• Korean Journal of Microbiology
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• v.29 no.6
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• pp.387-391
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• 1991

Methylobacterium extorquens AM1 growing on methanol as a sole source of carbon and energy was found to grow most rapidly (t$t_{d}$ =6h) at 30.deg.C in a mineral medium (pH 7.0) containing 0.5% (v/v) methanol which was agitated at 200 rpm (optimal cultivation condition). Cells grown under the optimal cultivation condition contained more spermidine, but less putrescine, than the cells grown on 2.5%(v/v) ( $t_{d}$ =8h ) or at 20.deg.C ( $t_{d}$ =8h ). Cells cultivated under the optimal condition was found to contain more spermidine than the cells grown at pH 6.0 (( $t_{d}$ =7h ) and pH 8.0 ($t_{d}$ =7.3h). the cells growing at the stationary phase under the optimal condition accumulated more spermine or putrescine than the cells growing at the same phase on 2.5%(v/v) methanol or at pH 6.0 and pH 8.0, respectively. M. extorquens AM1 grown in a medium agitated at 100 rpm ( $t_{d}$ =8.8h ) contained less spermidine and spermine than the cells grown under the optimal cultivation condition.

• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.112-115
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• 1987

Optimal pH temperature and sucrose content for the production of vitamin B$_{12}$ and riboflavin by Bacillus megaterium and Enterobacter aerogenes was studied by microbiological analysis. Optimal pH for the production of B$_{12}$ was 6.0 by B. megaterium while the pH for E. aerogenes was 5.0. However, upon the addition of sucrose the optimal pH for B. megaterium shifted to 7.5 but E. aerogenes remained at pH 5.0. In the absence of sucrose, pH did not influence the yields of riboflavin produced by either bacterium. Addition of sucrose stimulated synthesis of riboflavin by both bacteria. Temperature had little effect on the production of vitamins by either bacterium.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.525-528
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• 2001

The purpose of this study is to looking for the optimal condition of methane production enhancement. The conditions tested for increasing methane production were temperature. pH. and various carbon sources including methanol. formic acid. sodium acetate. succinic acid. and glucose. As a result, optimal temperature was 55 .C and optimal pH was around neutral condition. And methanol seemed to be best carbon source which can drastically increase methane production.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1856-1861
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• 2006

A Bacillus sp. A-6 strain that produced xylanase was isolated from rice bran. The optimal temperature and pH for xylanase activity of the culture supernatant of Bacillus sp. A-6 were 40$^{\circ}C$ and pH 7, respectively. The optimal temperature and pH for xylanase production in the xylan medium were 30$^{\circ}C$ and pH 9, respectively. The optimal concentrations of oat spelt xylan and peptone for xylanase production were 0.5% and 1.5%, respectively. The best nitrogen sources for xylanase production was beef extract, but xylanase production was also supported comparably by tryptone and peptone. The bacterial growth in the optimal xylan medium reached stationary growth phase after 12 h of incubation. The xylanase production in the culture supernatant increased dramatically during the initial 12 h exponential growth phase and then remained constant at 23.8-24.5 unit/ml during the stationary growth phase. The pH of the culture medium decreased from 8.8 to 6.7 during the exponential growth phase and subsequently increased to 8.1 during the stationary growth phase. Rice bran, sorghum bran, and wheat bran as well as oat spelt xylan induced xylanase production. The xylanase production was repressed when glucose was added to the xylan-containing medium.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.267.2-267.2
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• 2013

In the citrate reduction method of gold nanoparticle (AuNP) synthesis, pH of the reaction mixture can have a considerable impact on the size and size distribution of AuNPs. In this work, effects of pH variation upon the size and its distribution were examined systematically. As the initial pH was change from 5.5 to 10.5, it showed an optimal pH around 7.5. At this pH, both of the size and the size distribution showed their minimum values, which was verified by transmission electron microscopy and UV-vis spectroscopy. This occurrence of optimal pH was discussed with the results of in situ monitoring pH during the reaction of AuNP synthesis.

• Korean Journal of Veterinary Research
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• v.55 no.3
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• pp.175-179
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• 2015

Proteases play important roles in parasite development and host parasite interactions. The protease of Kudoa spp. has been recognized as a key factor of severe proteolysis of fish muscle post-mortem; however, there is little information available regarding the protease of Kudoa (K.) septempunctata, which was recently identified as a cause of food poisoning in humans. The present study was conducted to isolate and characterize proteases to elucidate the type of protease contained in the parasite and determine the optimal pH for protease activity. We confirmed the cysteine protease and metalloprotease produced by K. septempunctata. While the cysteine protease showed optimal activity at pH 5 that decreased rapidly with increasing pH, the optimal activity of metalloprotease was pH 7, and it remained stable from pH 6 to pH 8. These results indicate that the pH of cysteine protease is not proper for fish muscle postmortem, and that metalloprotease can act in human intestines. Overall, the present study provides important information that improves our understanding of the role of protease physiology and the subsequent food poisoning caused by K. septempunctata.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.742-747
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• 2004

