• Microbiology and Biotechnology Letters
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• v.22 no.4
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• pp.333-339
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• 1994

In order to screen microorganisms producing phospholipase D (PLD) [EC 3.1.4.4], culture broths of about 900 strains of soil bacteria were subjected to examine for the PLD activity. When the hydrolytic activity of PLD (H-activity) in the supernatant was determined, 64 strains produced PLD more than 0.3 unit/ml and all of them were actinomycetes. Among 26 culture broths tested, 6 ones had transphosphatidylation activity (T-activity) of 30~68%. When the strains except one were cultivated on 3 different media at 30$\circ$C for 3 days under aerobic condition, strain # 1090 on medium B (yeast extract 1%, peptone 1%, glucose 1.5%, glycerol 1%, CaCO$_{3}$ 0.4%, and pH 7.2) produced PLD with much higher H- and T-activity, which were 8.3 units/ml and 76.3%, respectively. Subsequently, time course of PLD production of the strain # 1090 during cultivation with aeration of 1 v/v/m and agitation of 400 rpm at 30$\circ$C for 5 days on medium B in jar fermentor was investigated. H-activty of PLD reached almost maximum (about 9 units/ml) after 32 hours and maximal T-activity was found to be about 80%.

• Korean Journal of Agricultural Science
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• v.3 no.2
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• pp.225-234
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• 1976

To elucidate ${\beta}$-glucosidase formation on various carbon scurces by cellulolytic bact-eia, Cellulomonas sp. CS1-1, the strain was grown on Nutrient Yeast Broth, carboxymethyl cellulose, avicel and cellobiose using a Ouickfit FVIL fermentor operated in batch, and the growth characteristics on those substrates and ${\beta}$-glucosidase distribution of extra and intracellular enzyme components were studied. The results were: 1) ${\beta}$-glucosidase was always intracellular, and was formed under all growth conditions tested, ii) but levels of relative activities were higher when the culture was grown on cellobiose and on avicel, iii) the relative activities were always maximum during the growth phase of the organism irrespective of the substrate used.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.6
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• pp.357-361
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• 2002

Continuous production of lactic acid from glucose by Lactobacillus rhamnosus with cell recycling using an acoustic cell settler was carried out. The performance of the system, such as the concentration of cell and product were compared with the control experiment without recycling. The acoustic settler showed cell separation efficiency of 67% during the continuous operation and the cell concentration in the fermentor with recycle exceeded that of the control by 29%. Com-pared with the control, tactic acid production was increased by 40%, while glucose consumption was only increased by 8%. The higher value of lactic acid production to substrate consumption (Yp/s, product yield coefficient) achieved by cell recycling is interpreted to indicate that the recycled cell mass consumes less substrate to produce the same amount of product than the control Within system environmental changes due to the longer mean cell residence time induced the cells maintaining the metabolic pathways to produce Less by-Product but more product, lactic acid.

• KSBB Journal
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• v.4 no.2
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• pp.118-122
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• 1989

From the on-line mass spectrometric analyese of the exhaust gaseous composition of fermentor and the material balance equations for oxygen and carbon dioxide, oxygen uptake rate (OUR) and carbon dioxide evolution rate (CER) were calculate using a personal computer (IBM PC-AT) interfaced to a quadrupole mass spectromter. The calculate OUR and CER were used for the indirect estimation of cell and substrate concentrations during the batch culture of Candida utilis. For the estimation of sustrate concentration, the yield model of Pirt was applied. It was found that the cell and substrate (glucose) concentration could be ssatisfactorily estimataed and the results showed the more accurate estimations of both fermentation state variables when OUR data were used than CER data.

• KSBB Journal
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• v.10 no.2
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• pp.113-118
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• 1995

Investigation and optimization of culturing conditions were performed for the production of microbial surfactant, O-acid (precursor of S-acid) using Pencilium spiculisporum. Glucose and ammonium nitrate were found to be the most effective carbon and nitrogen sources, respectively. Supplementation of medium with trace elements, such as $CaCl_2 and FeSO_4$, increased the O-acid production by 20% and maintenance of the dissolved oxygen tension near saturation increased 40% of the O-acid productivity. Also 60% increase in the O-acid production was observed by maintaining the glucose concentration near 50%g/l by feeding glucose during the cultivation.

