• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.329-334
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• 1992

For the photoproduction of molecular hydrogen by photosynthetic bacteria in outdoor conditions, we constructed automatically controlled semi-continuous culture system. When the amount of hydrogen gas produced can be measured by a gas meter with a pulse generator, the same amount of substrate consumed for hydrogen production could be supplied by micro pump related with timers. Using the apparatus, we examined hydrogen production with immobilized cells of Rhodopseudomonas sPhaeroides B6 in outdoor conditions. In spite of severe fluctuation of weather and illumination, the culture was maintained under good control with regard to hydrogen productivity. It was possible to automate the semi-continuous outdoor culture of photosynthetic bacteria for hydrogen production.

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.781-787
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• 2014

2-Ketogluconic acid production by Klebsiella pneumoniae is a pH-dependent process, strictly proceeding under acidic conditions. Unfortunately, cell growth is inhibited by acidic conditions, resulting in low productivity of 2-ketogluconic acid. To overcome this deficiency, a two-stage fermentation strategy was exploited in the current study. During the first stage, the culture was maintained at neutral pH, favoring cell growth. During the second stage, the culture pH was switched to acidic conditions favoring 2-ketogluconic acid accumulation. Culture parameters, including switching time, dissolved oxygen levels, pH, and temperature were optimized for the fed-batch fermentation. Characteristics of glucose dehydrogenase and gluconate dehydrogenase were revealed in vitro, and the optimal pHs of the two enzymes coincided with the optimum culture pH. Under optimum conditions, a total of 186 g/l 2-ketogluconic acid was produced at 26 h, and the conversion ratio was 0.98 mol/mol. This fermentation strategy has successfully overcome the mismatch between optimum parameters required for cell growth and 2-ketogluconic acid accumulation, and this result has the highest productivity and conversion ratio of 2-ketogluconic and produced by microorganism.

• KSBB Journal
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• v.13 no.1
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• pp.58-64
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• 1998

An extracellular lipid-producing strain, Rhodotorula glutinis K-501, was isolated from soil. The extracellular lipid produced by the cell was found to have good and stable emulsifying activity. Factors affecting the extracellular lipid production were studied to optimize culture conditions for maximum production. Sucrose and ammonium sulfate were selected as best carbon and nitrogen sources, respectively because they gave the highest concentration of product. The optimum C/N ratio was 50. Optimum concentrations of $KH_2PO_4,\; Na_2HPO_4, \;and\; CaCl_2 $were 3.5, 1.0, 0.75, and 0.1g/L, respectively. The optimum temperature and initial pH were determined as $22^{\circ}C$ and 7.0, respectively. When the batch culture was conducted with a sucrose concentration of 60g/L under the optimized conditions, extracellular lipid was produced to a concentration of 8.1g/L with a high production yield of 51.9% based on dry cell weight.

• Food Science and Preservation
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• v.13 no.2
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• pp.192-197
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• 2006

The optimum cultural conditions for production of yellow pigment by Monascus purpureus MMK2 were investigated in liquid culture. Monascus purpureus MMK2 was shown to give the maximum production of yellow pigment in the medium containing of 3.0% wheat flour, 0.15% $NaNO_3$, 0.25% $Na_2HPO_4\;12H_2O\;and\;0.15%\;MgSO_4\;7H_2O$. The optimal culture conditions for temperature and initial pH were $30^{\circ}C$ and 6.5, respectively. The yellow pigment production reached a maximum level at the 7th day of cultivation.

• The Korean Journal of Food And Nutrition
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• v.23 no.1
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• pp.70-75
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• 2010

This study was conducted to determine the influence of culture conditions such as temperature, time, water content, koji-thickness and agitation on the production of organic acid by Rhizopus sp. ZB9 isolated from Korean Nuruk during the preparation of rice koji, which is used in brewing the Korean rice wines, Takju and Yakju. Rice koji was made under different culture conditions, and the acidity of each koji was tested. The temperature range suitable for the production of organic acid was $28{\sim}32^{\circ}C$, and 36~48 hours of cultivation at that temperature range seemed to produce the optimum results. The production of organic acid increased in proportion to the increase in water content of steamed rice from 25% to 60%. An increase in koji-thickness induced no adverse effects on the production of organic acid, and agitation-work during cultivation showed very beneficial effects.

