• Microbiology and Biotechnology Letters
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• v.25 no.4
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• pp.339-345
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• 1997

Under the light intensity of 25-72$\mu$E/ m$^{2}$/s Botryococcus braunii UTEX 572 grew faster than Botryococcus sp. GE 24 isolated from a freshwater lake. The specific growth rate ($\mu$) of B. braunii UTEX 572 was highest at 0.260 (1/day) on a dry weight basis in Chu 13 medium from 1 to 9 days of incubation and then continuously decreased. Carbohydrate concentration and cellular nitrogen and phosphorus contents of B. braunii UTEX 572 gradually decreased with light intensity over a range of 25-72$\mu$E/m$^{2}$2/s, whereas the concentrations of protein and cellular N:P ratio increased with light intensity. Chlorophyll-a concentration showed a decreasing tendency with light intensity. The dry weight of B. braunii UTEX 572 increased in the highest rate of 83 mg/l/day at pH 8.0. When the N: P ratio of Chu 13 medium was adjusted to 50: 1 by addition of nitrogen source, dry weight increasing rate was 115 mg/l/day between 20 and 28 days of incubation which was the highest value during the cultivation. Cell growth in an open culture of B. braunii UTEX 572 was highest with Chu 13 medium, whereas that with Chu 13 medium adjusted to pH 7.0, containing 250 mg/l penicillin, or containing 1% glucose was reduced on a large scale. However, this result shows the possibility of the mass cultivation of B. braunii UTEX 572 in an open system competing with other microorganisms.

• Journal of Microbiology and Biotechnology
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• v.25 no.3
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• pp.358-365
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• 2015

ε-Poly-L-lysine (ε-PL) is a homopolymer of L-lysine molecules connected between the epsilon amino and alpha carboxyl groups. This polymer is currently used as a natural preservative in food. Insufficient biomass is a major problem in ε-PL fermentation. Here, to improve cell growth and ε-PL productivity, various nitrogen-rich nutrients were supplemented into flask cultures after 16 h cultivation, marking the onset of ε-PL biosynthesis. Yeast extract, soybean powder, corn powder, and beef extract significantly improved cell growth. In terms of ε-PL productivity, yeast extract at 0.5% (w/v) gave the maximum yield (2.24 g/l), 115.4% higher than the control (1.04 g/l), followed by soybean powder (1.86 g/l) at 1% (w/v) and corn powder (1.72 g/l) at 1% (w/v). However, supplementation with beef extract inhibited ε-PL production. The optimal time for supplementation for all nutrients examined was at 16 h cultivation. The kinetics of yeast-extract-supplemented cultures showed enhanced cell growth and production duration. Thus, the most commonly used two-stage pH control fed-batch fermentation method was modified by omitting the pH 5.0-controlled period, and coupling the procedure with nutrient feeding in the pH 3.9-controlled phase. Using this process, by continuously feeding 0.5 g/h of yeast extract, soybean powder, or corn powder into cultures in a 30 L fermenter, the final ε-PL titer reached 28.2 g/l, 23.7 g/l, and 21.4 g/l, respectively, 91.8%, 61.2%, and 45.6% higher than that of the control (14.7 g/l). This describes a promising option for the mass production of ε-PL.

• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.109-118
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• 2015

Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity. Experimental results were then fitted into a model, and cost analysis was performed in comparison with control raceways. Three different microalgal strains, Chlorella vulgaris AG10032, Chlorella sp. JK2, and Scenedesmus sp. JK10, were tested for nutrient removal under different light wavelengths (blue, green, red, and white) using filters in batch cultivation. Blue wavelength showed an average of 27% higher nutrient removal and at least 42% higher chemical oxygen demand removal compared with white light. Naturally, the specific growth rate of microalgae cultivated under blue wavelength was on average 10.8% higher than white wavelength. Similarly, lipid productivity was highest in blue wavelength, at least 46.8% higher than white wavelength, whereas FAME composition revealed a mild increase in oleic and palmitic acid levels. Cost analysis reveals that raceways treating wastewater and using monochromatic wavelength would decrease costs from 2.71 to 0.73 $/kg biomass. We prove that increasing both biomass and lipid productivity is possible through cost-effective approaches, thereby accelerating the commercialization of low-value products from microalgae, like biodiesel.