• KSBB Journal
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• v.9 no.1
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• pp.8-15
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• 1994

The research has been carried out to optimize a recombinant S. cerevisine fermentation process for the production of an anticoagulant hirudin. The structural gene coding for hirudin was combined with the GAL10 promoter for controlled expression, the MFal signal sequence for hirudin secretion, and the GAL7 terminator for transcriptional termination. Growth medium composition and environmental conditions were optimized for maximizing cell growth and final hirudin concentration. The optimized conditions included yeast extract 40g/$\ell$, casamino acid 5g/$\ell$, g1ucose 20g/$\ell$, galactose 30g/$\ell$, DO 50% and temperature $30^{\circ}C$. These conditions yielded the specific cell growth rate of $0.13hr^{-1}$, the final cell density of 30g cell/$\ell$ and the final hirudin concentration of 64mg/$\ell$ in the batch fermentation with a 2.5$\ell$ jar fermentor.

• KSBB Journal
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• v.28 no.5
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• pp.282-286
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• 2013

The seaweed, Gelidium amansii, was fermented to produce bioethanol. Optimal pretreatment condition was determined as 94 mM $H_2SO_4$ and 8% (w/v) seaweed slurry at $121^{\circ}C$ for 60 min. The mono sugars of 40.4 g/L with 67% of conversion from total carbohydrate of 60.6 g/L with 80 g dw/L G. amansii slurry were obtained by thermal acid hydrolysis pretreatment and enzymatic saccharification. G. amansii hydrolysate was used as the substrate for ethanol production by Kluyveromyces marxianus KCTC 7150 and Candida tropicalis KCTC 7212 using 5L fermentor. The ethanol productions by K. marxianus KCTC 7150 and C. tropicalis KCTC 7212 were 17.8 g/L with $Y_{EtOH}$ of 0.48 at 120 h and 19.3 g/L with $Y_{EtOH}$ of 0.50 at 120 h, respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.1
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• pp.1-6
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• 2000

For the rapid selection of higher recombinant hirudin producing strain in a methylotrophic yeast Hansenula polymorpha, a multiple gene integration and dose-dependent selection vector, based on a telomere-associated ARS and a bacterial aminoglycoside 3-phosphotransferase (aph) gene, was adopted. Two hirudin expression cassettes (HV1 and HV2) were constructed using the MOX promoter of H. polymorpha and the mating factor $\alpha$ secretion signal of S. cerevisiae. Multiple integrants of a transforming vector containing hirudin expression cassettes were easily selected by using an antibiotic, G418. Hirudin expression level and integrated plasmid copy number of the tested transformants increased with increasing the concentration of G418 used for selection. The expression level of HV1 was consistently higher than that of HV2 under the similar conditions, suggesting that the gene context might be quite important for the high-level gene expression in H. polymorpha. The highest hirudin producing strain selected in this study produced over 96 mg/L of biologically active hirudin in a 500-mL flask and 165 mg/L in a 5-L fermentor.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.181-185
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• 2000

A marine microorganism, strain 96CJ10356 produced exopolysaccharide, designated as EPS-R. To optimize culmize culture conditions for the production of EPS-R, carbon and nitrogen sources, mineral salts, temperature, and pH were exmined. From this study, STN medium for the production of EPS-R was suggested as follows; sucrose 20g, typtone 10g, NaCl 10g, MgSO45g, CaCl21g, KH2PO4 76mg, K2HPO4 83mg, FeCl2 5mg, MnCl2 1mg, NaMoO4 1mg, and ZnCl2 1mg per liter at pH 7.0. About 9.23g/L of EPS-R was obtained from STN medium after cultivation for 120h at $25^{\circ}C$ in a 5-liter jar fermentor with an aearation rate of 0.17 vvm. Apparent viscosity and flocculation activity of the culture broth were increased with the production of EPS-R and the maximal values were 415 cP and 1400 unit/mL against 0.5% activated carbon, respectively.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.346-351
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• 1995

To produce ethanol from Jerusalem artichoke powder efficiently, Kluyveromyces marxianus F043 cells were encapsulated in 2% sodium alginate and were cultured in a countinuous reactor to investigate the fermentation properties. Immobilized K. marxianus F043 cells were activated for 48 hours in a fermentor for continuous ethanol production. The culture in a CSTR using a Jerusalem artichoke substrate treated with 2% cellulase showed a decrease in ethanol concentration and an increase in residual saccharide concentration with a increasing dilution rate. Optimum conditions for high ethanol productivity and low residual saccharide output were clarified to be given at a dilution rate of 0.2 h$^{-1}$ and a Jerusalem artichoke medium concentration of 75 g/l. Ethanol productivity of 3.1 g/l-h and saccharide utilization of 62.6% were obtained under the optimum condition. When the fermentation was performed for 3 weeks under these conditions, the effluent medium showed stable ethanol concentrations of 16.3 - 17.9 g/l and viable cells of 6.60-7.16 log cells/ml without contamination. Trace amounts of methyl, n-propyl, iso-butyl, isoamyl alcohols besides ethanol were detected.