• Korean Journal of Food Science and Technology
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• v.15 no.1
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• pp.51-55
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• 1983

It was investigated under several cultural conditions to produce biomass directly from starch by an strictly aerobic and amylolytic yeast, Sporobolomyces holsaticus FRI Y-5. Its optimal temperature and initial pH of medium for growth were $23^{\circ}C$ and 6.9, respectively. Activation energy, Ea, for growth was calculated to be 17.33 Kcal/mole from the Arrhenius relationship. When each of 13 nitrogen sources was added to the basal medium, $(NH_2)_2CO$ had the best effect, on which concentration of cell after 3 day incubation was 10.6 g/l and cell yield was 0.451. The yeast growth was affected by $MgSO_4,\;K_2SO_4\;and\;ZnSO_4$ as a mineral source and was best on the medium containing all of them. The addition of yeast extract (5g/l) could enhance the production of biomass and cell yield to 77% and 32%, respectively.

• Journal of Life Science
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• v.14 no.5
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• pp.868-873
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• 2004

The efficient fermentative production of L-threonine fermentation was achieved by using Escherichia coli MT201, transformed a plasmid carrying pyruvate carboxylase gene. It is an attempt to supply oxaloacetate to the L-threonine biosynthetic pathway. In order to improve the L-threonine productivity of E. coli MT201, a plasmid pPYC which is an expression vector of the pyruvate carboxylase gene of Coryne-bacterium glutamicum, was introduced. When E. coli MT/pPYC was incubated with medium containing only glucose as a carbon source, both the cell growth and L-threonine production were reduced, compared to the results from fermentation of E. coli MT201. In order to circumvent this effect, we attempted the addition of a mixed carbon source, composed of glucose and sodium citrate at a ratio of 1.5:3.5. It was shown that L-threonine production and cell growth (OD660) with E. coli MT/pPYC reached up to 75.7 g/l and 48, respectively, at incubation for 75 hr under fed-batch fermentation conditions. It is assumed that overproduction of L-threonine by anaplerotic pathway leads unbalance of TCA cycle and sodium citrate might playa role to recover normal TCA cycle.

• Korean Journal of Agricultural Science
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• v.4 no.1
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• pp.105-111
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• 1977

Inhibitory effect of sugars on lipase production by Trichosporon cutaneum was observed in the previous study (Kim, 1972), and inhibition was distinctive by the addition of glucose, fructose, mannose, xylose and arabinose to the soybean meal medium among various carbon sources. These experiments were carried out to study the effect of sugars on cell growth and lipase production by the strain using the soybean extracts liquid medium under a shaking culture system. Changes in color and pH of the medium were caused by heat sterilization when various sugars were added. To elucidate the possible effect of these coloring matters on lipase production and cell growth: changes in pH of the culture, cell concentration and level of the enzyme activities were determined when the culture was grown for 48 hours at $30^{\circ}C$ on a reciprocal shaker. The results obtained were as follows: 1. Density of brownish color which formed during heat sterilization was varied with the variety of sugar used, ie, strong in pentose such as xylose: weak in hexose such as galactose, mannose, glucose: very weak in disaccharide such as maltose, sucrose. When the color density was stronger, decrease in pH after sterilization was marked. 2. Cell growth and lipase production was not so effect by the coloring matters as by sugars. 3. The more the cell mass of the culture, the lower the level of lipase production in the culture supernatant. 4. Among the sugars which caused the distinctive inhibition of lipase production, a slight relief of inhibition was noticed by the addition of xylose, whereas the cell growth was repressed. 5. When cell growth was better, decrease in pH of the medium was greater during cultivation.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1978.10a
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• pp.208.1-208
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• 1978

Phenol 성 물질이 함유된 산업폐수의 처리와 phenol을 탄소원으로 하는 균체를 이용할 목적으로 공업폐수의 오이로부터 phenol 자화능이 우수한 효모 균주를 선택하여 이 균의 생육에 미치는 환경요인을 조사하였다. 초발 pH 3.5~4.5에서 $35^{\circ}C$ 경우 자화능이 가장 좋았으며 $HgC1_2$ phenylhydrazin $10^{-3}$M 농도에서 완전히 자화능을 잃었다. 배양기 중의 질소원으로 $KNO_3,$ $(NH_2)_2CO가$ 가장 좋았으며 yeast extract 0.01% 첨가하므로써 가장높은 발육효과를 보았다. Phenol을 연속적으로 90시간까지 5회 feeding하며 계속적인 균체증식과 phenol 소모를 보았으며 한편 본균이 catechol, resorcinol도 자화할 수 있다는 점도 알았다.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.262-267
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• 2006

Inhibitory effects of fungal metabolites isolated from foodstuffs on growth of human cancer cell lines were evaluated. Isolated strains were divided into four classes based on color (aerial, reverse), shape, and growth speed. Fungal metabolites extracted with ethyl acetate were investigated for their growth inhibition on six kinds of human cancer cells by MTT assay. Ethyl acetate extract showed high growth inhibition against all cancer cells tested, with D4 exhibiting the strongest growth inhibition effects against Kato III, AGS, Hepa1c1c7, and MDA-MB-231 cancer cells. These results suggest ethyl acetate extract from fungal metabolites as effective natural cancer therapeutic material.

