• KSBB Journal
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• 제6권3호
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• pp.299-307
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• 1991

In this paper the effect of light on non-aerated Baker's Yeast(Saccharomyces cereuisiae) production and the protein excretion to the extracellular fluid is studied. Previous results in our laboratory indicate that at pH=5 and T-32$^{\circ}C$ yeast may be affected by light, but those differences seem to be within statistical variation of the data. In this paper, cell and extracellular protein concentrations along with redox potential are monitored for batch fermentations in the presence and absence of light at pH levels of 3 and 5 and at 31$^{\circ}C$, in order to explore whether possible light effects can be more readily discerned at lower pH values. Yeast particle size distributions are also determined over the course of fermentation using a particle counter in order to add one more measuring tool to our usual cell and total protein measurements. An apparently noticeable difference in the redox potential is observed between the light and the dark runs for early times for the pH=3 runs. The particle size distributions show differences in the particle diameters between light and dark runs at pH=3, but those differences fall within one standard deviation of the mean particle diameters.

• KSBB Journal
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• 제18권4호
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• pp.312-317
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• 2003

Glycine의 배양액 첨가에 의해 Pseudomonas aurantiaca S-4380 유래 재조합 levansucrase의 세포 외 분비가 촉진된다는 것을 알 수 있었다. 배지액에 존재하는 glycine 농도에 비례 의존적으로 균체 내에서 발현된 효소의 분비량이 증가되었고, 세포의 성장은 억제됨을 알 수 있었다. SDS-PAGE 분석결과 0.5％, 1.0％ glycine 첨가로 배양시간이 증가하면서 세포내의 단백질 배양액으로 분비됨을 알 수 있었다. Levansucrase를 분비시키기 위한 최적화된 조건은 pH을 6.9-7.0으로 조절하면서 1.0％ glycine을 배양초기 첨가하였을 때 배양말기에 단백질의 급격한 분해 없이 145 U/mL의 효소 활성도를 나타내었다.

• KSBB Journal
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• 제16권2호
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• pp.158-162
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• 2001

A halotolerant and extracellular protease-producing yeast was isolated from traditional Meju and identified as a strain of Hansenular polymorpha by investigating its microbiological characteristics. The optimum pH, temperature and NaCl concentration reauired for the growth of Hansenular polymorpha S-9 were found to be pH 6.0, 30$^{\circ}C$ and 0.5 M, respectively. Extracellular protease was produced maximally at 10 U ml(sup)-1 when Hansenular polymorpha S-9 was grown on the medium containing 1.0% beef extract and 0.1 M NaCl for 12 hr at 30$^{\circ}C$. About 13% of the angiotensin-converting enzyme (ACE) inhibitory activity was shown in the hydrolysates which were obtained from the digestion of soybean protein (6 mg) for 6 hr at 30$^{\circ}C$ by the crude enzyme (1 U).

• 생명과학회지
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• 제23권1호
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• pp.110-115
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• 2013

Extracellular 지질분해효소를 생산하는 균주 AR1은 일본 벳부 온천수에서 분리하였다. 분리된 균주의 16s rRNA 염기서열을 분석하고 계통학적으로 분류한 결과, AR1 균주는 신규 Geobacillus sp.에 속하는 것으로 동정되었다. 본 연구는 Geobacillus sp. AR1 균주의 extracellular 지질분해효소 생산을 향상시키기 위한 새로운 방법에 초점을 맞추었다. AR1 균주는 $35{\sim}75^{\circ}C$의 넓은 온도 범위에서 생육하였고 최적온도는 $65^{\circ}C$이었다. 생육을 위한 최적 pH는 6.5인 반면, 효소 생산을 위한 pH는 8.5로 차이점을 보였다. 배양 중에 지질 화합물의 첨가는 지질분해효소 생산을 유도하였고, soybean oil을 대수증식기에 첨가 했을 때 가장 효율적인 유도 효과를 나타내었다. 한편, 계면활성제는 지질분해효소의 생산을 유도하고 세포 내외의 위치에 영향을 줄 수 있다. AR1 균주는 정지기에 Tween 20을 첨가할 경우, 효소의 세포 외 분비 효율이 크게 증가하였다. 이들 결과를 바탕으로 soybean oil과 Tween 20을 각각 대수증식기와 정지기에 첨가함에 따라 extracellular 효소 생산이 대조구에 비해 2.4배 증가하는 것으로 확인 되었다.

• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.1004-1008
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• 2004

An extracellular acid phytase from Pseudomonas fragi Y9451 was purified to homogeneity from the culture supernatant by salting-out, DEAE-Sepharose column chromatography, CM-Sepharose column chromatography, and Sephacryl S-300 gel filtration. The molecular weight of the purified enzyme was estimated to be 74 kDa on gel filtration and 54 kDa and 25 kDa on SDS-PAGE, suggesting that the native enzyme was a heterodimeric protein. The purified enzyme was most active at pH 4.5 and $70^{\circ}C$ and fairly stable from pH 4.0- 6.0. It was specific for phytate and exhibited a $K_{m}$ value of 27 mM (sodium phytate, pH 4.5, $50^{\circ}C$). The phytase activity was strongly inhibited (at maximum by 87%) by $Fe^{3+},\;Cu^{2+},\;Fe^{2+}$, and $Zn^{2+}$ at 5 mM concentration, and greatly inhibited by $Ca^{2+}$ at 10 mM concentration. However, EDTA notably stimulated the phytase activity at 10 mM concentration. With optimum pH and stability, Pseudomonas fragi phytase could be a potential candidate for animal feed applications.

• Journal of Microbiology and Biotechnology
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• 제6권6호
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• pp.407-413
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• 1996

A novel type of extracellular phospholipase $A_1$ was isolated from Serratia sp. MK1 and purified to homogeneity by ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The purified enzyme was a monomer with a molecular mass of about 43, 000 Da. This enzyme showed the highest lipolytic activity toward phosphatidylserine among the phosphoglycerides tested, and preferentially catalyzed the hydrolysis of the ester bond in phosphatidic acid to lyso-phosphatidic acid. Enzyme activity was completely inhibited by the addition of a chelating agent such as EDTA, and inhibited enzyme activity was fully recovered by the presence of $Ca^{2+}$. This implies that the enzyme requires $Ca^{2+}$ for activity. The enzyme was stable up to $70^{\circ}C$ when incubated for 1 h at pH 8.5, and the optimal pH and temperature were 8.5 and $50^{\circ}C$, respectively.

• 미생물학회지
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• 제26권4호
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• pp.368-374
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• 1988

Bacillus polymyxa YL38-3이 생성하는 세포의 cytosine deaminase의 효소학적 ,성질을 검토하였다. 본 세포외 효소는 열 안정성이 높으며, 인산완충액(pH6.0)과 $30^{\circ}C$에서 효소활성이 최대를 나타냈다. 본 효소는 cytosine 뿐 아니라 5- fluorocytosine-을 기질로 하나, 5-methylcytosine은 촉매하지 않았다. 더우기 본 효소는 $Cd^{2-}$, $Hg^{2+}$의 중금속이온과 ImM p-chloromercuribenzoate에 의하여 완전히 실활되며, o-phenanthroline과 monoiodoacetate에 의하여 75% 저해되었다. 그러나 1mM 2-mercaptoethanol에 의하여 본 효소의 활성을 약 200% 이상 활성화시켰다.

