• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.383-385
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• 1999

Effects of temperature and initial pH of the medium on production of citric acid from cheese whey permeate by Aspergillus niger were investigated. A. niger was cultivated at four different temperatures (27, 30, 33, $36^{\circ}C$) and four different pHs (2, 3, 4, 5) for 15 days. During the fermentation the concentrations of lactose and citric acid in the culture broth were measured. The maximum production of citric acid which was 33.9 g/l (68.26% yield based on lactose utilized) was obtained at $33^{\circ}C$ and pH 3. The production of citric acid was not much affected by shaking speed. However, the shaking speed was found to influence the form of pellets during cell growth.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.934-939
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• 2001

The growth inhibition of Campylobacter jejuni ATCC 33291 in the presence of $1\%$ acetic acid at 4, 25, and $42^{\circ}C$, followed by $25^{\circ}C$ and $4^{\circ}C$, at pH 5.5 and pH 6.5, and by the addition of $1\%$ acetic acid aat 4, 25, and $42^{\circ}C$ were determined to be 22, 8.5, and 1.4 min, respectively, in an FBP-SBB medium. The D values of C. jejuni were increased by the addition of chicken and did not follow the linear relationship observed in the FBP-SBB media without chicken. When using distilled water instead of FBP-SBB in the model system, the death rate of C. jejuni was dramatically accelerated. The injured or low cell numbers that were impossible to enumerate using the plate count method, were detected by a polymerase chain reaction and enrichment culture procedure. These results suggested that acetic acid is reliable and effective as a disinfectant, however, it is necessary to take additional care at refrigeration temperatures due to the potential of injred cells during poultry processing.

• Journal of Microbiology and Biotechnology
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• v.9 no.1
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• pp.56-61
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• 1999

Pseudomonas sp. SW1 grew and produced biosurfactants on 3% hexadecane as the energy and carbon source. As a result of biosurfactant synthesis, the surface tension of the medium was reduced from 72 dyne/cm to 30 dyne/cm. The properties of biosurfactants that were purified from Pseudomonas sp. SW1 were investigated. The purification procedure included acid precipitation from culture supernatant, silica gel G60 column chromatography, and Sephadex G-150 gel filtration. The biosurfactants were separated into two different types, viz., types I and II. Biosurfactant type Isignificantly reduced the surface tension of water from 72 to 27 dyne/cm at concentration levels above 30 mg/l. The surface tension of water was reduced to a minimum of approximately 30 dyne/cm by biosurfactant type II at concentration levels over 80 mg/l. The biosurfactants were effective in a wide range of pHs, at NaCl concentrations of up to 4%, at $CaCl_2$ concentration up to 100 mM, and at temperatures up to $200^{\circ}C$ for 8 h.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.813-818
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• 2013

In order to understand the co-culture impact of the sea squirt Halocynthia roretzi on the Pacific oyster Crassostrea gigas, we examined the filtration rate of the sea squirt in relation of water temperature ($5-25^{\circ}C$) and body weight. The filtration rate increased in relation to body weight and water temperature, indicating a clear positive correlation with the two variables. Due to the clear positive correlation between filtration rates at each temperature groups for acceptable collinearity, each constants at regression equation was further analyzed for a unified model of filtration rate. Therefore the filtration rate of H. roretzi was estimated as: Fr (L/h/animal)=$(0.1956+0.0182T){\times}DW^{0.7978EXP(-0.0273T)}$ for water temperature in the range of $5-25^{\circ}C$. The estimated filtration rates of H. roretzi were higher than those of C. gigas in the winter season (water temperatures below $16^{\circ}C$) in condition of equal body weight. Our results indicate that H. roretzi may have an advantage over C. gigas in food competition during the winter season when the two species are co-cultured.

• BMB Reports
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• v.40 no.6
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• pp.1002-1008
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• 2007

PreS domain of Hepatitis B virus (HBV) surface antigen is a good candidate for an effective vaccine as it activates both B and T cells besides binding to hepatocytes. This report deals with overexpression and purification of adr subtype of surface antigen that is more prevalent in Pakistan. PreS region, comprising 119 aa preS1 region plus a 55 aa preS2 region plus 11 aa from the N-terminal S region, was inserted in pET21a+ vector, cloned in E. coli $DH5\alpha$ cells and expressed in E. coli BL21 codon+ cells. The conditions for over expression were optimized using different concentrations of IPTG (0.01-5 mM), and incubating the cells at different temperatures (23-$41^{\circ}C$) for different durations (0-6 h). The cells were grown under the given optimized conditions (0.5 mM IPTG concentration at $37^{\circ}C$ for 4 h), lysed by sonication and the protein was purified by ion exchange chromatography. On the average, 24.5 mg of recombinant protein was purified per liter of culture. The purified protein was later lyophilized and stored at $-80^{\circ}C$.

