• Korean Journal of Food Science and Technology
• /
• v.37 no.6
• /
• pp.951-956
• /
• 2005

Selection of oxygen-tolerant strains and elucidation of their oxygen tolerance mechanism were crucial for effective use of bifidobacteria. Oxygen-tolerant bifidobacteria were able to significantly remove environmental oxygen (oxygen removal activity) as compared to oxygen-sensitive strains. Most oxygen removal activity was inhibited by heat treatment and exposure to extreme pH (2.0) of bifidobacterial cell. NADH oxidase was major enzyme related to oxygen removal activity. Oxygen-tolerant bifidobacteria possessed high NADH peroxidase activity level to detoxify $H_2O_2$ formed from reaction of NADH oxidase. Addition of oxygen to anaerobic culture broth significantly increased activities of HADH oxidase and NADH peroxidase within 1hr and rapid increment of oxygen concentration was prevented. Results showed NADH oxidase and NADH peroxidase of oxygen-tolerant bifidobacteria played important roles in elimination of oxygen and oxygen metabolite $(H_2O_2)$.

• KSBB Journal
• /
• v.17 no.1
• /
• pp.26-32
• /
• 2002

The aerobic bacterium Xanthomonas campestris was cultivated continuously in a three-phase fluidized bed bioreactor to produce extracellular polysaccharide xanthan, Fluidized particles of 8.0 mm glass beads were used for disintegrating the large air bubbles even at high viscosities to improve the gas-liquid oxygen transfer rate. Xanthin productivity [kg xanthan/kg cell dry mass·h] and molecular weight increased, with dilution rate in the continuous xanthan fermentations. The specific xanthan productivities were not limited by the oxygen transfer rate and were much higher in the continuous cultivations than those predicted by the results of the batch xanthan fermentations.

• Horticultural Science & Technology
• /
• v.29 no.1
• /
• pp.23-28
• /
• 2011

Experiments were conducted to investigate the optimum concentration of the nutrient solution in strawberry 'Sulhyang' with hydroponics in relationship between root activity and nutrient concentrations. Nutrient solutions for strawberry, made by Yamazaki, were supplied EC 0.5, 1.0, 2.0 $dS{\cdot}m^{-1}$ during experiment period. Growth of shoot and root of strawberries grown in visible plastic pot was observed during experiment. Petiole length was longest in plants grown in EC 1.0 $dS{\cdot}m^{-1}$, followed by 2.0 and 0.5 $dS{\cdot}m^{-1}$. Leaf width was longest in plants grown in EC 1.0 $dS{\cdot}m^{-1}$, followed by 0.5 and 2.0 $dS{\cdot}m^{-1}$. Fruit length, fruit diameter, fruit weight and yield were higher in EC 0.5 and 1.0 $dS{\cdot}m^{-1}$ than 2.0 $dS{\cdot}m^{-1}$ treatment but, soluble solids of the fruit did not show statistical differences among treatments. Shoot dry weight was heaviest in EC 1.0 $dS{\cdot}m^{-1}$, followed by 0.5 and 2.0 $dS{\cdot}m^{-1}$. Root dry weight was heavier in EC 0.5 and 1.0 $dS{\cdot}m^{-1}$ but significantly light in 2.0 $dS{\cdot}m^{-1}$. pH of the drainage solution was elevated in low nutrient concentration and lowered in high concentration. Also root activity was high in low nutrient concentration and low in high concentration. As a result, the optimum EC for strawberry 'Sulhyang' was EC 1.0 $dS{\cdot}m^{-1}$ in this experiment. It was confirmed that there was high relationship between root activity and pH of drainage solution. This result will be utilized as an indicator for strawberry hydroponics.

• Journal of Bio-Environment Control
• /
• v.22 no.4
• /
• pp.385-391
• /
• 2013

In this study, the availability of slurry composting and biofiltration (SCB) solution as an alternative for synthetic nutrient solution was determined by monitoring the growth, fruit yield, and fruit quality of cherry tomato (Solanum lycopersicum L. 'Unicon'). Treatments for nutrient solution were consist of SCB 1/2N, 1N, 2N, and commercial nutrient solution 1N (CNS 1N) based on nitrogen concentration (218.32 $mg{\cdot}L^{-1}$) of cherry tomato nutrient solution (control 1N). All nutrient solution including SCB solution (440~520 mL per day) was supplied to rock wool medium using a timer. After 31 days of transplanting, fresh and dry weights of shoots, leaf area, plant height, stem diameter, SPAD value and number of node were measured. After measuring growth characteristics of tomato plants, total fruit yield, ratio of marketable fruit yield, fruit weight, total soluble solids content, total acidity, total phenolic concentration, and antioxidant capacity were determined once a week for 7 weeks. As a result, among the SCB treatments, SCB 1/2N was similar to control 1N and CNS 1N in terms of fresh and dry weights of shoots, leaf area, stem diameter, number of node, and SPAD value. Increased N concentration of SCB inhibited the growth of tomato plants. Total fruit yield of SCB 1/2N was 47% of that of control 1N which showed the best result. Percentage of marketable fruit yield in SCB 1/2N was about 58%. Soluble solids contents, total acidity, total phenolic concentration and antioxidant capacity was the highest in SCB 2N and the other treatments were not shown any difference. Blossom-end rot rarely occurred in control 1N and CNS 1N while SCB treatments without Ca induced the physiological disorder of 7~19%. In conclusion, SCB 1/2N was good for the vegetative growth of cherry tomato plants but reduced yield and quality of fruit compared with control 1N and CNS 1N. Thus, it is possible to apply SCB solution to grow cherry tomato plants hydroponically but in the consideration of fruits yield and quality additional supply of several minerals would be required.

