• KSBB Journal
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• v.16 no.5
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• pp.511-515
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• 2001

In this paper, we development and operated a two-stage continuous stirred tank reactor (CSTR)/trickling biofilter(TBF)system for the long-term continuous treatment of trichloroethylene (TCE) using Burkholderia cepacia G4. In this reactor system. CDTR with cell recycle from TBF was coupled to the TBF for the reactivation of the cells deactivated during TCE degradation. The critical elimination capacity was determined to be 25.3 mg TCE/L day and the reactor has been stably operated for more than 1 months, which clearly represented that CSTR/TBF system can be used for long-term treatment of TCE.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.541-544
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• 2001

One of the most promising TCE treatment systems is trickling biofilter (TBF), in which monooxygenase, the corresponding enzyme for initiating growth substrate oxidation, fortuitously transforms TCE via cometabolism. TCE. however. is not easily treated by simple cometabolic biotransformation. This is mainly due to the toxicity of TCE to microbial cell and monooxygenase. In this study, we cleveloped and operated a two-stage CSTR/TBF system for the long-term continuous treatment of TCE. In the two-stage biotransfon11ation system, CSTR with cell recycle from TBR was coupled to the TBR for the reactivation of the cells deactivated during TCE degradation.

• KSBB Journal
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• v.14 no.4
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• pp.452-459
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• 1999

A two-stage continuous stirred tank reactor (CSTR)/trickling biofilter reactor (TBR) system was developed for the degradation of gas-phase trichloroethlene (TCE) using Methylosinus trichoporium OB3b. Mrthylosinus trichosporium OB3b was immobilized on activated carbons in TBR and the microbial growth reactor of a CSTR was coupled for the reactivation of the deactivated cells during TCE degradation. The effect of operation variables on TCE conversion and degradation rate were studied. At inlet TCE concentrations ranging from 10 to 80 $\mu$mol/L, TCE degradation rate was increased up to 525 mg TCE/Lㆍday with 75% conversion. The TCE degradation rates were also increased with increse in broth recycle flow rate, gas flow rate and dilution rate. When the temperature of TBR was changed from 3$0^{\circ}C$ to 15$^{\circ}C$, TCE degradation rate and TCE conversion were increased due to the enhanced TCE transfer from gas-phase. The two-stage reactor system was found to be stable and has been operated for more than 270 days.

• KSBB Journal
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• v.11 no.1
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• pp.58-64
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• 1996

The purpose of this study is to develop a continuous process for sorbitol production using Zymomonas mobilis immobilized in K-carra-geenan. The glutaraldehyde cross-linking of toluene-treated cells immobilized in alginate or chitin showed high enzyme stability for long period. However, loss of enzyme activity was observed at 23% during 210h. In order to investigate the stability of glucose-fructose oxidoreductase of cethyltrimethylammoniumbromide (CT AB) treated cells, the long term continuous process was carried out with Z. mobilis immobilized in K-carrageenan in the continuous stirred tank reactor(CSTR) and the packed bed reactor. The continuous production of sorbitol with the immobilized CT AB permeabilized cells in packed bed reactor was more stable than in CSTR. Two stage continuous process with CT AB treated cells of Z. mobilis immobilized in K-carrageenan was carried out at various dilution rates. At the first stage, the productivity was increased up to 15 g/ $\ell$ -h as dilution rate increased and decreased over 0.32$h^{-1}$ of dilution rate. Similarly, maximum productivity obtained at the second stage was 22g/$\ell$ -h at 0.32$h^{-1}$

• Journal of Korean Society of Environmental Engineers
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• v.31 no.12
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• pp.1075-1080
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• 2009

The partial lipid degradation with the saturation of double-bond at the acidogenesis stage is known to help subsequent methanogenesis during anaerobic digestion. Acidogenic reactions in an anaerobic sequencing batch reactor (ASBR) and a continuously stirred tank reactor (CSTR) were carried out to compare their performances. A mixture of two unsaturated (oleate and linoleate) and two saturated (palmitate and stearate) long-chain fatty acids (LCFAs) was used as a model substrate. Biomass retention in the ASBR contributed to the enhanced performance at hydraulic retention time (HRT) below 15 hr. Biomass retention in the ASBR contributed to the enhanced performance compared to CSTR even at shorter HRT. ASBR would be a proper reactor configuration for the acidogenesis of lipid-containing wastewater.

