• 한국식품과학회지
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• 제46권4호
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• pp.418-424
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• 2014

배 농축액의 유가식 배양을 통해 영양원 없이 산도 12% 이상의 고산도 식초를 제조하면서 발효단계(Stage 1-4) 및 초기 알코올농도(6-9%)에 따른 품질특성 변화를 확인하였다. 환원당, 유리아미노산, 총 페놀 함량, 총 플라보노이드 함량 및 라디칼 소거능은 1차 초산발효한 일반산도 식초에 비해 2차 초산발효한 고산도 식초에서 증가하였고, 이는 유가식으로 첨가된 feeding 알코올의 영향으로 사료되었다. SPME/GC-MS 분석을 통한 20여종의 휘발성분은 식초의 산도에 따라 함량의 차이를 나타내었고, 초기 알코올농도의 증가에 따라 자극적인 향의 acid류 함량이 다소 증가하였다. 이상의 결과, 초기알코올 농도 6-7% 조건에서 유가식 배양으로 제조된 고산도 배식초는 일반산도 식초에 비해 우수한 품질을 나타내었고, 이에 관능특성 및 대규모 생산에 대한 연구가 필요한 것으로 사료되었다.

• 멤브레인
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• 제12권1호
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• pp.21-27
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• 2002

본 연구에서는 회분여과방식을 이용하여 부하율에 따라 생성되는 생물대사성분의 특성 및 분포를 관찰하였다. 실험에 사용된 기질은 단일 탄소인 phenol을 사용하였으며, 분자량 분포실험을 위하여 분자량이 각각 30K, 100K Dalton 및 $0.45{\mu}$ membrane filter를 이용하여 구하였다. 페놀농도가 120, 230 및 440 mg/L 일 때 비기질이용율(q)은 각각 0.639, 1.281, 1.744 (mgTOC/mg MLSS/day)로 나타났으며 Run C일 때 가장 높은 이용율을 나타냈다 . 내생단계에서 미생물의 사멸율($K_d$)는 각각 0.0536, 0.0661, 0.0749($day^1$)이며 생성계수 ($SMP_e$) 는 각각 0.006, 0.0058, 0.0057($day^1$)로 나타났다. 초기 유입된 기질이 기질분해에 의해 생성된 $SMP_s$로 분해되어지며, 시간경과에 따라 $SMP_{nd}$ 로 진행됨을 알수 있었다. 기질분해 완료 후 미생물의 내생단계에 접어들면서 $SMP_e$성분으로 전환되었다. 유입부하율에 따른 분자량 분포 측정결과는 운전시간이 경고함에 따라 점차 저분자 물질이 고분자의 난분해성 물질로 전환되었다.

• 한국간담췌외과학회지
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• 제27권4호
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• pp.342-349
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• 2023

Backgrounds/Aims: Liver organoids have emerged as a powerful tool for studying liver biology and disease and for developing new therapies and regenerative medicine approaches. For organoid culture, Matrigel, a type of extracellular matrix, is the most commonly used material. However, Matrigel cannot be used for clinical applications due to the presence of unknown proteins that can cause immune rejection, batch-to-batch variability, and angiogenesis. Methods: To obtain human primary hepatocytes (hPHs), we performed 2 steps collagenase liver perfusion protocol. We treated three small molecules cocktails (A83-01, CHIR99021, and HGF) for reprogramming the hPHs into human chemically derived hepatic progenitors (hCdHs) and used hCdHs to generate liver organoids. Results: In this study, we report the generation of liver organoids in a collagen scaffold using hCdHs. In comparison with adult liver (or primary hepatocyte)-derived organoids with collagen scaffold (hALO_C), hCdH-derived organoids in a collagen scaffold (hCdHO_C) showed a 10-fold increase in organoid generation efficiency with higher expression of liver- or liver progenitor-specific markers. Moreover, we demonstrated that hCdHO_C could differentiate into hepatic organoids (hCdHO_C_DM), indicating the potential of these organoids as a platform for drug screening. Conclusions: Overall, our study highlights the potential of hCdHO_C as a tool for liver research and presents a new approach for generating liver organoids using hCdHs with a collagen scaffold.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.960-968
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• 2003