• KSBB Journal
• /
• v.16 no.5
• /
• pp.516-522
• /
• 2001

The large-scale production of antibiotics by filamentous mycelial organism requires and adequate supply of dissolved oxygen. In terms of productivity, it means that oxygen transfer is the rate-limiting step. Therefore, the oxygen transfer coefficients(K$\_$L/A) were determined in a broth involving a filamentous mycelial organism such as Streptomyces avermitilis for use in fermentations. To determine (K$\_$L/A) inn a stirred vessel, a great deal of effort is required to provide all the cells with a sufficient oxygen supply. To overcome the oxygen limitation in a batch culture, a fed-batch culture was applied to control the growth rate by an intermittent supply of nutrients. Thus, it was possible to maintain a suitable dissolved oxygen concentration at a low agitation rate. The optimal agitation speed was 350 rpm at low cell concentrations (below 7 g/L) by considering the efficiency of agitation and shear stress. The (K$\_$L/A) was found to decrease from 64.26 to 29.21h.$\^$-1/ when the biomass concentration was increased from 9.82 to 12.06 g/L. In addition, and increase in viscosity was also observed during the growth phase. By comparing the (K$\_$L/A) values for the various agitation and aeration rates, it was found that the effect of an increase in (K$\_$L/A) by aeration was reduced dramatically at high biomass concentrations. However, this effect was not observed when altering the agitation rate. This suggests that controlling the dissolved oxygen concentration by altering the agitation rate was more efficient than increase the aeration rate.

• Microbiology and Biotechnology Letters
• /
• v.30 no.4
• /
• pp.305-311
• /
• 2002

Acetyl xylan esterase gene (AXE) from Aspergillus ficuum was cloned and its Pichia expression plasmid, pPICZ$\alpha$C-AXE (4.6 kb), was constructed, in which the AXE gene was under the control of the AOXI promoter and connected downstream of mating factor u-1 signal sequence. The plasmid linearized by Sacl was integrated into the 5'AOXI region of the chromosomal DNA of P. pastoris. In the flask batch culture of P. pastoris transformant on methanol medium, the cell concentration and total AXEase activity reached at 6.0 g-dry cell weight/1 and 77 unit/ml after 36 h cultivation, respectively. In the fed-batch culture employing the optimized methanol and histidine feeding strategy, the cell concentration and total AXEase activity were significantly increased to about 97 g-dry cell weight/1 and 930 unit/ml. Most of AXEase activity (>90%) was found in the extracellular medium and the majority of extracellular protein (>80%) was AXEase enzyme (33.5 kDa). This result means that about 9.8 g/1 of AXEase protein was produced in the extracellular medium.

• Development and Reproduction
• /
• v.11 no.3
• /
• pp.263-272
• /
• 2007

Contrast to mouse where its in vitro maturation rates are high without specific supplements or presence of the cumulus cells, there are some species, such as porcine, where its in vitro oocyte maturation rates are still very low. This comparative study was conducted to investigate the role of malate dehydrogenase(Mor2) during oocyte maturation by RNAi in the mouse and porcine. The Mor2 double-stranded RNA(dsRNA) was prepared speciesspecifically and microinjected into the cytoplasm of denuded germinal vesicle(GV) oocytes. Oocytes were cultured for 48 h(porcine) and 16 h(mouse) in M199 with 10% porcine follicular fluid, pyruvate, p-FSH, EGF, cystein, and estradiol-$17{\beta}$. We measured changes in oocyte morphology, maturation rates and mRNA levels after Mor2 RNAi. We confirmed gene sequence-specific knock down of Mor2 mRNA in both species after Mor2 RNAi. In contrast to our previous finding that mMor2 RNAi resulted in GV arrest in the mouse, we found that pMor2 RNAi resulted in MI arrest in denuded porcine oocytes(58%), but developed to MII(84.4%) in COCs. To determine whether this difference between mouse and porcine RNAi is due to differences in culture media, we cultured mouse oocytes in the M199 media for 16 h after mMor2 RNAi. Mouse oocytes were developed to MII stage(62%) and there was no statistical difference compared to that of non-injected(76.8%) and buffer-injected(73.3%) control groups. Therefore, we concluded that the mouse and porcine oocytes are having different metabolic systems in relation to malate dehydrogenase for oocyte maturation. This could be a basis for differences in maturation rates in vitro in two species. Further scrutinized studies on the metabolic pathways would led us in finding better culture system to improve oocyte maturation rates in vitro, especially in more challenging species like the porcine.

