• KSBB Journal
• /
• v.20 no.1 s.90
• /
• pp.26-33
• /
• 2005

The effects of carbon sources for exopolysaccharide production during batch cultivation of an Enterobacter sp. isolated from the composter were investigated. The highest amount of exopolysaccharide was obtained when lactose was used as carbon source. Lactose in medium was converted into glucose and galactose. Glucose was metabolized fast and was completely consumed, but about $20\%$ of lactose was accumulated as galactose. On the other hand, enzyme activity was about $350\~450$ unit with the increase of lactose concentration. Thus, it was considered that the exopolysaccharide might be produced in the course of that lactose was hydrolyzed into glucose and galactose by $\beta-galactosidase$ with respect to that enzyme activity on lactose hydrolysis was accorded to the exopolysaccharide production. When glucose and galactose were added to lactose medium, respectively, it could be considered that glucose was as a repressor and galactose was as a inducer for $\beta-galactosidase$ synthesis even though the mechanisms were not elucidated. The increase of lactose concentration was almost ineffective to the specific growth rate $(0.133\~0.151\;hr^[-1})$ but showed the difference in the biomass content. The higher carbon source concentration, the more residual sugar remained. It was assumed that the optimum lactose concentration for exopolysaccharide production was $30\~70g/L.$ On the other hand, it was considered that the nitrogen acted as growth limiting nutrients to the cell growth. In the cases of 30 and 70 g/L of the fixed carbon concentrations, the increase of the nitrogen sources concentration caused a remarkable increase within the range of $0.059\~0.225\;hr^{-1}$ and $0.141\~0.237hr^{-1}$ of the specific growth rate, respectively, while there was no significant difference in biomass.

• The Korean Journal of Mycology
• /
• v.40 no.4
• /
• pp.235-243
• /
• 2012

We studied the effect of fermented Rhus verniciflua stem bark (FRVSB) extract (used in herbal med-icine by Koreans) on the microbial growth and enzyme activity of 12 soybean-fermenting microorganisms, including Bacillus spp., lactic acid bacteria, yeast, and other harmful bacteria. The ethanol and methanol extracts of FRVSB inhibited the growth of Bacillus subtilis, Bacillus licheniformis, Bacillus cereus, and Zygosaccharomyces rouxii, and in the disk diffusion assay, their inhibition zone diameters were 11.06-12.23, 12.32-18.38, 11.47-11.84, and 13.59-14.21 mm, respectively. The water extract did not show any inhibitory effect. In fact, the water extract addition enhanced the growth of B. subtilis and B. licheniformis by 1.3-4.5 fold and that of B. cereus by 1.2-1.4 fold. However, the water extract did not affect the growth of Lactobacillus plantarum, Lactobacillus mesenteroides, Saccharomyces cer-evisiae, and Escherichia coli. The addition of water extract increased the amylase and protease activity of B. subtilis and B. licheniformis.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1976.10a
• /
• pp.188.1-188
• /
• 1976

주유소, 공장주변의 하수 및 토양으로부터 Methanol 자화성 효모 7주를 분리하고 그중 생육이 왕성한 균주 2주에 대하여 동정을 행한즉 양주, 모두 Candida속에 속하는 것으로 추정되었다. 양주는 모두 ethanol 자화성을 가지고 생육에는 Biotin을 요구하였다. 배양특성은 최적온도 $28^{\circ}C,$ 최적 pH4~5이고 methanol 농도 1% v/v에서 증식이 양호하였고, 균체수율은 대소비 methanol에 대하여 30~40%에 달하였다.

