• Korean Journal of Microbiology
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• v.42 no.3
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• pp.223-229
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• 2006

To develop multifunctional microbial inoculant, an insluble phosphate-solubilizing bacterium with antifungal activity was isolated from plant rhizospheric soil. On the basis of its morphological, cultural and physiological characteristics and Biolog analysis, this bacterium was identified as Pseudomonas fluorescens RAF15. P. fluorescens RAF15 showed antifungal activities against phytopathogenic fungi Botrytis cinerea and Rhizoctonia solani. The optimal medium composition and cultural conditions for the solubilization of insoluble phosphate by P. fluorescens RAF15 were 1.5% of glucose, 0.005% of urea, 0.3% $MgCl_2{\cdot}6H_2\;0.01%\;of\;MgSO_4{\cdot}7H_2O\;0.01%,\;of\;CaCl_2{\cdot}2H_2O$, and 0.05% of NaCl along with initial pH 7.0 at $30^{\circ}C$. The soluble phosphate production under optimum condition was 863 mg/L after 5 days of cultivation. The solubilization of insoluble phosphates was associated with a drop in the pH of the culture medium. P. fluorescens RAF15 showed resistance against different environmental stresses like $10-35^{\circ}C$ temperature, 1-4% salt concentration and pH 2-11 range. The strain produced soluble phosphate to the culture broth with the concentrations of 971-1121 mg/L against $CaHPO_4$, 791-908 mg/L against $Ca_3(PO_4){_2}$, and 844 mg/L against hydroxyapatite, respectively. However, the strain produced soluble phosphate to the culture broth with the concentrations of 15 mg/L against $FePO_4$, and 5 mg/L against $AlPO_4$, respectively.

• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.658-662
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• 2008

Effects of pH shock on the secretion system of S. coelicolor A3(2) have been investigated at a transcriptional level by using DNA microarrays. Actinorhodin secretion was observed to be highly enhanced when an acidic-pH shock was applied to surface grown cultures of S. coelicolor A3(2). In this culture, a gene of actVA-orf1 encoding a putative efflux pump or transporter protein for actinorhodin was strongly upregulated. A major number of efflux pumps for other metabolites and a major number of secretion proteins for protein secretion were also observed to be upregulated with pH shock. The secretion of actinorhodin was observed to be remarkably enhanced in liquid culture as well.

• KSBB Journal
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• v.10 no.3
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• pp.292-297
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• 1995

Studies on the production of Newcastle disease virus(NDV) were carried out to optimize culture conditions such as initial pH, temperature, serum concentration, multiplicity of infection(M.O.I.) as well as the addition of polycation, antioxidant, and DMSO. Initial pH from 7.2 to 8.1 showed little difference on NDV production but the initial pH below 6.8 resulted in the negative effect. The highest NDV titer was obtained at 0.1 M.O.I. In addition, the maximum production of virus was achieved at 2% FBS and optimum temperature was found to be $34^{\circ}C$. Treatment of polycoation increased the virus production. When ascorbic acid was added as an antioxidant, NDV production was also enhanced. Utilization of DMSO, a well-known permeabilizing agent, showed an inhibitory effect on the propagation of NDV.

• KSBB Journal
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• v.10 no.4
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• pp.421-427
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• 1995

A fungal strain, designated Aspevgillus sp. JS-42, was isolated and shown to produce an extracellular polysaccharide used as a bioflocsulant. The optimal medium composition for the production of flocculant with Aspergillus sp. JS-42 was glucose 3.0%, yeast extract 0.2%, $(NH_4)_2S0_4 0.1%, CaCI_2.2H_2 0.05%$ in distilled water. The optimum culture temperature and optimum culture pH for the production of the flocculant were $25^{\circ}C$ and pH 7.0, respectively. The highest production of flocculant was observed after 90 hours of cultivation at the optimal condition. The flocculant could efficiently flocculaled the tested solids suspended in aqueous solution and was stable at high temperature($100^{\circ}C$) and to pH range of from 2 to 10. The flocculant seems to be a kind of high viscous polysaccharide.

• Journal of Embryo Transfer
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• v.31 no.1
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• pp.89-95
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• 2016

The present study was conduct to examine the $H_2O_2$ expression level and apoptosis-related gene expression levels inporcineskin-derived stem cell-like cells (pSSCs) after adipogenic, chondrogenic, and osteogenic differentiation induction. The pSSCs were obtained by digestion of porcine ear skin biopsy and cultured in each induction medium for 21 to 26 days to induce adipogenic, chondrogenic, and osteogenic differentiation, respectively. The $H_2O_2$ levels of pSSCs after induction culture were evaluated by staining with 2'7'-dichlorodihydrofluorescein diacetate ($H_2DCFDA$). The apoptotic gene expression of pSSCs after induction culture was also estimated by RT-PCR. The pSSCs have a potential to differentiate into three mesodermal cell types (adipocytes, chondrocytes, and osteoblasts). Non-induced control and chondrogenic-induced cells were showed higher $H_2DCFDA$ intensity (P<0.05) than adipogenic- and osteogenic-induced cells. The relative expression of Bax/Bcl-2 level was significantly low (P<0.05) in adipogenic- and osteogenic-induced cells compared to non-induced control. However, there was no difference in the relative expression of Bax/Bcl-2 level among differentiation induction groups. The result of the present study shows that the apoptosis of pSSCs is not detrimentally increased by differentiation induction culture, although chondrogenic-induced pSSCs showed high ROS generation level and apoptotic index similarly to those of non-induced cells.