• Korean Journal of Food Science and Technology
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• v.6 no.4
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• pp.231-240
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• 1974

The growth of a mixed yeast culture consisting of Canda tropicalis var. KIST 76 and Tricosporon cutaneum KIST 76-H was compared with that of pure cultures under pilot plant conditions. The mixed culture was judged stable based on the nearly constant ratio of the two organisms at the completion of fermentation. We obtained higher cell yields, protein content and productivity in the mixed culture on n-paraffin than the pure culture of C. tropicalis var. KIST 76. T. cutaneum KIST 76-H did not grow on n-paraffin medium. With the batch cultivation of mixed organisms on n-paraffin, the specific growth rates during the exponential growth phase were 0.24-0.33 $hr^{-1};$ cell yields were 96-106% and productivities were 2.9-3.6g/l. hr. The cells obtained contained 55-58% crude protein and 5.5-6.3% lipid. The critical value of dissolved oxygen concentration Ccrit. and saturation constant, km, are approximately 1.5 ppm and 0.228 ppm respectively. Also we established the optimal conditions for the mixed culture in batch fermentation.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.221-225
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• 1992

The possibility of using Chinese cabbage juice as a substrate for the production of Candida utilis cell mass was explored. Dry cell weight production and cell yield coefficient were 1.35-1.45 g/100 ml undiluted juice and 47-50%, respectively, when C. utilis was grown by shake flask culture at $30^{\circ}C$ for 24 hr on more than three-fold diluted Chinese cabbage juice to make the final sugar content be equal to or less than 1.0%. Supplementation of glucose(2%), $KH_2PO_4(0.2%)$ and $(NH_4)_2SO_4(0.2%)$ to three-fold diluted Chinese cabbage juice did not enhance the dry cell weight yield or the protein content of the yeast cell, while supplementation of yeast extract(0.2%) and peptone(0.2%) increased dry cell weight production and protein content but not as much as the amount of each nutrient added. It was found that Chinese cabbage juice was an excellent substrate for the cultivation of C. utilis.

• Korean Journal of Food Science and Technology
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• v.28 no.5
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• pp.970-973
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• 1996

Effect of cell density on the xylitol production from xylose by Candida parapsilosis KFCC 10875 was investigated. The concentrated cells were obtained by centrifugation of culture broth. The xylitol production rate was maximum at the cell concentration of 20 g/l and the specific xylitol production rate decreased when the cell concentration was increased due to oxygen limitation. Effect of the initial concentration of xylose on the xylitol production was also examined using the concentrated cells of 20 g/l. The xylitol production rate, specific xylitol production rate, and xylitol yield from xylose were maximum at 170 g/l xylose. Above 170 g/l xylose, the xylitol production rate was remarkably decreased. The concentrated cells could also be obtained by adjusting the dissolved oxygen (DO) during fermentation. The rapid accumulation of cells up to 20 g/l was achieved by maintaining an increased level of DO during the exponential growth phase and then, for the efficient xylitol production, the DO was changed to a low level in the range of 0.7-1.5%. A fed-batch fermentation of xylose by adjusting the DO level was carried out in a fermentor and the final xylitol concentration of 140 g/l from xylose of 200 g/l could be obtained for 56 h fermentation.

• KSBB Journal
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• v.10 no.2
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• pp.176-182
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• 1995

The environmental and physiological factors affecting the production of exopolysaccharide (Methylan) and Poly-${\beta}$-hydroxybutyrate(PHB) by Methylobacterium organophilum were investigated. The maximum PHB content was obtained at $38^{\circ}C$ whereas maximum polysaccharide concentration was $3.54g/\ell$ at $30^{\circ}C$. Optimum pH was pH 7-8 for PHB production and pH 6-7 for polysaccharide production, respectively. Under the condition of $Mo^{2+}, Mg^{2+} or Mn^{2+}$ limitation with nitrogenlimitation, the PHB accumulation was increased, whereas the polysaccharide production was decreased as compared with that of solenitrogenlimitation. Under the condition of sole K+ limitation, cell growth was significantly inhibited and no polysaccharide was produced. However, the PHB content was as high as 60% of dry cell weight. Effect of C/N ratios (methanol/ammonium) in the feeding solution was examined for the simultaneous production of polysaccharide and PHB. The higher ratio of C/N showed the lower cell growth, higher content of PHB in cells, and higher yield of polysaccharide.

• KSBB Journal
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• v.4 no.2
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• pp.191-196
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• 1989

Functional relationship between the Fermentation characteristics of Functional relationship between the Fermentation characteristics of S. cerevisiae SIV-89 and the fermentation time was investigated. According to the increase in the initial sugar cone. from 50g/L to 80 g/L, maximum specific growth rate and maximum specific alcohol production rate were increased until 0.35 and 1.98. But the two values were decreased with increase of initial sugar cone. in the region of more that 80 g/L. Maximum alcohol yield and biomass yield were 0.45 and 0.15 respectively. However those vlaue were found to be reduced with the argument of initial sugar concentration. Sugar conversion was decreased with sugar concentration. When the sugar concentration was more than 190 g/L, the conversion was dropped below 70%. The increase of alcohol concentration in the fermentation broth induced the phenomenon of decline of metabolism. In case of more than 80 g/L of alcohol conc., biomass growth and alcohol production were completely stopped regardless of remaining sugar concentration.