• 미생물학회지
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• 제42권4호
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• pp.326-331
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• 2006

본 연구에서는 경기도 안양에 있는 하천에서 분리한 홍색 비황 광합성 세균Rhodopseudomonas sp. KH4에서 생성된 extracellular polysaccharide (EPS)의 중금속 흡착특성에 대해 연구하였다. 100 mg/L의 Cd과 Cu의 최적 흡착조건(온도$40^{\circ}C$ Cd; pH 8, Cu; pH 5)에서 1.0 g/L의 EPS를 첨가하였을 때, Cd의 경우 30분 동안 842 mg/L, Cu의 경우 10분 동안 70.0 mg/L가 흡착되었다. 또한 Cd과 Cu가 각각 100 mg/L씩 공존되어 있는 경우, pH 5, $25^{\circ}C$에서 EPS 1.0 g/L 첨가하였을 때 Cd과 Cu가 각각 16.8 mg/L, 48.7 mg/L가 흡착되었다. 또한 Langmuir 등은 흡착식으로 부터 EPS 1.0 g/L, pH 5, $25^{\circ}C$에서 Cd과 Cu의 흡착량은 각각 76.9 mg/L, 67.1 mg/L로 실제 경험치와 큰 차이를 보이지 않았다. 에탄올 침전법으로 정제된 KH4 strain으로부터 생성된 EPS는 gas-liquid chromatography (GLC) 분석에 의한 중성당 분석 결과, arabinose, glucose, mannose가 각각 2.4%, 7.1%, 90.5%로 mannose가 대부분을 구성하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제3권2호
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• pp.115-120
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• 1990

Extracellular nuclease(s) in buffalo rumen fluid were purified from strained rumen fluid by a procedure involving Seitz filtration, acetone fractionation and gel filtration on Sephadex G-100. The enzyme resolved into two peaks exhibiting both DNase and RNase activities. The molecular weight of enzyme corresponding to peaks I and II were approximately 30,000 and 12,000 respectively. The properties of enzymes from the two peaks, however, were same. Optimum temperature for both DNase and RNase activities was at $50^{\circ}C$. Whereas DNase activity was stable upto $60^{\circ}C$, RNase activity was stable only up to $50^{\circ}C$. DNase activity recorded two pH optima, one at pH 5.5 and the other at pH 7.0. RNase activity recorded a broad pH optimum between pH 6.0-8.0. pH stability of the enzyme coincided with pH optima for both the activities. DNase activity was stimulated by $Mg^{2+}$ and $Mn^{2+}$ and inhibited by $Fe^{2+}$, $Zn^{2+}$, $Hg^{2+}$ and $Ag^+$. RNase activity was also stimulated by $Mg^{2+}$ and $Mn^{2+}$ and inhibited by $Cu^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Hg^{2+}$ and $Ag^+$. Reducing agents stimulated both the activities.

• The Plant Pathology Journal
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• 제33권3호
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• pp.318-328
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• 2017

Chitinase-producing Paenibacillus elgii strain HOA73 has been used to control plant diseases. However, the antimicrobial activity of its extracellular chitinase has not been fully elucidated. The major extracellular chitinase gene (PeChi68) from strain HOA73 was cloned and expressed in Escherichia coli in this study. This gene had an open reading frame of 2,028 bp, encoding a protein of 675 amino acid residues containing a secretion signal peptide, a chitin-binding domain, two fibronectin type III domains, and a catalytic hydrolase domain. The chitinase (PeChi68) purified from recombinant E. coli exhibited a molecular mass of approximately 68 kDa on SDS-PAGE. Biochemical analysis indicated that optimum temperature for the actitvity of purified chitinase was $50^{\circ}C$. However, it was inactivated with time when it was incubated at $40^{\circ}C$ and $50^{\circ}C$. Its optimum activity was found at pH 7, although its activity was stable when incubated between pH 3 and pH 11. Heavy metals inhibited this chitinase. This purified chitinase completely inhibited spore germination of two Cladosporium isolates and partially inhibited germination of Botrytis cinerea spores. However, it had no effect on the spores of a Colletotricum isolate. These results indicate that the extracellular chitinase produced by P. elgii HOA73 might have function in limiting spore germination of certain fungal pathogens.