• Journal of Life Science
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• v.27 no.3
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• pp.339-345
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• 2017

Carotenoids are natural lipid-soluble pigments, which are produced primarily by bacteria, algae, and plants. Many studies have focused on the identification, production, and utilization of natural sources of astaxanthin from algae, yeast, and crustacean byproducts as an alternative to the synthetic pigment, which is mostly used today. The aim of the present study was to identify a mutant of Paracoccus haeundaensis by exposure to UV and ethyl methanesulfonate (EMS). The mutant was then exposed to nutrient stress conditions to isolate an astaxanthin-hyperproducing strain, followed by characterization of the mutant. The survival rate decreased in accordance with an increase in the UV exposure time and an increase in the EMS concentration. A mutant of the original P. haeundaensis strain was identified that showed hyperproduction of astaxanthin following exposure to UV irradiation (20 min) and EMS treatment (0.4 M concentration). The optimal culture conditions for the PUE mutant were $25^{\circ}C$, pH 7-8, and 3% NaCl. The effects of various carbon and nitrogen sources on the growth and astaxanthin production of PUE were examined. The addition of 1% raffinose and 3% potassium nitrate influenced cell growth and astaxanthin production. The selected mutant exhibited an increase of 1.58 folds in astaxanthin content compared to initial wild type strain. A genetically stable mutant strain obtained using mutagen (UV irradiation and EMS treatment) may be a suitable candidate for further industrial scale production of astaxanthin.

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.40-45
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• 2006

The baculovirus-insect Drosophila melanogaster S2 cell system combines advantages of conventional baculovirus system and non-lytic S2 cell system because baculoviruses can infect non-permissive cells such as mammalian and Drosophila S2 cells but cannot replicate themselves inside the cells. In the present work, we investigated effects of infection conditions on production of green fluorescent protein (GFP) as a target protein using this baculovirus-S2 cell system. Even though higher MOI and longer baculovirus contact time showed better GFP expression yield during the shorter period, overall protein yield could be lower during the longer period due to the relatively higher cell detachment and lysis (lower cell viability). In addition, maintaining high MOI will be not practical for large-scale cell culture. Therefore, instead of maintaining high MOI, we found that high initial cell number and concentrated (10X) baculovirus volume can confer comparable protein expression even under the moderate MOI condition. Also, we found that the post-infection time that is connected to state of cells after infection was an important factor for production yield.

• Korean Journal of Microbiology
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• v.36 no.2
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• pp.91-96
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• 2000

The cultural and physiological conditions for the T-2 toxin [4,15-diacetoxy-8-(3-mety1butyloxy)-12,13- epoxy-trichothec-9-en-3-01, $C_{24}H_{30}O_9$] production by Fusarium spp. were studied. Thin layer chromatography (TLC) assay and the microbiological assay uslng Rhodotomla rubra were used to quantitate tbe T- 2 toxin. Among the four strains of Fusarium spp., F tn'cinctum NRRL 3299 was best for T-2 toxin production. In solid culture, white com grit medium was best for T-2 toxm production. Temperature played a critical role in the production of T-2 toxin. T-2 toxin production was favored by long duration of low-temperature incubation. The growth and toxin production were relatively high on galactose, fructose, glucose, and sucrose media, when each was used as a sole carbon source, and relatively low on sorbitol, glycerol, and lactose media. For nitrogen sources, $NH_4^(+) and NO_3^{-}were used well as a sole nitrogen source, but $NO_2^-$ was not used. Initial pH and speed of shaker also affected the production of T-2 toxin. From temperature shifting experiment, it is clear that T-2 toxin metabolic pathway is regulated by temperature-dependent enzyme depression or enzyme induction system.

• Journal of Marine Life Science
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• v.9 no.1
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• pp.9-21
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• 2024

Paralytic shellfish poisoning (PSP) including Saxitoxin (STX) is caused by harmful algae, and poisoning occurs when the contaminated seafood is consumed. The mouse bioassay (MBA), a standard test method for detecting PSP, is being sanctioned in many countries due to its low detection limit and the animal concerns. An alternative to the MBA is the Neuro-2a cell-based assay. This study aimed to establish various test conditions for Neuro-2a assay, including cell density, culture conditions, and STX treatment conditions, to suit the domestic laboratory environment. As a result, the initial cell density was set to 40,000 cells/well and the incubation time to 24 hours. Additionally, the concentration of Ouabain and Veratridine (O/V) was set to 500/50 μM, at which most cells died. In this study, we identified eight concentrations of STX, ranging from 368 to 47,056 fg/μl, which produced an S-shaped dose-response curve when treated with O/V. Through inter-laboratory variability comparison of the Neuro-2a assay, we established five Quality Control Criteria to verify the appropriateness of the experiments and six Data Criteria (Top and Bottom OD, EC₅₀, EC₂₀, Hill slop, and R² of graph) to determine the reliability of the experimental data. The Neuro-2a assay conducted under the established conditions showed an EC₅₀ value of approximately 1,800~3,500 fg/μl. The intra- & inter-lab variability comparison results showed that the coefficients of variation (CVs) for the Quality Control and Data values ranged from 1.98% to 29.15%, confirming the reproducibility of the experiments. This study presented Quality Control Criteria and Data Criteria to assess the appropriateness of the experiments and confirmed the excellent repeatability and reproducibility of the Neuro-2a assay. To apply the Neuro-2a assay as an alternative method for detecting PSP in domestic seafood, it is essential to establish a toxin extraction method from seafood and toxin quantification methods, and perform correlation analysis with MBA and instrumental analysis methods.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.169-175
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• 1980