• Journal of Food Hygiene and Safety
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• v.13 no.1
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• pp.1-5
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• 1998

This study was carried out to measure the antibacterial effect of lactoperoxidase/ thiocyanate/hydrogen peroxide system (LP system) against E. coli 0157:H7. When the initial inoculum levels (($10^{2},\;10^{4},\;10^{7}cfu/ml$), concentration of LP (10 ppm, 20 ppm, 30 ppm), culture media (TSB-YE, UHT milk, raw milk) and storage temperatures ($5^{\circ}C,\;10^{\circ}C,$15$^{\circ}C$) were set up differently for the experiment and the antibacterial effect was compared, the highest antibacterial effect of LP system was shown at $10^{2}cfu/ml$ of initial inoculum level, 10 ppm of LP concentration and $5^{\circ}C$ of incubation temperature.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.820-825
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• 1999

A bacterial strain WN9, which produced a new type of extracellular polysaccharide, was isolated from soil samples. By morphological, physiological, biochemical, and phylogenetic studies, strain WN9 was identified as a Paenibacillus sp. and it was named as Paenibacillus sp. WN9, which produced a high molecular extracellular polysaccharide from glucose. The molecular weight of the exopolysaccharide (EPS-WN9) was estimated to be about 31.5 mega-Da. The FT-IR spectrum of EPS-WN9 revealed typical characteristics of polysaccharides. EPS- WN9 consisted of D-glucose and D-mannose with a molar ratio of 1:1.4 being identified as a neutral sugar component. The acidic component of EPS- WN9 was tyrosine. Rheological analysis of EPS- WN9 revealed that the pseudoplastic property and its apparent viscosity remained stable at various temperatures and pHs.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.515-521
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• 1994

A bacterial strain, which showed the high protease activity at low temperature and the high tolerance for the surfactant, was isolated from soil and identified as Xanthomonas sp. YL-37. The optimal temperature, initial pH, and cultivation time for the production of the alkaline protease by Xanthomonas sp. YL-37 were 20$\circC , 11.0, and 84 hours, respectively. In the jar fermenter culture of Xanthomonas sp. YL-37, the alkaline protease activity was about 15,000 DU/ml/-broth after cultivating for 108 hours. The optimal pH and temperature for the protease activity were 70$\circC and 11.0, respectively. The protease was relatively stable at the pH range of 7.0~12.0 and at the temperatures below 50$\circC . The protease activity at 20$\circC was about the level of 40% of its activity at 70$\circC . The enzyme was suggested as a serine protease because the enzyme activity was inhibited by phenylmethane sulfonyl fluoride, a serine modifier.

• Korean Journal of Microbiology
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• v.14 no.2
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• pp.84-94
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• 1976

Cellulase components, CMCase(Cx) and Avicelase$(C_1)$, were partially prueified, from the culture extract of a strain of Trichoderma koningii by column chromatography on DEAE-Sephadex A-50 and the step of gel filtration through Sphadex G-150, Optimum pH of CMCase was 5.2 and Avicelase showed the highest activity at pH 5.6 in acetate buffer. Optimal temperatures for activities of CMCase and Avicelase were $50^{\circ}C\;and\;60^{\circ}C, $ respectively. More than 70% of the activities of two enzymes were remained after heating at $60^{\circ}C$ for 30 min and Avicelase is more stable than any other fungal enzymes. The Michaelis constants, Km, of CMCase and Avicelase were 0.116% of CMC and 0.281% of avicel. And also the values of maximum velocity, Vmax, of CMCase and Avicelase were $23.20{\mu}g\;and\;2.54{\mu}g$ of reducing sugar per min. Of the metal ions tested against the activites of CMCase and Avicelase, $Cu^{++}, \; Hg^{++}, \;and\;Pb^{{++}$ are remarkably effective inhibitors. The molecular weights of Cx and $C_1$ component were estimated to be about 47, 000 and 61, 000 by gel filtration method.

• Journal of Food Hygiene and Safety
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• v.13 no.2
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• pp.83-86
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• 1998

This study was carried out to measure the antibacterial effect of lactoperoxidase system against L. monocytogenes. When the initial inoculum levels ($10^{2},\;10^{4},\;10^{7}\;CFU/ml$), concentration of LP (10 ppm, 20 ppm, 30 ppm), culture media (TSB-YE, UHT milk) and storage temperatures ($5^{\circ}C,\;10^{\circ}C,\;15^{\circ}C$) were set up differently for the experiment and the antibacterial effect was compared, the highest antibacterial effect of LP system was shown at $10^{2}\;cfu/ml$ of initial inoculum level, 10 ppm of LP concentration and $5^{\circ}C$ of incubaction temperature. The antibacterial effect of LPS in UHT milk was similar to that in Tryptic soy broth.