• Journal of Microbiology and Biotechnology
• /
• v.21 no.9
• /
• pp.972-978
• /
• 2011

In this study, we investigated the performance of an immobilized ${\beta}$-galactosidase inclusion bodies-containing Escherichia coli cell reactor, where the cells were immobilized in alginate beads, which were then used in repeated-batch operations for the hydrolysis of o-nitrophenyl-${\beta}$-D-galactoside or lactose over the long-term. In particular, in the Tris buffer system, disintegration of the alginate beads was not observed during the operation, which was observed for the phosphate buffer system. The o-nitrophenyl-${\beta}$-D-galactoside hydrolysis was operated successfully up to about 80 h, and the runs were successfully repeated at least eight times. In addition, hydrolysis of lactose was successfully carried out up to 240 h. Using Western blotting analyses, it was verified that the ${\beta}$-galactosidase inclusion bodies were sustained in the alginate beads during the repeated-batch operations. Consequently, we experimentally verified that ${\beta}$-galactosidase inclusion bodies-containing Escherichia coli cells could be used in a repeated-batch reactor as a biocatalyst for the hydrolysis of o-nitrophenyl-${\beta}$-D-galactoside or lactose. It is probable that this approach can be applied to enzymatic synthesis reactions for other biotechnology applications, particularly reactions that require long-term and stable operation.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.1
• /
• pp.107-113
• /
• 2012

To develop a practical and cost-effective medium for bioethanol production from the hydrolysate of seaweed Sargassum sagamianum, we investigated the feasibility and performance of bioethanol production in CSL (corn-steep liquor)-containing medium, where yeast Pichia stipitis was used and the repeated batch was carried out in a surface-aerated fermentor. The optimal medium replacement time during the repeated operation was determined to be 36 h, and the surface aeration rates were 30 and 100 ml/min. Under these conditions, the repeated-batch operation was successfully carried out for 6 runs (216 h), in which the maximum bioethanol concentrations reached about 11-12 g/l at each batch operation. These results demonstrated that bioethanol production could be carried out repeatedly and steadily for 216 h. In these experiments, the total cumulative bioethanol production was 57.9 g and 58.0 g when the surface aeration rates were 30 ml/min and 100 ml/min, respectively. In addition, the bioethanol yields were 0.43 (about 84% of theoretical value) and 0.44 (about 86% of theoretical value) when the surface aeration rates were 30 ml/min and 100 ml/min, respectively. CSL was successfully used as a medium ingredient for the bioethanol production from the hydrolysate of seaweed Sargassum sagamianum, indicating that this medium may be practical and cost-effective for bioethanol production.

• KSBB Journal
• /
• v.15 no.3
• /
• pp.247-253
• /
• 2000

This study was aimed to enhance polycyclic aromatic hydrocarbon(PAHS) biodegradation rate by repeated-batch treatment using immobilized cells of Phanerochaete chrysosporium. In the repeated-batch operations with 30 mg/L of pyrene the maximum degradation rate was 6.58 mg/L day. As the number of batches increased the concentration of immobilized cells significantly decreased and the degradation rate and specific acitivity gradually increased to a maximum value and then decreased. To have PAH degradation activity and cell mass recovered one batch of cultivation using the growth medium instead of the PAH-degrading medium was carried in the course of repeated-batch operations. This maximum degradation rates of pyrene and anthracene were 4.29 and 4.46 mg/L$.$day respectively. Overall the rate of PAH degradation could be enhanced 2.5-30 folds by using immobilized cells compared to the case of using suspended cells.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10b
• /
• pp.1277-1283
• /
• 1990

The iterative learning control synthesized in the frequency domain has been utilized for temperature control of a batch reactor. For this purpose, a feedback-assisted generalized learning control scheme was constructed first, and the convergence and robustness analyses were conducted in the frequency domain. The feedback-assisted learning operation was then implemented in a bench scale batch reactor where reaction heat is simulated using an electric heater. As a result, progressive reduction of temperature control error could be obviously observed as batch operation is repeated.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.11
• /
• pp.1486-1493
• /
• 2012

In this study, we investigated whether galactooligosaccharide (GOS) can be stably and steadily synthesized using immobilized ${\beta}$-galactosidase (${\beta}$-gal) inclusion body (IB)-containing E. coli cells during long-term repeated-batch operation. To improve the operational stability of this enzyme reactor system, immobilized E. coli cells were crosslinked with glutaraldehyde (GA) after immobilization of the E. coli. When we treated with 2% GA for E. coli crosslinking, GOS production continued to an elapsed time of 576 h, in which seven batch runs were operated consecutively. GOS production ranged from 51.6 to 78.5 g/l ($71.2{\pm}10.5$ g/l, n = 7) during those batch operations. In contrast, when we crosslinked E. coli with 4% GA, GOS production ranged from 31.5 to 64.0 g/l ($52.3{\pm}10.8$, n = 4), and only four consecutive batch runs were operated. Although we did not use an industrial ${\beta}$-gal for GOS production, in which a thermophile is used routinely, this represents the longest operation time for GOS production using E. coli ${\beta}$-gal. Improved stability and durability of the cell immobilization system were achieved using the crosslinking protocol. This strategy could be directly applied to other microbial enzyme reactor systems using cell immobilization to extend the operation time and/or improve the reactor system stability.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.410-413
• /
• 2001