These studies were conducted to induce the available mutant strains in acetic acid bacteria by the irradiation of UV-light and the treatment of N-methyl-N'-nitro-N'-nitrosoguanidine. 109 strains which were capable of producing acid in the ethanol containing medium were isolated from vinegar and Kimchi collected from the region of Daejeon city. From the collection T-50 strain was identified to have a strong fermentation power and selected as a mother strain for the study. Two mutants were obtained by treating T-50 strain with UV and NTG, and these mutants had a rapid acid production in the initial stage. The study was then made to compare the basic condition for acetic acid production of the mother strain and two mutant strains. The summarized results were as follows; 1. The isolated strain (T-50) was identified as Acetobacter aceti by Bergey's manual and Acetic acid bacteria (Tokyo Univ. press). 2. The selected strain was died completely when the strain was irradiated with 15 W UV-light at a distance of 45 cm for 160 seconds. 3. The mutants such as U-48 and N-67 were rapid in the acetic acid production at the initial stage compare to the mother strain. 4. Acetic acid formation by the shaking culture method was maximized in 2 days culture, and the optimal temperature for acetic acid production was $30^{\circ}C$. 5. Acetic acid was effectively produced by the addition of 0.1% ammonium sulfate as a nitrogen source and was also produced rapidly by the addition of 0.1% glucose.

• The Korean Journal of Mycology
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• v.26 no.2 s.85
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• pp.265-274
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• 1998

This study was carried out to obtain the basic data for an artificial cultivation of Phellinus sp.. The optimum conditions for the mycelial growth on the different sawdusts (Quercus aliena, Morns alba and Alnus japonica) substrate of an isolated Phellinus sp. were optimized by response surface methodology. The ratio of rice bran addition to sawdust and the suitable moisture content for the mycelial growth in the all sawdust media were about 30% (w/w) and $65{\sim}70%$ (w/v), respectively. The initial pHs for the mycelial growth of Quercus aliena and Morns alba were in the range of $pH\;5{\sim}6$, whereas Alnus japonica was obtained at pH 6. The optimum temperature for the mycelial growth was about $25{\sim}30^{\circ}C$, depending on the different kinds of wood substrates. From the response surface analysis, the values of independent variables of Quercus aliena at stationary points were determined to be 31.01 % (w/w) of rice bran, pH of 5.31 and 69.03% (w/v) of moisture content, and the expected value of mycelial growth was about 8.32 cm. Both the ratio of rice bran addition to sawdust $(X_1)$ and moisture content $(X_3)$ were effective to the mycelial growth. In the case of Morns alba, the ratio of rice bran addition to sawdust, initial pH and moisture content at the stationary points were 28.77% (w/w), 5.28 and 69.8 (w/v),respectively, and the expected mycelial growth of 7.60 cm was obtained. Stationary points for the mycelial growth in the sawdust media of Alnus japonica were 28.74% (w/w) of rice bran, pH of 6. 04 and 66.96% (w/v) of moisture content, and the expected values of mycelial growth was about 5.38 cm. Based on the above results, there was correlations between the mycelial growth and independent variables, and the effect of rice bran $(X_1)$ and initial pH $(X_2)$ for the mycelial growth were higher than the moisture content $(X_3)$. The optimum species of sawdust media for the my celial growth of Phellinus sp. was in the order of Quercus aliena > Morns alba > Alnus japonica.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.177-183
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• 2004

The discharge of waste nutrient solution from greenhouse to natural ecosystem leads to the accumulation of excess nutrients that results in contamination or eutrophication. There is a need to recycle the waste nutrient solution in order to prevent the environmental hazards. The amount and kind of nutrients in waste nutrient solution might be enough to grow photosynthetic microorganisms. Hence in the present study, we examined the growth and mass cultivation of cyanobacteria in the waste nutrient solution with an objective of removing N and P and concomitantly, its mass cultivation. Four photosynthetic filamentous cyanobacteria (Anabaena HA101, HA701 and Nostoc HN601, HN701) isolated from composts and soils of the Chungnam province were used as culture strains. Among the isolates, Nostoc HN601 performed faster growth rate and higher N and P uptake in the BG-II ($NO_3{^-}$) medium when compared to those of other cyanobacterial strains. Finally, the selected isolate was tested under optimum conditions (airflow at the rate of $1L\;min^{-1}$. in 15 L reactor, initial pH 8) in waste nutrient solution from tomato hydroponic in green house condition. Results showed to remove 100% phosphate from the waste nutrient solution in the tomato hydroponics recorded over a period of 7 days. The growth rate of Nostoc HN601 was $16mg\;Chl-a\;L^{-1}$ in the waste nutrient solution from tomato hydroponics with optimum condition, whereas growth rate of Nostoc HN601 was only $9.8mg\;Chl-a\;L^{-1}$ in BG-11 media. Nitrogen fixing capacity of Nostoc HN601 was $20.9nmol\;C_2H_4\;mg^{-1}\;Chl-a\;h^{-1}$ in N-free BG-11. The total nitrogen and total phosphate concentration of Nostoc HN601 were 63.3 mg N gram dry weight $(GDW)^{-1}$ and $19.1mg\;P\;GDW^{-1}$ respectively. Collectively, cyanobacterial mass production using waste nutrient solution under green house condition might be suitable for recycling and cleaning of waste nutrient solution from hydroponic culture system. Biomass of cyanobacteria, cultivated in waste nutrient solution, could be used as biofertilizer.

