• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.525-532
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• 2020

A continuous fermentation process was carried out to enhance hyaluronic acid (HA) production using Streptococcus zooepidemicus cells. During the 1st stage continuous operation from 8 h with a dilution rate of 0.029/h (D1), HA was produced in the range of 7.5-10 g/l. During the 2nd stage from 44 h with a dilution rate of 0.036/h (D2), HA production (8.28 g/l) was initially reduced to a small extent due to increase of dilution rate from D1 to D2, and then a new pseudo-steady state was formed within a few hours with a concurrent small variations of HA production. The HA amount produced during the latter part of the 2nd stage was stably maintained in the range of 8.28-9.48 g/l, about 4.7% less amount compared to the 1st stage. Due to 24% increase of dilution rate from D1 to D2, however, maximum volumetric productivity (DP) amounting to 0.341 g/l/h was obtained at 96 h during the 2nd stage. This maximum productivity obtained from the continuous culture turned out only a small increase (3%) as compared to the corresponding batch fermentation. However, it should be noted that, in the case of batch process, one run typically consists of serial stages of growth culture plus one final production culture. This implies that, if the continuous fermentation that practically needs no dead time necessary for the multi-stage growth cultures is run for longer period, the total amount of the accumulated HA would be far greater than the amount obtained from the corresponding batch culture performed for the identical period.

• KSBB Journal
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• v.16 no.5
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• pp.474-479
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• 2001

Fed-batch culture, single stage and two stage continuous cultures of Corynebacterium glutamicum SH 35 for the production of $_{L}$-Iysine were performed and compared. In the case of fed batch culture, $_{L}$-Iysine concentration, $_{L}$-Iysine yield and $_{L}$-Iysine productivity was 129.2 g/L, 47.0% and 3.08 g/L/h, respectively. In a single-stage continuous culture, optimum dilution rate and pH was 0.1 h$^{-1}$ and 6.9, respectively, and optimum concentration of sugar and ammonium sulfate in a medium reservoir was 108 g/L and 25 g/L, respectively. Under the optimized conditions, 67 of cell concentration($OD_{610}$), 44.2 g/L of lysine concentration, 41% of $_{L}$-Iysine yield and 4.39 g$L^{-1}$ of $_{L}$-Iysine productivity were obtained. In a two-stage continuous culture, optimum dilution rate was 0.075 $h^{-1}$. Under the conditions, 103 of cell concentration($OD_{610}$) 84.0g/L of $_{L}$-Iysine concentration and 46% of $_{L}$-Iysine yield were obtained.

• KSBB Journal
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• v.23 no.3
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• pp.213-218
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• 2008

The present study was to investigate the continuous production of alcohol using immobilized carrier manufactured by polymeric materials. Fermentation runs with a crushed rice, with constituents recovered from batch culture and with ones from continuous culture were thus compared. The performances of immobilized carrier were governed by sandwitched synthetic polymers, the evolution of the continuous culture was steadily governed by the production of alcohol in the lag time of batch culture. The main focus was set on the enhancement of the alcohol production by an newly-developed polymeric forms. This polymeric form led to a drastic increase of the microorganism and the production cost in the continuous reactor was thereby reduced. The sandwitched polymeric-formed carrier, which was resistant to external environments, serves as an interesting alternative to maintain the stability of biological process. These whole results were discussed with the aim to better understand the continuous process implied in the microorganism's build-up during cultivation of fermentation broth.

• KSBB Journal
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• v.9 no.1
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• pp.85-90
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• 1994

The Gellan-type polysaccharide produced by Pseudomonas elodea(ATCC 31461) is one of the new heteropolysaccharides, having useful properties as gelling, suspending, stabilizing, emulsifying and binding agents in aqueous systems. Medium compositions for growth stage and production stage are improved. The problems of low cell concentration and poor productivity in highly viscous fermentation were attributed to inadequate mixing accompanied by insufficient oxygen transfer. During continuous culture, cell growth and polysaccharide production were greatly affected by the apparent viscosity, and they showed oscillation behavior, i.e. as the product concentration increases, cell concentration decreases. With improved culture conditions, the productivity of continuous culture increased up to 0.6g/$\ell$/hr(6-fold that of batch culture ) at dilution rate, D=$0.14hr^{-1}$.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.523-527
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• 2012