• Journal of Life Science
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• v.13 no.6
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• pp.970-975
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• 2003

Microbial trichloroethylene (TCE) degradation using trickling biofilter (TBF) is a cost-effective treatment method, in which monooxygenase (MO) fortuitously transforms TCE via cometabolism. Simple TBF, however, could not be stably operated for long-term treatment of TCE due to the contradictory characteristics of cometabolism. In this paper, microbial biocatalyst and biofilm reactor system, a two-stage continuous stirred tank reactor (CSTR)/TBF system using Burkholderia cepacia G4 and Methylosinus trichosporium OB3b, are evaluated for the long-term continuous treatment of TCE. The maximum TCE elimination capacities were in the range of 28 and 525 mg TCE/1$.$day. The reactor systems were stably operated for more than 3∼12 months.

• KSBB Journal
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• v.19 no.5
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• pp.406-409
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• 2004

Matrix Assisted Laser Desorption ionization Time of Flight (MALDI-TOF) was used for enzymes identification related to B -1,3-glucan synthesis. Agrobacterium sp. ATCC31750 was cultivated with two stage Continuous Stirrer Tank Reactor (CSTR) and the cells were harvested and their protein profiles were analysed by two dimensional electrophoresis. The specific enzyme spot was treated with trypsin and ana lysed by MALDI-TOF to get peptide molecular weight. The peptide molecular weights were matched with Agrobacterium tumefacience's Data Base from the matrix science site, then could identify the avaliable key enzymes. In this study, we identified key metabolite of synthesis of beta-1,3-glucan, such as glucose-6-phosphate isomerase, phosphoglucomutase, B-1,3-glucan synthase and glucokinase, and we also identified uracil phosphoribocyl transferase and Ribosome recycling factor also.

• KSBB Journal
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• v.15 no.5
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• pp.489-496
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• 2000

Several culture systems including batch, two-stage CSTR, semi-fed batch, and two-stage cyclic fed-batch were investigated for the efficient production of the Fab fraction of PDC-E2 specific human monoclonal antibody using high cell density recombinant E. coli. A two-phase batch system and a two-stage continuous system were examined to overcome plasmid instability problems, by separating the growth and the production stages. The cell density and productivity of the two-stage continuous culture was better than that of the two-phase batch fermentation. In the two-stage continuous culture system with DO-stat, the cell growth and the productivity were superior to those of the system without the DO control. Also, almost total plasmid stability was maintained in the two-stage continuous culture system. Modified M9 medium was selected as an optimum feeding medium for the fed-batch process, and the optimum C/N ratio determined to be 2:3. The optimum feeding rate was $0.6g/\ell/hr$ for a constant feeding strategy in semi-fed batch system. When the feeding medium was fed by pulsing, it was observed that more frequent pulsing resulted in improved cell growth. The linear feeding method was the most efficient of the various feeding methods tested. Finally, high cell density culture using a two-stage cyclic fed batch system with pH-stat was tried because the linear feeding method showed limitations in terms of obtaining high cell densities, and a cell density of $54 g/\ell$ was achieved. It was concluded that the two-stage cyclic fed batch system was the most efficient system for high cell density culture of the systems tested. However, productivity improvements were lower than expected due to the extremely high accumulations of acetate, although the low levels of residual glucose were maintained.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.487-490
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• 1991

In this study continuous alcohol fermentation of molasses by the recirculation system has investigated. After cultivation of yeast cells in the YPD medium with increasing the medium concentration from 10 to 183.5 g/l stepwisely, the fermentation medium was replaced by molasses. The maximum cell mass was 25 g/l, and the mean cell mass during the operation was 23.5g/1, which was 3.4 times higher compared with a conventional batch system. The optimum fermentation conditions with feeding molasses of 180 g/l were obtained when the fermentation was carried out at 500 rpm and at the dilution rate of 0.037 $h^{-1}$. Under these conditions we could safely operate the fermentor for 645 h without any trouble. The maximum alcohol productivity was 4.9 g$l\cdot h$ with an alcohol concentration of 53.9 g/l at the dilution rate of 0.091$h^{-1}$.