 76.3 g/L after 50 h, which gave a productivity of 1.5 g/(L x h) and a yield of 83.7%. The results obtained here may be useful for the application of G. oxydans in biocatalysis industry by using its characteristic of incomplete oxidation of alcohols.
Batch Cell Culture Techniques ; Biotransformation ; Gluconobacter oxydans ; metabolism ; Lactic Acid ; analogs & derivatives ; biosynthesis ; Oxidation-Reduction ; Propylene Glycols ; metabolism

Sugarcane bagasse modified by polyethylenimine (PEI) and glutaraldehyde (GA) was used as a carrier to immobilize Clostridium acetobutylicum XY16 in the process of butanol production. The effects of chemically modified sugarcane bagasse on batch and repeat-batch fermentations were investigated. Batch fermentation was conducted with an addition of 10 g/L modified sugarcane bagasse and 60 g/L glucose, resulting in a high solvent concentration of 21.67 g/L and productivity of 0.60 g/(L x h) with the treatment of 4 g/L PEI and 1 g/L GA. Compared to the fermentations by free cells and immobilized cells on unmodified sugarcane bagasse, the productivity increased 130.8% and 66.7%, respectively. The fibrous-bed bioreactor also maintained a stable butanol production during repeat-batch fermentations, achieving a maximum productivity of 0.83 g/(L x h) with a high yield of 0.42 g/g.
Batch Cell Culture Techniques ; Bioreactors ; Butanols ; metabolism ; Cells, Immobilized ; Cellulose ; metabolism ; Clostridium acetobutylicum ; metabolism ; Fermentation ; Saccharum ; chemistry