• Microbiology and Biotechnology Letters
• /
• v.26 no.5
• /
• pp.406-412
• /
• 1998

The endoglucanase gene, egl6, of Trichoderma sp. was connected with the yeast ADH1 promoter, and the resultant plasmid, pVT-C4, was introduced into three S. cerevisiae host strains (YNN27, 2805, and SEY2102). Among each 80 transformants, the cell growth and expression level of endoglucanase were compared in test-tube cultivation, and three respective transformants for each host cells showing the highest expression level and cell growth were selected. When three recombinant yeast cells were batchwise cultivated for 48 hr in flask, the total activities of endoglucanase expressed were about 1140 unit/l with 2805/pVT-C4, 1020 unit/l with SEY2102/pVT-C4, and 590 unit/l with YNN27/pVT-C4. Irrespective of host strain, about 80% of the expressed endoglucanase was detected in the extracellular medium. In addition, it was also found that the recombinant enzyme was secreted into the culture medium as two major forms of lightly and heavily glycosylated proteins.

• Korean Journal of Food Science and Technology
• /
• v.30 no.5
• /
• pp.1209-1213
• /
• 1998

The gamma-radiation sensitivity of four kinds of Escherichia coli O157:H7 was investigated in frozen cells $(-18^{\circ}C)$ with 0.1 M phosphate buffer and inoculated cells in beef. The maximum populations were observed at 12 hr when E. coli O157:H7 was incubated in the tryptic soy broth at $37^{\circ}C$. In the case of the frozen cells at logarithmic phase, the $D_{10}$ and $12D_{10}$ values of four kinds of E. coli O157:H7 were $0.09{\sim}0.15\;kGy$ and $1.08{\sim}1.80\;kGy$, and inactivation factors were $13.33{\sim}22.22$ and $20.00{\sim}33.33$ at radiation doses of 2 and 3 kGy, respectively. The radiosensitivity of inoculated E. coli O157:H7 in beef showed the $D_{10}$ value of $0.30{\sim}0.47\;kGy$, the $12D_{10}$ value of $3.60{\sim}5.64\;kGy$, and inactivation factor of $4.26{\sim}10.00$. The radiosensitivity of the frozen cells was higher than that of the inoculated E. coli O157:H7 in beef. Gamma irradiation at doses within the range of 1.5 to 3 kGy is considered to be an effective method to control E. coli O157:H7 in beef.

• Korean Journal of Food Science and Technology
• /
• v.29 no.6
• /
• pp.1236-1240
• /
• 1997

The crude extract of Morus alba Linne bark which showed strong antimicrobial activity on Listeria monocytogenes was fractionated by some solvents and applied column chromatography for purification of active component. By silica gel column chromatography, active fraction (F-5') was purely isolated and confirmed their strong bactericidal effect on Listeria monocytogenes tested at level of 100 and 300 ppm in tryptic soy broth. The cell wall observed by SEM was abnormal after treatment of F-5'.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.28 no.1
• /
• pp.186-201
• /
• 2002

Fructan(Levan)은 식물체 및 미생물에서 발견되는 탄수화물로 이는 과당(fructose)이 $\beta$-2, 6 결합으로 연결되어 있는 polysaccaride 이다. 본 연구에서는 Fructan을 생성하는 미생물(Zymomonas mobilis)과 10% sucrose(기질), 1-2% 효모 추출물을 주성분으로 하는 배지를 사용하여 30-37$^{\circ}C$, pH 5.0-7.0에서 20-24시간 동안 배양한후 원심분리하여 균체를 제거하고 3배량의 알코올을 가하여 침전, 건조하여 얻은 Fructan의 화장품 원료로서의 가능성을 조사하였다. 보습효과에 있어서는 Hyaluronic acid와 유사하였으며, keratinocyte에 대한 세포증식 효과를 나타내었다. 또한 3-D culture에 의해 구축된 생인공 피부내에 0.05%의 sodium lauryl sulfate (SLS)를 사용하여 피부자극에 의한 초기 염증 반응을 유도한후 0.01mg/m1, 0.05mg/m1의 Fructan을 각각 처리하였을 때, SLS만을 처리한 생인공피부와 비교하여 세포증식효능을 보였고, SLS 자극물질로 유도된 전염증성 조절인자인 interleukin-l$\alpha$(IL-l$\alpha$)의 분비량을 조사 하였을때 0.01mg/ml, 0.05mg/ml의 Fructan을 처리한 생인공피부의 IL-l$\alpha$ 양이 Fructan을 처리하지 않은 것보다 상대적으로 감소하였다. 이러한 결과로 Fructan이 생인공 피부내 피부 세포의 증식효과를 나타낼 뿐만 아니라, 또한 피부자극물질에 의한 염증반응에 대해 자극완화효능이 있음을 알 수 있었다. 섬유아세포 및 동물을 이용한 안전성 시험에서도 독성이 없는 안전한 원료로 평가되었다.