This study was performed to determine optimum conditions of semi-continuous cultivation of chlorella sp. FC-21 cultivated under red light emitting diode (LED). Semi-continuous cultivation was conducted using red LED because red LED was found to be the best light source for chlorella sp. FC-21. During cultivation, phosphate and nitrogen were quickly diminished where cell concentration of chlorella was inversely proportional to the concentrations of phosphate and nitrogen in culture solution. To increase the period of dilution of culture solution, additional amounts of phosphate and nitrogen were inserted in the culture solution to increase the concentrations of phosphate and nitrogen. The cell concentrations of chlorella increased in the modified culture, but cell diameter was diminished as the dilution of culture was periodically conducted. When considered the cell concentration and cell diameter during the cultivation, amount of biomass produced was maintained constant.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.196-202
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• 1992

Zoogloea ramigera 115 was selected for the production of viscous microbial polysaccharide for bioflocculants usage. Batch, fed-batch, and continuous culture processes were examined with regard to the high biopolymer production. Several carbon sources were tested, including glucose, lactose, molasses, and cheese whey. The C/N ratio of 90 was most effective for biopolymer production from glucose, while the C/N ratios of 30 for lactose and 60 for both molasses and cheese whey substrate gave a maximum production. Fed batch culture proved more effective to increase final biopolymer concentration than batch culture. Continuous fermentation with two stages modifying C/N ratio increased the productivity. The production rates were a maximum at dilution rate of 0.048 $hr^{-1}$ for molasses and at 0.096 $hr^{-1}$for cheese whey.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.61-65
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• 1990

Lectin related inducer can enhance IgG$_1$ production rate from murine hybridoma cells by employing step-feeding of serum free media with producing about 40 mg/$\ell$ of monoclonal antibodies. This step-feeding perfusion process also proves to be able to cutivate animal cells when serum free media can not support the growth of these cells in perfusion process, as well as to improve production rate. This process yields about 28 x 10$^{-10}$ mg of MAb/cells/h compared to 11.1 x 10$^{-10}$ and 4.0 x 10$^{-11}$ mg/cells/h for perfusion process and batch cultivation with 10% serum containing media, respectively.

• Clean Technology
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• v.4 no.1
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• pp.45-59
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• 1998

Continuous immobilized-cell culture was carried out for the production of kasugamycin, a secondary metabolite by a filamentous bacteria, Streptomyces kasugaensis, with an intention of reducing waste generation. A sporulation medium was developed for production of bulk amounts of spores, and the spores were entrapped into celite biosupports for immobilization. It was possible to effectively keep the immobilized-cells inside the reactor during the continuous culture by an efficient immobilized cell separator of decantor type on the outlet of the fermentor. Using this continuous immobilized-cell fermentor system, we investigated the effects of feed substrate and phosphate concentrations on kasugamycin production and chemical oxygen demand(COD). Comparing with the conventional suspended-cell batch culture, the kasugamycin productivity was observed to increase by 2.5 times, whereas COD per unit kasugamycin production decreased by 2.3 times in the continuous immobilized-cell culture. Based on these results, the continuous immobilized-cell system was considered to be a cleaner bioprocess than the conventional batch suspended-cell system.

• KSBB Journal
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• v.10 no.4
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• pp.401-405
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• 1995

An open pond type photobioreactor for mass cultivation of S. platensis was designed and the growth parameters from different cultivation processes were compared. 0.30(1/day) of specific growth rate and 1.69(g/$\ell$) of maximum cell density were obtained from batch cultivation. In fed-batch cultivation, specific growth rate and maximum cell density were estimated as 0.22(1/day) and 1.75(g/$\ell$), respectively. Maximum biomass productively from continuous cultivation was obtained as 0.44 (g/$\ell$/day). It proves that an outdoors-mass cultivation of S. platensis considering optimal environmental condition is economically feasible. In addition, the biomass productivity was studied in two different mixing systems such as agitation and air sparging methods. The biomass productivity by an agitation method was better than that in an air sparging method.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.1
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• pp.73-78
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• 2001

The biological carbon dioxide fixation using microalgae and photo-bioreactor has been known as an effective carbon dioxide reduction technology. As algae has many other environmental factor for its growth, the desirable cultivation factors were investigated using a green alga, Euglena gracilis Z. In this study, Euglena gracilis Z showed good $CO_2$ fixation ability in high $CO_2$ concentration of 10-20% and it contained the high protein and vitamin E enough to be used as fodder. For the mass cultivation, the continuous and semi-continuous cultivation methods were employed. The optimum hydraulic retention time (HRT) for the continuous cultivation was 4 days at carbon dioxide concentration of 10%. In this condition, the final cell number was $3.57{\times}10^6/m{\ell}$. The growth of Euglena gracilis Z increased according to the light intensity.