• Applied Biological Chemistry
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• v.48 no.4
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• pp.425-430
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• 2005

[${\beta}-sitosterol$] is a plant sterol that reduces cholesterol levels and inhibits the growth of human prostate and colon cancer cells. Optimal conditions for ${\beta}-sitosterol$ production were examined from cell suspension cultures of Chrysanthemum coronarium L. The callus induction was optimal in MS medium containing 1 mg/l NAA and 1 mg/l BAP. Cell suspension culture was also established from the callus. Optimal ${\beta}-sitosterol$ production was obtained when the cells were cultured at an initial density of 2 mg DCW/l in MS medium containing 1 X sucrose (30 mg/l), 1 X nitrogen (1900 mg/l $KNO_3$, 1650 mg/l $NH_4NO_3$), and 1 X phosphate source (170 mg/l). In cell suspension cultures of C. coronarium L. using shake flasks, the peak content of ${\beta}-sitosterol$ was $150{\mu}g/g$ DCW. In cell suspension cultures of C. coronarium L. using an air-lift bioreactor, the maximum ${\beta}-sitosterol$ content of $143.8{\mu}g/g$ DCW was obtained at an air-flow rate of 100 cc/min.

• The Korean Journal of Malacology
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• v.17 no.1
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• pp.35-44
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• 2001

This research was conducted to develop seedling production techniques in flat oyster, Ostrea dense lamellosa. The cultivation of larvae, artificial spat and spats collection in natural conditions rate were examined. In the mass culture tank (3 tons), average growth rates of the D Shape larvae of initial shell length (153.4 ㎛) and shell height (153.4 ㎛) were 202.6% and 212.9% at 16 days and 227.1%, 241.8% at 20 days, respectively. Instantaneous death and survival rate of the larvae were 0.160 and 54.8% at 16 days and 0.057 and 43.2% at 20 days, respectively. Collection rate of flat oyster from bottom using various collectors with oyster shell, scallop shell, ark shell and PVC plates were 32.9%, 24.1%, 16.8% and 10.0%, respectively. and the greatest collecting rate was 131.9 individuals/shell (32.9%) in laid collectors on the bottom. The collecting rate of the oyster larvae were better in laid collectors on the bottom 83.8 individuals/collection than in the suspended string 54.2 individuals/collection. in all collecting substrates. Early spats settled on collectors were grew to 2.38 $\pm$ 0.97 ㎜ in shell length and 2.16 $\pm$ 0.86 ㎜ In shell height at 26 days. The spats were grew to 28.58 $\pm$ 2.39 ㎜ in shell length and 31.65 $\pm$ 2.03 ㎜ in shell height during the 4 month mid-term cultivation. In the period of cultivation, the mean number of spats attached to collectors were 10.3 individuals at oyster shells, 5.8 scallop shells, 4.0 ark shells and 1.5 PVC plates, respectively.

• KSBB Journal
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• v.14 no.1
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• pp.103-108
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• 1999

A bacterium having strong fibrinolytic activity, S7-16 strain, was isolated from soil. The isolated bacterium was identified and named as Bacillus sp. S7-16. The optimal composition of the medium for the production of fibrinolytic enzyme by Bacillus sp. S7-16 was 0.5%(w/v) polypeptone, 0.5%(w/v) yeast extract, 0.3%(w/v) NaCl, 0.1% (w/v) $KH_2PO_4,\;0.3%(w/v)\;K_2PHO_4,\;and\;0.01%(w/v)\;MgSO_4{\cdot}7H_2O$. The optimal temperature and initial pH of the medium for the production of the enzyme were $35^{\circ}C$ and 7.0, respectively. The maximum production of the fibrinolytic enzyme was obtained after 24 hours of the incubation. Under the above conditions, the culture supernatant had strong fibrinolytic activity. Within pH4~11, the crude fibrinolytic enzyme was stable. The enzyme was stable up to $50^{\circ}C$. The optimum pH and temperature for the enzyme activity were around 7.5 and $40^{\circ}C$, respectively.