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1938-1944
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• 2008

The procpb gene encoding human procarboxypeptidase B (proCPB, GeneBank access code AJ224866) was cloned and its Pichia expression plasmid, $pPIC9{\alpha}$/hproCPB (9.2 kb), was constructed, in which procpb was under the control of the AOXl promoter and connected to the downstream of the mating factor ${\alpha}$-1 ($MF{\alpha}1$) signal sequence. The plasmid was linearized by digestion with Sacl, and integrated into the genome of P. pastoris strain GS115. By culturing of Pichia transformant on methanol medium, the human proCPB was successfully expressed and secreted into the culture supernatant. Moreover, Western blot analysis of the extracellular proteins showed proCPB bands clearly at a molecular mass of 45 kDa, confirming the expression of proCPB with its right size. The CPB activity reached about 3.5 U/ml and 12.7 U/ml in the flask and fermentor batch cultures of Pichia transformant, respectively. No CPB enzyme activity was found in the intracellular fraction. When the fed-batch cultivation was performed with methanol and glycerol mixture as a feeding medium, the extracellular CPB activity was increased to 42.0 U/ml, which corresponds to a 3.3-fold higher level of CPB activity than that of batch culture. The $K_m$ and $k_{cat}$ values of recombinant human CPB enzyme for hippuryl-$_L$-Arg as a substrate were estimated to be 0.16 mM and $11.93\;sec^{-1}$, respectively.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.128-134
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• 2008

The kinetics of cell growth and Cyclosporin A (Cyc A) production by Tolypocladium inflatum were studied in shake flasks and bioreactors under controlled and uncontrolled pH conditions. In the case of the shake flask, the production time was extended to 226 h and the maximal antibiotic concentration was 76 mg/l. When scaling up the cultivation process to a bioreactor level, the production time was reduced to only 70h with a significant increase in both the cell growth and the antibiotic production. The maximal dry cell weights in the case of the controlled pH and uncontrolled pH cultures in the bioreactor were 22.4g/l and 14.2g/l, respectively. The corresponding maximal dry cell weight values did not exceed 7.25g/l with the shake flask cultures. The maximal values for Cyc A production were 144.72 and 131.4 mg/l for the controlled and uncontrolled pH cultures, respectively. It is also worth noting that a significant reduction was observed in both the dry cell mass and the antibiotic concentration after the Cyc A production phase, whereas the highest rate of antibiotic degradation was observed in the stirred tank bioreactor with an uncontrolled pH. Morphological characterization of the micromorphological cell growth (mycelial/pellet forms) was also performed during cultivation in the bioreactor.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.173-177
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• 1989

Cell density was gradually decreased as the dilution rate was increased under chemostat cultivation of HeLa cells. Maxium cell density was maintained at the dilution rate of 0.020 (1/h) which was far less than the wash-out rate of 0.050 (1/h), Maxium cell productivity of 2 (mL of cells/L/h)was obtained at the dilution rate of 0.030 (1/h) by showing the culture also required maintenance period at low dilution rates, whose result meant the deviation of continuous culture theroy. Methods of indirectly measuring cell density have been introduced to represent mammalian cell growth, which are packed cell volume and oxygen uptake rate, and these values showed good linear relationship with actual cell density by having correlation factor of 0.90. Theoretical maximum oxygen yield, $Y_{O2}^{max}$ and maintenance oxygen consumption rate, m$_{O2}$, were estimated as 4.1$\times$10$^5$ (cells/mmole $O_2$) and 10.71$\times$10$^{-9}$ (mmole $O_2$/cells/h) by employing oxygen yield model.

• Research in Plant Disease
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• v.23 no.1
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• pp.19-34
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• 2017

Recent worldwide demand for organic and sustainable agriculture products is driving the development of formulations of biopesticides effective in the field. Biopesticides have the benefit of environmentally-friendly qualities. However, biocontrol approaches largely have been ineffective in controlling plant pests in field conditions. Previously, we developed a cost-effective biocontrol formulation containing chitin and chitinase-producing biocontrol bacteria with field efficacy. This formulated product has successfully suppressed various plant diseases in the field conditions. In this review, we focus on ecological aspects and the potential mechanisms underpinning the success of chitinase-producing bacteria. In addition, we discuss the possibility on-site cultivation of the formulated products to further strengthen the approach as being farmer friendly and successful.

