• KSBB Journal
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• v.6 no.1
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• pp.63-68
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• 1991

An auxotrophic regulatory mutant of Corynebacterium glutamicum ATCC 21674 produced 2.1-3.4g/1 of phenylalanine with 2.9-4.4g/l of tyrosine in the batch shake flask fermentations. At higher sugar concentration, the production of both amino acids was lower than that at low sugar concentration. There was a pronounced effect of temperature on the amino acid production. At $30^{\circ}C$, much higher levels of phenylalanine and tyrosine were produced than those at $37^{\circ}C$. The pH decrease in the shake flask fermentation was so fast that it was impossible to maintain a constant pH with calcium carbonate as a buffering agent. Even though the strains we have used are reported as tyrosine auxotrophs, they produced tyrosine and were able to grow on the minimal medium where no tyrosine was present.

• KSBB Journal
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• v.8 no.2
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• pp.164-171
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• 1993

The production of extracellular polysaccharide by Methylomonas mucosa (NRRL B-5696) was investigated. The microorganism uses methanol as the carbon source for their growth and produces exopolysaccharides. The productivity of exopolysaccharides was investigated under various culture modes: batch, fed-batch and continuous culture. In flask culture the growth of cell mass and the production of polysaccharide were inhibited at above 1% (v/v) methanol. At 1%(v/v) methanol maximum specific growth rate was obtained. As C/N ratio (g methanol/g ammonium sulfate) increased, polysaccharide production increased and cells mass decreased. Magnesium ion was also found to be essential for the polysaccharide production. In batch culture the production of polysaccharides was more affected by the specific growth rate than the cell concentration. In fed-batch culture the concentration of polysaccharide was 4 times higher than that of batch culture, but the yield was lower. The productivity of fed-batch with continuous feeding was higher than that of batch or fed-batch with intermittent feeding. This is due to no methanol limitation or inhibition that used to occur in fed-batch culture with intermittent feeding. In continuous culture pure oxygen was supplied to avoid the oxygen limitation. As the dilution rate in- creased up to 0.21 h-1, the yield and productivity increased. The solution viscosity of the produced polysaccharide obtained from above increased exponentially with the concentration of polysaccharide.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.277-282
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• 1989

Xanthan gum is a biopolymer produced by Xanthomonas campestris. In xanthan gum fermentation, the fermentation broth changes to highly viscous non-Newtonian fluid as xanthan gum concentration increases. Maximum xanthan gum concentration is limited by high viscosity of the broth since mass transfers of nutrient and oxygen are inhibited. Int this study the mass transfer effects were investigated in batch and fed-batch fermentations at various agitation speeds and by separate oxygen transfer experiments. Xanthan gum production rate was observed to be largely dependent on oxygen transfer coefficient; while cell growth rate was not affected highly by this factor.

• Microbiology and Biotechnology Letters
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• v.28 no.6
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• pp.355-360
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• 2000

A UVmutant of Candida rugosa IF00750 was made and used to convert butYlic acid to D-$\beta$-hydroxybutyric acid(D-$\beta$-HBA). Major regulating factors for D-$\beta$-HBA fennentation were investigated via chemostat analyses. The maximum specific productivity was achieved at a specific growth rate of $0.06h^{-1}$ where the glucose and butyric acid concentrations in the fermentor were 10 g/L and 8.7 g/L. respectively. A fed-batch fennentation was performed with maintenance of the optimum glucose and butyric acid concentrations. The D-$\beta$-HBA concentration after 120 h of cultivation reached 12.4 g/L, which was 4.7 times greater illan the concentration obtained by batch fermentation.

• KSBB Journal
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• v.20 no.5 s.94
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• pp.350-354
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• 2005

In order to maximize hydrogen production by Enterobacter cloacae YJ-1, anaerobic hydrogen producing bacteria, the medium composition was optimized. Glucose was better than other carbon sources in hydrogen production and its production was 975.4 mL/L at $2\%$ (w/v) for 48 h. Organic nitrogen sources were more effective than inorganic nitrogen sources and also yeast extract among organic nitrogens was the most effective in hydrogen production. Among metal ions, $Na_2MoO_4$ was most effective, and its production was 1753.3mL/L at $0.04\%$ (w/v). Addition of amino acid was very effective with compare to another components of medium, and cystein was most effective among them. Under the optimum medium obtained in batch culture, semi-batch culture in order to produce continuous hydrogen was run. The highest hydrogen production was earned at $3\%$(w/v) of glucose and the amount was 2215.4 mL/L.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.614-618
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• 1992