Solid-liquid separation of swine wastewater was conducted using bentonite as coagulant. During the separation experiment, coagulation efficiency was also investigated. To determine optimal bentonite dose, 0.1, 0.2, 0.4, 0.8, and 1.6% (w/v basis) of bentonite was dosed. Suspended solid removal efficiency was 87-98% at whole bentonite dosage. But sediment volume was increased, and settling velocity was decreased at excessive bentonite dosage. Therefore optimal bentonite dosage was evaluated around 0.2-0.4%. In the test to determine optimal pH, coagulation using bentonite was performed at pH 3, 4, 5, 6, and 7. At lower pH suspended solid removal efficiency was increased. However, sediment volume was also increased and phosphorus release was observed. Thereby optimal pH for bentonite coagulation might be appeared in the range of 6-7.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.304-310
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• 1995

A thermophilic bacterium producing the extracellular cellulase-free xylanase was isolated from soil and has been identified as Bacillus sp. The optimal growth temperature was 50$\circ$C and the optimal pH, 7.0. Under the optimal growth condition, maximal xylanase production was 2.2 units/ml in the flask culture. The enzyme production was induced by xylan and xylose, but was repressed by sucrose or trehalose. The partially purified xylanase was most active at 70$\circ$C. It was found that the enzyme was stable at 65$\circ$C for 10 hours with over 75% of the activity. The enzyme was most active at pH 7.0 and retained 90% of its maximum activity between pH 5.0 and pH 9.0 though Bacillus sp. was not grown on alkaline conditions (>pH 8.0). In addition, the activity of xylanase was over 60% at pH 10.0. At the ambient temperature, the enzyme was stable over a pH range of 5.0 to 9.0 for 10 h, indicating that the enzyme is thermostable and alkalotolerant. The activity of xylanase was completely inhibited by metal ions including Hg$^{2+}$ and Fe$^{2+}$, while EDTA, phenylmethylsulfonyl fluoride (PMSF), $\beta$-mercaptoethanol and SDS didn't affect its activity. The enzyme was also identified to exert no activity on carboxymethylcellulose, laminarin, galactomannan, and soluble starch.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.75-80
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• 2015

Pseudoalteromonas donghaensis HJ51, isolated from the East Sea, has been reported as a novel strain to produce extracellular protease. Crude supernatant was used to determine optimal activity and optimal production conditions for the enzyme. It was found that the optimal temperature and pH of the protease were $40^{\circ}C$ and pH 7.5-10.5, respectively. The enzyme activity was kept to 88% at the pH 11. In metal requirement analysis, the enzyme exhibited the highest activity when 10 mM $Fe^{3+}$ was supplied. While supplementation of additional carbon sources used in study showed no positive effect on cell growth and enzyme activity, the addition of beef extract, tryptone, or casamino acids instead of peptone of PY-ASW containing 1% glucose increased enzyme production to 21, 7, 4%, respectively. Taken together these properties, the enzyme produced from P. donghaensis HJ51 can be applied to the industries that require protease activity under alkaline pH and low temperature.

• The Korean Journal of Mycology
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• v.20 no.1
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• pp.58-64
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• 1992

This research was focused on investigation of the general condition for protoplast formation of Trichoderma speues. for protoplast formation, the mycelia cultured in YM medium were collected from each growth phase and were treated with the Iytic enzymes. This procedure was carried out by all strains. The most optimal conditions of NOVOZYM 234 and DRISELASE were determined by T. saturnisporum IAM 12535 and T. longibruchiatum IBM 13107, respectively. The effect of osmotic stabilizers appeared ${KCI}>(NH_4)_2{SO_4}>NaCl>mannitol>{MgSO}_4$ and the optimal concentration of each osmotic stabilizer wns determined by 0.6-0.9 M. The optimal condition of DRISELASE for protoplast formation ; optimal pH 5.0, optimal concentration, 2%, optimal reaction time, 4 hours, and optimal temperature, $30^{\circ}C$. The optimal condition of NOVOZYM 234 for protoplast formation ; optimal pH 5.5, optimal concentration 1%, optimal reaction time 3 hours, and optimal temperature $30^{\circ}C$. The optimal culture period of mycelia for protoplast formation was between the initial and the middle exponential phase. Generally, DUSELASE was more effective than NOVOZYM 234 on protoplast formation except for T. longibruchiatum IAM 13107 and T. viride IAM 5141.