• Horticultural Science & Technology
• /
• v.28 no.6
• /
• pp.973-979
• /
• 2010

The objective of this study was to determine the effect of electrical conductivity (EC) of nutrient solution on the growth, nutrient uptake of potted kalanchoe plants ($Kalanchoe$ $blossfeldiana$ 'New Alter') and the nutrient accumulation at the growing media with growth stage in ebb and flow subirrigation systems. Significant differences in leaf area, plant height, and dry weight of the plants were found among the different ECs of nutrient solution of 0.8, 1.6, 2.4, and $3.2dS{\cdot}m^{-1}$. Particularly the difference in plant growth became significantly greater from 5 weeks after treatment. The overall growth was the highest at EC $1.6dS{\cdot}m^{-1}$. Leaf area, plant height, and dry weight were maintained higher when EC increased to $2.4dS{\cdot}m^{-1}$, but rapidly decreased after EC $3.2dS{\cdot}m^{-1}$. The uptake of NO3-N was the greatest while that of $Mg^{2+}$ was the lowest at EC $1.6dS{\cdot}m^{-1}$, even though small differences were found among macro elements. The EC at the top layer of the growing media was 1 to 3 times higher than that at the bottom layer. Nutrient accumulation was accelerated in both the top and bottom layers with growth stage. At EC $3.2dS{\cdot}m^{-1}$, the growth of the plants was suppressed due to higher nutrient accumulation at the growing media. From the results, the strength and composition of nutrient solution should be determined by considering nutrient accumulation at the growing media in addition to EC of nutrient solution in ebb and flow subirrigation systems.

• The Korean Journal of Blood Transfusion
• /
• v.23 no.2
• /
• pp.115-126
• /
• 2012

Background: Umbilical cord (UC) is a promising source of mesenchymal stromal cells (MSCs). We compared the characteristics of MSCs from cryopreserved UC with those from fresh tissues, and demonstrated the possibility of UC cryopreservation for acquisition of MSCs from cryopreserved UC. Methods: Each UC was sliced into two types ($1{\sim}2mm^3$ vs. 0.5 cm), and cryopreserved in liquid nitrogen using different media (autologous cord blood plasma, aCBP vs. RPMI 1640). A fresh aliquot of $1{\sim}2mm^3$-sized UC was used as control tissue. After one week, the cryopreserved tissues were thawed and cultured. For the 0.5 cm UC, a slicing step into $1{\sim}2mm^3$ was needed. Cell count, viability, proliferative activity, and surface antigens were determined from harvested MSCs. Several growth factors (EGF, IGF-1, PDGF, TGF-${\beta}$, bFGF, and VEGF), were measured from the culture supernatant. Results: Eleven UC were enrolled in the study. Efficiencies of obtaining MSCs were higher in cryopreserved UC using RPMI 1640, compared with use of aCBP; the same result was observed for 0.5 cm sized UC, compared with $1{\sim}2mm^3$ sized UC. No difference in proliferative activity was observed between MSCs from fresh and cryopreserved UC. The amount of growth factors in culture supernatant using RPMI 1640 was larger than that of fresh tissues. Conclusion: We obtained growth factors from the supernatant as well as MSCs from cryopreserved UC. As with a cord blood bank, in the future, cryopreservation of UC for acquisition of both MSCs and growth factors would be possible in a time of need.

• Korean Journal of Animal Reproduction
• /
• v.19 no.4
• /
• pp.323-329
• /
• 1996

In vitro cultrue systems for the growth of sma-II oocytes and for meiotic maturation are expected to provide a new source of a large population of oocytes as well as assistance in basic physiological studies of oogenesis. Mouse oocytes mid-growth phase can complete grovvth and acquire full developmental capacity in vitro. On the other hand, growing pig oocytes need some other factors. FSH at a low concentration maintains the viability of both oocytes and granulosa cells, and hypoxanthine promotes the meiotic competence of the oocytes during culture period. Considerable improvement in the culture systems for growth of pig oocytes, suggested from mouse studies, and for oocyte maturation could help to develop this technology in larger species.