• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.700-703
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• 2001

The influence of process conditions on highly branched glucooligosaccharides production by mixed culture of Leuconostoc mesenteroides ATCC 13146 and Lipomyces starkeyi ATCC 74054 was studied. We divided the batch culture fermentations into two groups according to inoculation method. One-point inoculation was performed by coinoculation of L. mesenteroides and L. starkeyi at the ration of 10 to 1, and two-point inoculation by L. mesenteroides inoculation first and L. starkeyi inoculation after L. mesenteroides grew to the end of the log phase of growth. Two-point inoculation improved the yield of oligosaccharide by 1.5 to 20 fold more than one-point inoculation. In this process, the highest yield of oligosaccharides (48% of theoretical yield) and productivity (0.85 g/l/h) were obtained with starch as an initial substrate for L. starkeyi growth. The estimated composition of the end product consisted of 31.5% oligosaccharides, 17.6% dextran, and 46.5% mannitol.

• Journal of Microbiology and Biotechnology
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• v.3 no.2
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• pp.115-122
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• 1993

Poly(3-hydroxybutyrate)(P(3HB)) accumulation under nutrient-rich condition with various amounts of $(NH_4)_2 SO_4$ was systematically investigated. The results of the electron-microscopy and the solvent extraction showed that the P(3HB) accumulation is unavoidable even under nutrient-rich condition. This indicates that in a two-step culture of Alcaligenes eutrophus H16, the researches should be careful in interpreting the data of polyhydroxyalkanoates(PHAs) accumulation in terms of the carbon-source fed in the second step because the two-step culture product contains the P(3HB) produced under nutrient-rich condition. The polyester production capability in a two-step batch culture of A. eutrophus H16(ATCC 17699) was also investigated using various saccharides and their derivatives such as glucose, fructose, gluconic acid, glucaric acid, sorbitol, lactose, galactose, and mannose. The polyesters synthesized were characterized by 500 MHz$^{1}H-NMR$ spectroscopy, intrinsic viscosity$[\eta]$ measurement in chloroform and differential scanning calorimetry(DSC). 500 MHz $^{1}H-NMR$ analysis showed that all polyesters synthesized generally contained 1~2 mol% of 3HV. Another finding is that the glucose utilization can be increased by changing the autoclaving procedure of the substrate to enhance the P(3HB) production yield up to 46 wt% of P(3HB) in dry cells.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.207-210
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• 2000

Pseudomonas oleovorans was cultivated to produce medium chain length polyhydroxyalkanoates (MCL-PHA) fram octanoic acid and ammonium nitrate as carbon and nitrogen source, respectively, by a pH-stat fed-batch culture technique. The octanoate concentration of the culture broth was maintained below 4 g/L by feeding the mixture of octanoic acid and ammonium nitrate when the culture pH rose above high limit. The effect of the ratio of octanoic acid to ammonium nitrate (C/N ratio) in the feed on the PHA production was examined. The final cell concentrations of 62.5, 54.7, and 9.5 g/L, PHA contents of 62.9, 75.1, and 67.6% of dry cell weight, and productivities of 1.03, 0.632, and 0.161 g/L/h were obtained when the C/N ratio in the feed were 10, 20, and 100 g octanoic acid/g ammonium nitrate, respectively.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.149-152
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• 2003

This experiment was carried out to obtain the optimal liquid culture conditions for the mycelial growth and the polysaccharide production of Tricholoma matsutake. For the mycelial growth and polysaccharide production, the synthetic medium was optimized with containing glucose 40 g/L, yeast extract 30 g/L, $KH_2PO_4$ 1.5 g/L and $MgSO_4.7H_2O$ 1 g/L. The effects of agitation and aeration were investigated for the cell growth and the polysaccharide production in batch culture. The biomass and polysaccharide concentrations were 21.87 g/L at 150 rpm and 8.86 g/L at 300 rpm, respectively. And the biomass concentration and the polysaccharide production were 20.85 g/L at 0.5 vvm and 8.83 g/L at 1.5 vvm, respectively.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.326-329
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• 1992

Mucor sp. KCTC 8405P was cultivated in a jar fermentor for the production of fungal lipid containing ${\gamma}-linolenic$ acid with feeding the glucose solution periodically. The transition of the fungal growth into the mycelial phase from yeast-like growth was achieved by pH shift after the first two day of cultivation in the low pH medium and then lipid accumulation was accelerated until the seven day of cultivation, when the glucose in the culture broth was almost consumed. With the culture conditions applied in this experiment, biomass of 99.3 g/l by the dry cell weight and the total extractable lipid of 38.0 g containing 3.5 g/l ${\gamma}-linolenic$ acid were obtained.

• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.348-353
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• 1993

The optimal conditions for operating a moving-aeration bioreactor were determined as 30rpm and 150 (ml/min) of air flow rate, which can yield ca. 7.3 (l/h)of maximum mass transfer coefficient. It was also found that the agitation speed played much much important role than air input rate in oxgen transfer into the medium. $2.6{\times}10^6$ (cells/ml) and 0.6 (ml/l) of maximum cell denisty and IL-2 production were observed in batch cultivation of IL-2 producing BHK cell line. 0.53 (mM/l/h) of oxygen uptake rate was also estimated. The performance of a moving-aeration bioreactor (specific growth rate and oxygen uptake rate, etc.) was superior to other culture systems, such as cell-life and static membrane aeration bioreactors. Ii must be useful to apply this reactor to many culture processes by improving structural limitations in scaling-up the system.

• Proceedings of the Microbiological Society of Korea Conference
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• 2001.11a
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• pp.113-120
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• 2001

The production of microcystins from Microcystis aeruginosa was investigated in a P-limited continuous culture and a batch culture. The microcystin content of M aeruginosa was higher at a lower $\mu$, whereas the microcystin (MC)-producing rate was linearly proportional to $\mu$. The ratios of the MC-producing rate to the C-fixation rate were higher at a lower $\mu$. Consequently, increases in the microcystin content per dry weight along with the production of the more toxic form, MC-LR, were both observed under more P-limited conditions. The microcystin content of M. aeruginosa exhibited a high correlation with the total N content regardless of N-fixed or P-fixed culture. The microcystin concentration was investigated from spring to autumn in 1999 in the Daechung Reservoir, Korea. The dominant species in the algal blooming season was Microcystis. When the microcystin concentration exceeded about 100 ng $1^{-1}$ the ratio of particulate to dissolved total nitrogen (TN) or total phosphorus (TP) interestingly converged at a value of 0.6. The microcystin concentration was lower than 50 ng $1^{-1}$ at a particulate N:P ratio below 8, whereas the microcystin concentration varied quite substantially from 50 ng $1^{-1}$ to 250 ng $1^{-1}$ at a particulate N:P ratio> 8.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.90-100
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• 1985

The present study was designed to investigate cellular regulation of phosphate metabolism between catabolically repressed and derepressed states in yeast (Saccharomyces uvarum). The activities of various phospatases and the contents of phosphate compounds were detected according to the culture phase and various phosphate concentrations. As the results, Saccharomyces uvarum derepressed many phosphate metabolizing enzymes such as alkaline phosphatase, acid phosphatase and ATPase more than ten fold simultaneously during catabolic repression (phospgate and sugar starvation). At the same state, the amounts of orthophosphate, nucleotidic labile phosphate and acid soluble polypgosphate were increased, compared to basal levels of normally cultivated cells. $Mg^{++}-stimulated$ type among all phospatases was appeared to have most of the enzyme activity. It could be postulated that $K^+ -stimulated$ alkaline phosphatase was directly or indirectly correlated with the synthesis of acid insoluble polyphosphate $Mg^{++}-stimulated$ phosphatase with the degradation of polyphosphates. In case of cultivation in the medium supplemented with sugar and phosphate (catabolic derepression), phospgatase activities except for alkaline phosphatase were decreased rapidly through the progressive batch culture, After 12 hrs culture, at early exponential phase, the cellular accumulation of acid insoluble polyphosphate increased about 5 fold, compared to those of the starved cells. Under catabolic repression, it could be postulated that intracellular phosphate metabolism was regulated by derepressions of phosphatases. The function of polyphosphate system was shown to compensate the ATP/ADP system as phosphate donor and energy source especially during catabolic repression.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1928-1935
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• 2015

Microbial growth kinetics is often used to optimize environmental processes owing to its relation to the breakdown of substrate (contaminants). However, the quantification of bacterial populations in the environment is difficult owing to the challenges of monitoring a specific bacterial population within a diverse microbial community. Conventional methods are unable to detect and quantify the growth of individual strains separately in the mixed culture reactor. This work describes a novel quantitative PCR (qPCR)-based genomic approach to quantify each species in mixed culture and interpret its growth kinetics in the mixed system. Batch experiments were performed for both single and dual cultures of Pseudomonas putida and Escherichia coli K12 to obtain Monod kinetic parameters (μ_max and K_s). The growth curves and kinetics obtained by conventional methods (i.e., dry weight measurement and absorbance reading) were compared with that obtained by qPCR assay. We anticipate that the adoption of this qPCR-based genomic assay can contribute significantly to traditional microbial kinetics, modeling practice, and the operation of bioreactors, where handling of complex mixed cultures is required.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.5
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• pp.341-346
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• 2001

For the purpose of mass producing Monascus red pigments optimum medium composition and environmental conditions were investigated in submerged flask cultures. The optimum carbon and nitrogen sources were determined to be 30g/L of glucose and 1.5 g/L of monosodium glutamate (MSG). Of the three metals examined, Fe$\^$2+/ showed the strongest stimulatory effect on pigment production and some stimulatory effect was also found in Mn$\^$2+/. Optimum pH and agitation speed were determined to be 6.5 and 700 rpm, respectively. Under the optimum culture conditions batch fermentation showed that the maximum biomass yield and specific productivity of red pigments were 0.20 g DCW/g glucose and, 32.5 OD$\sub$500/g DCW$\^$-1/h$\^$-1/, respectively.