In this study a repeated batch production of lactic acid was investigated for the purpose of reducing amount of yeast extract dosage. First batch operation was performed with nutrient rich media(glucose 100-150 g/${\ell}$, and high yeast extract contents; 15 g/${\ell}$), and subsequential batch operations were performed with nutrient poor media(glucose 100-150 g/${\ell}$, and reduced yeast extract contents; 4-5 g/${\ell}$). Volumetric productivities(6.03-6.20 g/${\ell}{\cdot}h$) and substrate conversion rate(94-98%) of eve η subsequential batch operation were maintained with the same level of first batch operation(6.19 g/${\ell}{\cdot}h$, and 99%, respectively), when concentrations of glucose and yeast extract were 100, and 4 g/${\ell}$ respectively.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.12
• /
• pp.1250-1256
• /
• 2011

In this study, Bacillus licheniformis cells were immobilized by entrapment in calcium alginate beads and were used for production of alkaline protease by repeated batch process. In order to increase the stability of the beads, the immobilization procedure was optimized by statistical full factorial method, by which three factors including alginate type, calcium chloride concentration, and agitation speed were studied. Optimization of the enzyme production medium, by the Taguchi method, was also studied. The obtained results showed that optimization of the cell immobilization procedure and medium constituents significantly enhanced the production of alkaline protease. In comparison with the free-cell culture in pre-optimized medium, about 7.3-fold higher productivity was resulted after optimization of the overall procedure. Repeated batch mode of operation, using optimized conditions, resulted in continuous production of the alkaline protease for 13 batches in 19 days.

• Microbiology and Biotechnology Letters
• /
• v.17 no.6
• /
• pp.624-628
• /
• 1989

A study on the citric acid production using Saccharomycopsis lipolytica (NRRL Y7576) was carried out in shake-flasks, air-lift and membrane recycle bioreactors. The cells entrapped in Ca-alginate beads were used in shake-flasks and air-lift reactor. Repeated batch fermentation in shake-flasks was successfully performed for 34 days and resulted in a yield of 54%. Increased yield (63%) was obtained in the air-lift reactor operation using nitrogen deficient medium (NDM). In the membrane recycle bioreactor operation, the maximal dry cell mass concentration was 39 g/1 at a dilution rate of 0.02 h$^{-1}$ and the yield with NDM was higher than that with growth medium. In addition, the yield and volumetric productivity with pure oxygen supply were greatly improved compared with those with air supply.

• Journal of environmental and Sanitary engineering
• /
• v.11 no.2
• /
• pp.1-7
• /
• 1996

The behavior of total organic carbon (TOC) and phosphate were observed for 15 days with immobilized activated sludge using polyacrylamide (PAA) by sequencing batch reactor (SBR). In the preparation of immobilized sludge by PAA, it was found that suitable acrylamide concentration for actual wastewater treatment was to be 15% through the batch test. When SBR system was operated in the repeated aerobic and anaerobic conditions, TOC removal efficiency was 92%. The uptake rate of phosphate was increased from 1.78 mg-P/g cell/hr on the 5th day of acclimation to 2.5 mg-P/g cell/hr on the 15th day of acclimation. And the total phosphorus content in PAA bead was increased from 40 mg-P/g cell on the 1st day of operation to 55 mg-P/g cell on the 15th day of operation. From this study, lowering the volume of aeration tank was possible when PAA bead was used in wastewater treatment and long operation was also possible without the settler.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.3
• /
• pp.366-374
• /
• 2015

Herein, we established a repeated-batch process for ethanol production from glycerol by immobilized Pachysolen tannophilus. The aim of this study was to develop a more practical and applicable ethanol production process for biofuel. In particular, using industrial-grade medium ingredients, the microaeration rate was optimized for maximization of the ethanol production, and the relevant metabolic parameters were then analyzed. The microaeration rate of 0.11 vvm, which is far lower than those occurring in a shaking flask culture, was found to be the optimal value for ethanol production from glycerol. In addition, it was found that, among those tested, Celite was a more appropriate carrier for the immobilization of P. tannophilus to induce production of ethanol from glycerol. Finally, through a repeated-batch culture, the ethanol yield (Y_e/g) of 0.126 ± 0.017 g-ethanol/g-glycerol (n = 4) was obtained, and this value was remarkably comparable with a previous report. In the future, it is expected that the results of this study will be applied for the development of a more practical and profitable long-term ethanol production process, thanks to the industrial-grade medium preparation, simple immobilization method, and easy repeated-batch operation.