A bacterial isolate showing a strong endochitosanase activity was isolated from soil and then characterized. The isolate was identified and designated as Bacillus cereus P16, based on morphological and biochemical properties, assimilation tests, cellular fatty acids pattern, along with 16S rRNA gene sequence. The optimized medium for producing extracellular chitosanase in a batch culture contained 1% tryptone, 0.5% chitosan, and 1% NaCl (pH 7.0). Powder chitosan and tryptone served the best as carbon and nitrogen sources, respectively, for the chitosanase production. Chitosanase activity was the highest when culture was completed at $37^{\circ}C$ among various temperatures ($20-42^{\circ}C$) tested in a shaking incubator (200 rpm). The levels of chitosanase activity in the culture fluid were 2.0 U/ml and 3.8 U/ml, respectively, when incubated in a flask for 60 h and in a jar fermenter for 24 h. The culture supernatant showed a strong liquefying activity on the soluble chitosan. The viscosity of 1% chitosan solution, that was incubated with the culture supernatant, was rapidly decreased, suggesting the secretion of endochitosanolytic enzymes by P16. The culture fluid revealed six endo-type chitosanase isozymes, two major (38 and 45 kD), and four minor (54, 65, 82, and 96 kD) forms by staining profile. The crude enzymes were very stable, and full activity was maintained for 4 weeks at $4^{\circ}C\;or\;-20^{\circ}C$ in the culture supernatant, suggesting a highly desirable stability rate for making an industrial application of the crude enzymes. The supernatant also cleaved the insoluble chitosan powder, but the hydrolysis rate was much lower. The enzymic degradation products of chitosan contained $(GlcN)_n$ (n=2-8). The concentration of chitosan in the reaction mixture of the crude enzyme affected the chitooligosaccharides composition of the hydrolysis products. When the higher concentration of chitosan was used, the higher degree of polymerized chitooligosaccharides were produced. By comparison with other commercial chitosanase preparations, P16 was indeed found to be a valuable enzyme source for industrial production of chitooligosaccharides from chitosan.

• 생명과학회지
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• 제19권4호
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• pp.457-461
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• 2009

본 연구는 Lipomyces starkeyi KCTC 17343에 의한 dextranase 최적 생산 조건을 확립하고 dextran에 대한 효소 분해 특성을 규명하였다. 균주의 성장과 dextranase생산은 발효초기 pH와 온도에 따라 다르며 최적 pH는 4-5, 최적온도는 $25-30^{\circ}C$의 범위에서 결정이 되었다. 최적 발효조건에서의 dextranase 생산은 total enzyme activity가 4.85 IU/ml으로 나타났다. 이때의 발효균주의 specific growth rate는 $0.076h^{-1}$이었다. 발효 중 dextranase의 활성은 발효 정상기에서도 안정성을 유지하였다. Dextranase에 의한 dextran을 가수분해 결과, 가수분해물의 구성은 DP2 to 8에 이르는 올리고 덱스트란으로 이루어졌다.

• KSBB Journal
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• 제13권3호
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• pp.251-258
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• 1998

Scutellaria baicalensis. G. 식물 세포의 현탁 배양에서 세포의 성장과 flavonoid glycosides 생산에 관한 구조적 성장 모텔 을 제안하였다 제안된 모델식은 현탁 배양의 형광을 측정함으 써 결정될 수 있는 세포 생존도와 세포 활동도 등플 세포의 생리학적 변수로서 고려하였다. 제안된 모델식에서는 세포의 상태에 따라 세포블 크게 생존 세포와 비생존 세포로 나누고 생존 세포를 분화 가능한 생존 세포와 비분화 생존 세포로 나누어 각 각의 모델을 구성하였다. 이 중 생존 세포 중량은 광섬유 형광 센서로 측정한 상대 형광 세가로부터 결정될 수 있었다. Flavonoid 배당체의 생산 속도는 분화 가능한 생존 세포와 바 분화 생존 세포에 의해 지배되며, 배양액의 삼투압에 의한 서l포 팽창과 세포내 생성불절의 방출은 비생존 세포에 의해 이루어진다고 가정하였다. 종속변수는 가칠농도(포도당), 세포 중량(건조 세포중량과 생체중량), 대사산물농도(flavone glycosides), 활동도와 생존도플 포함한다 Scutellaria baicalensis. G. 식물 세포 의 푹라스크 배양으로부터 모델과 실험결과가 잘 일치함을 알 수 있었다. 제시된 모델은 세포의 성장, flavone glycosides 및 중간매개체 합성을 예측할 수 있다.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1206-1212
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• 2009

Growth rates, photosystem II photosynthesis, and the levels of chlorophyll $\alpha$ and secondary metabolites of Chlorella ovalis were estimated to determine if they were enhanced by the addition of swine urine (BM) or cow compost water (EP) that had been fermented by soil bacteria to deep seawater (DSW) in an attempt to develop media that enabled batch mass culture at lower costs. Growth of C. ovalis in f/2, f/2-EDTA+BM60%, DSW+BM30%, and DSW+EP60% was enhanced and maintained in the log phase of growth for 16 days. The cell densities of C. ovalis in DSW+EP60% ($4.1{\times}10^6$ Cells/ml) were higher than those of f/2 ($2.9{\times}10^6$ Cells/ml), f/2-E+BM60% ($3.7{\times}10^6$ Cells/ml), and DSW+BM30% ($2.7{\times}10^6$ Cells/ml). The growth rate was also more favorable for C. ovalis cultured in DSW+EP60% ($0.15\;day^{-1}$) than that of C. ovalis cultured in the control medium (f/2) ($0.12\;day^{-1}$). Furthermore, the chlorophyll a concentration of C. ovalis cultured in DSW+EP60% (4.56 mg/l) was more than 2-fold greater than that of C. ovalis cultured in f/2 (2.35 mg/l). Moreover, the maximal quantum yields of photo system II at 470 nm (Fv/Fm) were significantly higher in organisms cultured at f/2-E+BM60% (0.53) and DSW+EP60% (0.52) than in the other treatment groups. Finally, Fourier transformation infrared (FT-IR) spectroscopy revealed that C. ovalis grown in DSW+EP60% had more typical peaks and various biochemical pool shifts than those grown in other types of media. Taken together, the results of this study indicate that the use of DSW+EP60% to culture C. ovalis can reduce maintenance expenses and promote higher yields.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.503-510
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• 2016