• Plant Resources
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• v.3 no.2
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• pp.110-117
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• 2000

The recycling method of enokitake cultural waste and the potentiality of second flush for enokitake were determined, because this fungus is not as prolific as the more commonly cultivated white rot fungi in the conversion of sawdust to mycelial mass. The mycelial growth of F. velutipes on several substrates, variously treated with rice bran was promoted at ratios of 10-20% (w/w) on all substrates, but suppressed at above ratios, although some difference was there. The mycelial densities generally increased correlated to the supplementation contents of rice bran. It could be concluded that F. velutipes preferred mild acidic to acidic conditions for mycelial growth, considering that the mycelial growth rate was highest on waste of pH 6.01, treated with 0.1 % Ca(OH)$_2$ and on populus mixed waste of pH 6.02, non treated. The ranges of substrate bulk densities, which was pertinent for mycelial linear growth were from B.D. (g/cc) 0.17 to 0.23 on waste and populus mixed waste all. The pertinent contents of rice bran supplementation in bottle cultivation was from 20 to 30% on waste and 20% on populus mixed waste, considering the requried duration for pinheading and fruiting yields. Standard bulk density for filling and utilizing the waste and populus mixed waste for commercial f. velutipes cultivation were B.D.(g/cc) 0.19 ~ 0.23, and 0.23~ 0.25, which could be conversed to 510~ 540g/900m1 and 520~ 570g/900m1, respectively, The second flush of F. velutipes was tried and the re-inoculation by sawdust and liquid spawn showed somewhat good results, indicating the potentiality of second crop and suggesting further research for it.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.242-250
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• 2016

Veterinary antibiotics (VAs) has been used to treat animal disease and to increase animal weight as growth promoter. However, abused usage of VAs can cause production of antibiotic resistance genes (ARGs) in the environment and additionally, residual of VAs in soil can be transferred into crops. Therefore, main objective of this research was to examine bioaccumulation of VAs in sprouts (red cabbage, Brassica Olearacea L. var. Capitata f. rubra and red radish, Raphanus sativus) with hydroponic method. Total of 7 VAs in 2 different classes of VAs (tetracyclcines: tetracycline, oxytetracycline, chlortetracycline, sulfonamides: sulfamethoxazole, sulfamethazine, sulfamethiazole, macrolides: tylosin) were evaluated and experiment was conducted with solid phase extraction (SPE)/high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS). Initial spiked concentration of 7 VAs was $5mg\;L^{-1}$ and cultivation period was 8 days. Result showed that growth of sprouts was inhibited about 23-27% when VAs was introduced. Amount of bioaccumulated VAs was also differed depending on class of VAs. The highest amount of bioaccmulated VAs was tetracycline and sulfamethoxazole in each class with a concentration of 4.05, $7.73mg\;kg^{-1}$ respectively. Calculated transfer ratio of VAs into crops was also ranged 0.38-54.27%. Overall, bioaccumulation of VAs in crops can be varied depending on crop species and class of VAs. However, further research should be conducted to verify bioaccumulation of VAs in crops in the soil environment.

• Journal of Forest and Environmental Science
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• v.26 no.3
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• pp.219-223
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• 2010

It has long been recognized that wild vegetation are sort of improving fitness. Many peoples are now ingesting them instead of the vegetables that are grown in green house. In this regard, Parasenecio firmus, which is considered to be one of the rare species in Korea, has been given a lot of attentions as edible green plants recently. Hence it may be necessary to provide the information people who want to commercially cultivate the plants. Regarding appropriate forest stands that are fit for the cultivation. Firstly, we collected the seeds from 4 natural habitats to find out how many seeds are fully matured in the natural conditions. The quality of the seeds collected were found to be very low. However, it appeared as clear differences when screened seeds were grown in covered seed beds over winter. In this case the germination rate of the seeds was 95%, indicating that there may be no difficulty for mass production of plantlets. Secondly, in the field of planting test in an appropriate cultivating site among 6 of forest stands, those in Pinus koraiensis stand were the highest in survival rate, but somewhat low with those in Quercus mongolica and broad-leaved stands. Thus, it was demonstrated that forest stands dominated with conifer like P. koraiensis are more appropriate for the cultivation of P. firums.