• Korean Journal of Medicinal Crop Science
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• v.8 no.2
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• pp.123-128
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• 2000

This study was carried out to determine factors affecting on the mass propagation of Rehmannia glutinosa seedlings in bioreactor culture. Air-lift type bioreactor was more compatible to shoot formation than stirrer type. Fifty grams(90 stem explants) of inoculum in 1.5L medium was placed into 2.5L bioreactor with aeration rate of 0.5 v.v.m., which was proper for effective shoot formation. Adding MES as pH buffer to culture medium increased the numbers of shoot formation. Adding 5g/l of anti-vitrifying agent into culture medium was highly effective for diminishing the rate of vitrification in shoots formed.

• Journal of Plant Biology
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• v.20 no.2
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• pp.63-69
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• 1977

Experiments were conducted to investigate the effects of several hormones on the growth of suspension culture of carrot (Daucus carota L.) cells, where changes in pH and the amount of $NH_4-Nin$ the medium were observed with regard to growth. A treatment with 2,4-D at $10^{-5}M$ resulted in a highest rate of growth; the hormone at this concentration caused an increase in dry weight by about 40 to 50% over the control, measured at a stationary phase. It was thus indicated that 2,4-D at $10^{-5}M$ provided the optimal condition for the suspension culture. Changes in pH of the medium were found to be affected by hormonal treatments during the first 2-3 days following the inoculation, after which the pattern of pH changes in hormone enriched media paralleled that of the control. Subsequent changes of $NH_4-N and NO_3-N$ from the medium by the cells, and also by growth of the cells. The uptake of $NH_4-N$ by the cells did not appear to be influenced by hormonal treatments. At a stationary phase, a considerable amout of $NO_3-N$ played a more important role than $NH_4-N$ in the growth of the carrot cell suspension culture.

• Preventive Nutrition and Food Science
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• v.6 no.4
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• pp.206-210
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• 2001

Starch is an abundant resource in plant biomass, and it should be hydrolyzed enzymatically into fermentable sugars for ethanol fermentation. A genetic recombinant yeast, Saccharomyces cerevisiae GA-7458, was constructed by integrating the structural gene of both $\alpha$-amylase from Bacillus stearothermophilus and the gene (STA1) encoding glucoamylase from S. diastaticus into the chromosome of S. cerevisiae SH7458. The recombinant yeast showed active enzymatic activities of $\alpha$-amylase and glucoamylase. The productivity of ethanol fermentation from the pH-controlled batch culture (pH 5.5) was 2.6 times greater than that of the pH-uncontrolled batch culture. Moreover, in a fed-batch culture, more ethanol was produced (13.2 g/L), and the production yield was 0.38 with 2% of corn starch. Importantly, the integrated plasmids were fully maintained during ethanol fermentation.

• Journal of Environmental Health Sciences
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• v.31 no.2 s.83
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• pp.127-133
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• 2005

This study was performed to investigate the competitive effect of Leuconostoc mesenteroides and Lactobacillus plantarum on the growth and aflatoxin $B_1$ production of Aspergillus parasiticus. Leu. mesenteroides and Lac. plantarum were grown with A. parasiticus in a modified APT broth at $28^{\circ}C$ for 9 days. It was observed that the growth of A. parasiticus got lower when the two bacteria were inoculated simultaneously than when the mold grew alone. The pH of mixed culture of Leu. mesenteroides and Lac. plantarum showed significantly lower value than the pH of the pure culture of A. parasiticus (p<0.05). The acidity of the mixed culture group significantly increased compared with the control group (A. parasiticus alone group) (p<0.05). The aflatoxin $B_1$ production was significantly decreased in the mixed culture group than in the A. parasiticus alone group (p<0.05). Leu. mesenteroides showed the more efficient effect than Lac. plantarum. These results indicate that the two lactic acid bacteria have inhibitory effect on the growth and aflatoxin $B_1$ production of Aspergillus parasiticus.

• The Korean Journal of Mycology
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• v.48 no.2
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• pp.75-85
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• 2020

The collection of biological data of indigenous species must comply with the Nagoya Protocol. Fungi contain various bioactive substances making them an attractive source of several products, including food and medicines. In this study, we investigated the growth characteristics of five indigenous fungal strains, Fomitiporia punctata, Polyporus ulleungus, P. brumalis, Gymnopus subnudus, and Tyromyces kmetii, isolated from samples collected in the Ulleungdo Island. The growth rates for each strain were assessed across various temperatures (20 ℃ to 35 ℃), culture media (Potato dextrose agar, Malt extract & Yeast extract agar, Malt extract agar, Malt extract & peptone agar, Sabouraud dextrose agar, and Modified Melin-Norkrans agar), and pH conditions (4.0 to 8.0). Additionally, we assessed the mycelial growth characteristics in liquid culture. The mycelial growth in different media varied across species; specifically, F. punctata (in MMNA), G subnudus (in MMNA), and P. brumalis (in MEPA) showed rapid growth. Optimal growth temperatures ranged between 25 ℃ and 30 ℃ for most species, with the exception of T. kmetii and P. brumalis, which were able to grow across all the temperatures tested. P. brumalis showed the best growth rate, whereas P. ulleungus showed the lowest growth potential. The optimal pH conditions for mycelial growth ranged between 4.0 and 5.0. In experiments using culture flasks, the dry weight of the culture filtrates decreased with the increasing incubation time and showed a significant decrease between 1 and 6 months of incubation, indicating that the five strains take longer than a month to fully use the culture media. Our findings highlight and establish the optimal growth conditions for five different fungal species that can be used in future application studies.