The accumulation (internal and superficial distribution) of magnesium ions (Mg²⁺) by the green freshwater microalga Chlorella vulgaris (C. vulgaris) was investigated under autotrophic culture in a stirred photobioreactor. The concentrations of the three forms of Mg²⁺ (dissolved, extracellular, and intracellular) were determined with atomic absorption spectroscopy during the course of C. vulgaris growth. The proportions of adsorbed (extracellular) and absorbed (intracellular) Mg²⁺ were quantified. The concentration of the most important pigment in algal cells, chlorophyll a, increased over time in proportion to the increase in the biomass concentration, indicating a constant chlorophyll/biomass ratio during the linear growth phase. The mean-average rate of Mg²⁺ uptake by C. vulgaris grown in a culture medium starting with 16 mg/l of Mg²⁺ concentration was measured. A clear relationship between the biomass concentration and the proportion of the Mg²⁺ removal from the medium was observed. Of the total Mg²⁺ present in the culture medium, 18% was adsorbed on the cell wall and 51% was absorbed by the biomass by the end of the experiment (765 h). Overall, 69% of the initial Mg²⁺ were found to be removed from the medium. This study supported the kinetic model based on a reversible first-order reaction for Mg²⁺ bioaccumulation in C. vulgaris, which was consistent with the experimental data.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.1-7
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• 2002

The effects of DO and pH on the mass production of pullulan with high molecular weight and the morphology of A. pullulans ATCC 42023 were evaluated. A. pullulans showed a maximum production of pullulan (11.98 g/l) when the initial pH of the culture broth was 6.5 in a shake-flask culture. In a batch culture, the mixture of a yeast-like and mycelial cell forms was found at a pH of 4.5, and the maximum production of pullulan (13.31 g/l) was obtained. However, a high proportion of high molecular weight pullulan (M.W.>2,000,000) was produced at a pH of 6.5, with a yeast-like morphology. The maximum pullulan production yield ($51\%$) was obtained at a pH noncontrol (initial pH 6.5) and DO control (above $50\%$) condition. Pullulan degrading enzyme was activated when the pH of the broth was lower than 5.0 and the portion of low molecular weight pullulan was increased. The formation of a black pigment was observed at an initial stationary phase, at 40 h of fermentation. Therefore, the fermentation should be carried out in a pH noncontrol (initial pH of 6.5) and DO control (above $50\%$) condition, and should be harvested before reaching the stationary phase (around 40 h) for the production of high molecular weight pullulan.

• KSBB Journal
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• 제27권2호
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• pp.97-102
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• 2012

In the present study, the biomass productivity of two green microalgae (Chlorella sp. and Dunaliella salina DCCBC2) were assessed in a 12 L tubular photobioreactor under optimum culture conditions. In the batch culture optimization process, the Chlorella sp. biomass was obtained as 1.2 g/L under atmospheric air as a sole $CO_2$ source and other culture conditions as follows: light intensity, temperature, pH, $NH_4Cl$ and $K_2HPO_4$ were 100 ${\mu}E/m^2/s$, $27^{\circ}C$, 7.0, 20.0 mM and 2.0 mM, respectively. On the other hand, 2.9 g/L of D. salina DCCBC2 biomass production was observed under the following conditions: light intensity, temperature, pH, $KNO_3$ and $K_2HPO_4$were 80 ${\mu}E/m^2/s$, $27^{\circ}C$, 8.0, 3.0 mM and 0.025 mM, respectively. At 1% $CO_2$ supply to the reactor, the Chlorella sp. production was reached 1.53 g/L with 25% increment under the same operating conditions. In addition, the maximum D. salina DCCBC2 biomass was observed as 3.40 g/L at 3% $CO_2$ concentration. Based on the aforementioned optimized conditions, the dilution rate and maximal biomass productivity of Chlorella sp. and D. salina DCCBC2 in the continuous cultivation were 0.4/d and 0.6 g/L/d and 0.6/d and 1.5 g/L/d, respectively.