• Microbiology and Biotechnology Letters
• /
• v.15 no.6
• /
• pp.396-401
• /
• 1987

Protein productivities of a cloned gene ($\beta$-galactosidase) and the cultural performances of two recombinant Escherichia coli strains, which use different host-vector systems, were studied. E. coli JM109/pTBG10 strain which carries Tac promoter had higher protein productivity than E. coli MH3000 (pRKc1857)/pASI(lacZ) strain which carries pL promoter. Induction of protein syn-thesis was optimum at the initial-and mid-logarithmic growth phases for both strains. Oxygen demand was observed to be very high during the cloned gene expression, and could be alleviated to some extent through pH control. The ratio of specific growth rates of plasmid-harboring to plasmidfree cell, $\mu$+ /$\mu$-, of the high productivity strain was observed to be lower than that of the low productivity one. Plasmid stability was analyzed for 20-30 generations, and it was found that the traction of plasmid-harboring cells dropped to l0% level in about 25 generations for both strains when the cloned gene expression was induced.

• Applied Biological Chemistry
• /
• v.32 no.4
• /
• pp.424-434
• /
• 1989

The rationale for the use of fungi in treating waste streams from food processing plants I~as been that of incorporating the dissolved and suspending nutrients into a macroscopic organism which can be filtered out readily. In order for a process using fungi to meet these objectives we examined a strain of fungi, Aspergillus fumigatus, which grew well on a variety of polysaccharide-containing materials and showed both efficient BOD removal and high quality protein recovery. In this experiment the fungal choice was based on the laboratory screening studies where the criteria used was BOD and COD reduction, growth response, mycelial yield, and the ability to compete with the natural flora. In the fermentation system used far the continuous culture of Aspergillus fumigatus the best combination of operating variables, inoculum ratio, temperature, initial pH, fermentation time and agitation rate was 5%(v/v), $35{\sim}40^{circ}C,\;pH\;4.5{\sim}5.0$, 2days and 150rpm, respectively. The fungus reduced BOD and COD to 94.0 and 90.4%, respectively and 3.15g of dry mycelium per liter of alcohol waste was harvested during 48hr of incubation time. The protein efficiency ratios for the control diet and the experimental diet containing the fungal protein were $3.42{\pm}0.15$ and $3.40{\pm}0.43$, respectively.

• KSBB Journal
• /
• v.13 no.6
• /
• pp.681-686
• /
• 1998

Effect of glucose feeding strategy and initial concentration of glucose on Serratia marcescens ATCC 27117 in high cell density fed-batch fermentation was investigated. The final biomasses in batch, constant feeding, constant and exponentially feeding strategy at glucose starvation condition in fed-batch were 1.40, 5,07, 6,93 and 7.60 g/L at 40, 41, 24 and 40 hrs, respectively. Productivities of biomass were 0.035, 0.124, 0.289 and 0.190 g/L$.$h, respectively. As a result, constant feeding strategy at starvation condition was 1.5∼8.6 times higher than other strategies. The relationship between dissolved oxygen and glucose feeding times was good identified in exponential feeding strategy and constant feeding strategy at starvation condition. And high cell density cultivation was obtained when minimal media was used.