• KSBB Journal
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• v.19 no.1
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• pp.78-82
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• 2004

Experiments were carried out to select an organic nitrogen source and optimize the culture conditions for the production of arachidonic acid by Mortierella alpina DSA-12. Corn steep powder(CSP) was selected as an organic nitrogen source based on arachidonic acid production and raw material price. The optimum C/N ratio was in the range of 15 to 17 with the medium containing glucose as carbon source and CSP as nitrogen source. The optimum culture conditions for arachidonic acid production showed 500 rpm agitation and 25$^{\circ}C$ culture temperature at 0.5 vvm aeration. Under the optimum conditions, the concentration of cell, total lipid and arachidonic acid were 21.8 g/L, 10.2 g/L and 3.70 g/L, respectively, from 50 g/L glucose and 18 g/L CSP. In the 500 L fermenter with 0.5 vvm aeration and 200 rpm agitation, the concentration of cell, total lipid and arachidonic acid were 19.8 g/L, 9.1 g/L and 3.67 g/L, respectively, from 50 g/L glucose and 18 g/L CSP. This result showed that an arachidonic acid production could be possible with a bench-scale fermenter using corn steep powder as a nitrogen source.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.408-413
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• 2006

We assessed the ability of a Pseudonocardia sp. from soil samples to bioconvert vitamin $D_3$. The optimal culture conditions for the bioconversion of vitamin $D_3$ to active $1{\alpha}$,25-dihydroxyvitamin $D_3$ were investigated by varying the carbon and nitrogen sources, the metal salt concentrations, the initial pH, and the temperature. Microbial transformations were carried out with the addition of vitamin $D_3$ dissolved in ethanol. They were sampled by extraction with methanol-dichloromethane and the samples were examined by HPLC. Optimum culture conditions were found to be 0.4% yeast extract, 1% glucose, 3% starch, 1% fish meal, 0.2% NaCl, 0.01% $K_2HPO_4$, 0.2% $CaCO_3$, 0.01% NaF, and pH 7.0 at $28^{\circ}C$. The optimal timing of the addition of vitamin $D_3$ for the production of calcitriol by Pseudonocardia autotrophica ID9302 was concurrent with the inoculation of seed culture broth. Maximum calcitriol productivity and the yield of bioconversion reached a value of 10.4mg/L and 10.4% respectively on the 7th day in a 75L fementer jar under the above conditions.

• The Korean Journal of Food And Nutrition
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• v.23 no.3
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• pp.399-404
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• 2010

This study was conducted to determine the influence of culture conditions such as temperature, time, water content, koji-thickness, and agitation on the production of protease by Rhizopus sp. ZB9, isolated from Korean Nuruk, during the preparation of rice koji, which is used in brewing the Korean rice wines, Takju and Yakju. Rice koji was made under different culture conditions, and the proteolytic activity of each koji was tested. The temperature range suitable for the production of protease was $28~32^{\circ}C$. Based on the protease and color, 60 hours of cultivation at $28^{\circ}C$ was shown to produce optimum results. The production of protease increased in proportion to the increase in water content of steamed rice from 25% to 35%. An increase in koji-thickness induced no adverse effects on the production of protease, and agitation during cultivation showed beneficial effects.

• Journal of Ginseng Research
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• v.24 no.2
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• pp.58-63
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• 2000

To develop the production of ginseng root using plant tissue culture technology, submerged culture conditions were optimized by means of the fractional factorial design with 4 factors and 3 levels by a RSM computer program. The ginseng (Panax ginseng C. A. Meyer) roots induced by plant growth regulators were cultured on SH medium and the effects of various pH of medium, sucrose concentration, nitrogen concentration and phosphate concentration on fresh weight of the ginseng root were investigated. The fresh weight of ginseng root increased with a decrease in nitrogen concentration and fresh weight of ginseng root varied from 1.00 to 2.33g under various conditions. The optimum pH of medium and sucrose concentration determined by a partial differentiation of the model equation, nitrogen and phosphate concentration were pH 5.6, sucrose 3.8%, nitrogen 50 mg/L and phosphate 80.7 mg/L, respectively. Under these conditions, the predicted growth of ginseng root was estimated to be 2.36g.

• Journal of Microbiology
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• v.34 no.2
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• pp.179-183
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• 1996

Streptoccus Pneumoniae (pneumococcus), the most common cause of bacterial pneumonia, has an ample polysaccharide (PS) capsule that is highly antigenic and is the source of PS vaccine. This investigation was undertaken to optimize the culture conditions for the production of capsulard PS by type 1 pneumococcus. Among several culture media, brain heart infusion (BHI) and Casitone based media were found to support luxuriant growth of pneumococcus type 1 at the same level. Because BHI medium is rather expensive and more complex than the Casitone based media, the Casitone based media was uwed to study optimization of the culture condition. The phase of growth which accomodated maximum PS production was logarithmic phase. Concentrations of glucose greater than 0.2% did not ehnahce growth or PS production. Substitution of netrogen sources with other resources or supplementation of various concentrations of metal ion (with the exception of calcium ion) had adverse affects on growth and PS production. On the other hand, low level aeration was beneficial for increased PS production. Addition of 3 mg/1 concentration of methionine, phenylalanine, and threonine were found to enhance growth and PS production. The synerigistic effect of all the favorable conditions observed in pneumococcal growth assays provided a two-fold cummulative increase in capsular PS production.