The batch and fed-batch cultivations of Brevibacteriurn CHI were carried out for the production of nitrile hydratase. In batch culture, with pH control the cell mass and the specific activity increased more 20% and 30%. respectively. The maximum growth rate was obtained at a glucose concentration of $20g/{\ell}$ because of substrate inhibition. The fed-batch culture of Brevibacteriurn CHI with constant substrate feeding gave a cell density of up to $68g/{\ell}$ and nitrile hydratase activity was maintained at above 6.1units/mg. The cell growth yield on carbon .source was ca. 0,68 g/g glucose consumed. The total nitrile hydratase activity in this fed-batch mode increased up to 414.8 units/m${\ell}$, which amounted to 4.4 times that of the batch culture.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.111-115
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• 2004

Reuterin production efficiency of Lactobacillus reuteri, which converts glycerol into reuterin (antimicrobial substance) under anaerobic condition, was examined. When compared at $32,\;37,\;and\;42^{\circ}C$, production rate and total amount produced increased with increasing incubation temperature. Reuterin production terminated earlier at $42^{\circ}C$ than at $32\;and\;37^{\circ}C$. Presence of various amino acids in the reaction mixture generally decreased reuterin production, whereas proline did not inhibit reuterin production. A continuous-type reactor in which glycerol was passed through the chamber containing L. reuteri cells produced greater amount of reuterin than when batch-type process was used.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.919-926
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• 2009

Enrichment of anaerobic ammonium oxidation (ANAMMOX) bacteria is the essential step for operating full-scale ANAMMOX bioreactor because adding a significant amount of seeding sludge is required to stabilize the ANAMMOX reactor. In this study, the enrichment of ANAMMOX bacteria from an activated sludge using sequencing batch reactor was conducted and verified by analyzing changes in the microbial community structure. ANAMMOX bacteria were successfully enriched for 70 days and the substrate removal efficiencies showed 98.5% and 90.7% for $NH_4\;^+$ and $NO_2\;^-$ in the activity test, respectively. The phylogenetic trees of Planctomycetes phylum showed that the diverse microbial community structure of an activated sludge was remarkably simplified after the enrichment. All 36 clones, obtained after the enrichment, were affiliated with ANAMMOX bacteria of Candidatus Brocadia (36%) and Candidatus Anammoxoglobus (64%) genera. The quantification using real-time quantitative PCR (RTQ-PCR) revea ed that the 16S rDNA concentration of ANAMMOX bacteria was 74.8% compared to the granular ANAMMOX sludge obtained from an upflow ANAMMOX sludge bed reactor which had been operated for more than one year. The results of molecular analysis supported that the enriched sludge could be used as a seeding sludge for a full-scale ANAMMOX bioreactor.

• KSBB Journal
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• v.9 no.4
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• pp.436-442
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• 1994

The production of itaconic acid by Aspergillus terreus NRRL 1960 was studied. The optimal culture conditional such as pH, inoculum size and medium composition were established. Maximum production of itaconic acid, $19.18g/\ell$, was obtained when the cultivation was carried out at $37^{\circ}C$ and pH 2.5 for 7days, with medium containing 5%(w/v) glucose, 0.5%(w/v) NH4Cl, 0.2%(w/v) yeast extract 0.1%(w/v) CaC12, 0.1%(w/v) MgSO4 and 0.2%(w/v) NaCl. A proper medium for inoculum culture was found to be 2%(w/v) malt extract. The batch production of itaconic acid with free cells in a stirredtank reactor was not efficient compared to the shake-flask culture.

• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.46-50
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• 2003

Lactococcus lactis SA72 from Jeot-gal (Korean traditional fermented fish foods) produces lacticin SA72. The influence of several parameters on the fermentative production of lacticin SA72 by Lactococcus lactis SA72 was studied. MRS medium among several media was selected for enhanced bacteriocin production. The mean growth rate and bacteriocin productivity of L. lactis SA72 increased as the initial pH of the media increases. The highest lacticin SA72 activity was detected 3,200 AU/ml at pH 6.0, $32^{\circ}C$, and 1% (inoculum size, v/v) in the jar fermenter. Enhanced production of lacticin SA72 was investigated by a fed-batch cultivation with the intermittent feeding of the concentrated glucose solution. Under the optimized conditions, lacticin SA72 activity finally reached to 6,400 AU/ml.