• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.477-482
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• 1998

In the aquaculture industry, a photobioreactor (Pbr) with high productivity is a prerequisite for mass production of Chlorella sp., a feeding fry for Rotifer (Brachinous plicatilis). To enhance the productivity of Chlorella sp., model Pbrs such as Cylinder type, Spherical surface type, Half-spherical surface type, Plate type, Raceway pond type and Water-wheel type Pbr with different values of surface area exposed to light/culture volume (S/V) were manufactured, and the maximum specific growth rate (${\mu}_{max}$) and productivity of Chlorella vulgaris 211-11b at $25^{\circ}C$, pH 7.0 and 12,000 lux were compared each other. The ${\mu}_{max}$ and productivity were not proportional to S/V. Among the 6 model Pbrs, Half-spherical surface type Pbr showed the highest ${\mu}_{max}$ and productivity as 2.206 ($day^{-1}$) and 0.247($g^{{\ell}-1}day^{-1}$).

• Journal of Plant Biology
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• v.24 no.1
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• pp.1-12
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• 1981

Phosphorus dynamics in terms of specific absorption rate, inflow and outflow rates. turnover rate, demand and supply, and utility index of a high yield Zea mays L. cv. Bokgyo field were evaluated using an analysis of successive production structures. The analysis was adopted for measuring quantitative changes in the population by stratified clip technique on every two weeks during the growing season. The seasonal trends of specific absorption rate (2. 4 mg P/g/day in maximum) and specific absorption efficiency (0. 03) closely correlated with that of relative growth rate of the population. The overall inflow and outflow of phosphorus was 3.41 g P/$m^2$/yr showing the maximum inflow of 2.99 g P/$m^2$/month in July. While the maximum phosphorus standing crop was 1.4 g P/$m^2$ showing the maximum turnover rate of 178% in late June. The accumulation of phosphorus along plant height declined monotonically in stems and roots but increased in foliage after heading. The proportions of the total annual demand of phosphorus were 24.4% for leaves, 22.5% for stems, 49.6% for fruits and 3.5% for roots. These demands were met with internal (18.2 %) and external (81.8 %) supplies. The seasonal highest phosphorus utility index was 1,091 in early June, while the average value was 655.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.11-19
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• 2000

In order to predict the performance of biological wastewater treatment plant, the kinetic parameters and stoichiometric coefficient must be known. The theories and experimental procedures for determining the biological kinetic parameters were discussed in this study. Respirometric analysis in the batch reactor was carried out for the experimental assessment of kinetic parameters. A simple procedure to estimate kinetic parameters of heterotrophs and autotrophs under aerobic condition was presented. The difficulties in the interpretation of COD and VSS measurements encouraged the conversion of respirometric data to growth data. Maximum specific growth rate, yield coefficient, half saturation constant and decay rate of heterotrophic biomass were obtained from OUR(Oxygen Uptake Rate) data. Maximum specific growth rate of autotrophic biomass was obtained from the increase of nitrate concentration. The aim of this paper is to estimate the kinetic parameters of heterotrophic and autotrophic biomass by means of the respirometric analysis of activated sludge behavior in the batch reactors. These procedures may be used for the activated sludge modeling with complex kinetic parameters.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.1-6
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• 2013

A fixed biofilm reactor system composed of anaerobic, anoxic(1), anoxic(2), aerobic(1) and aerobic(2) reactor was packed with synthetic activated ceramic (SAC) media and adopted to reduce the inhibition effect of low temperature on nitrification activities. The changes of nitrification activity at different wastewater temperature were investigated through the evaluation of temperature coefficient, volatile attached solid (VAS), specific nitrification rate and alkalinity consumption. Operating temperature was varied from 20 to $5^{\circ}C$. In this biofilm system, the specific nitrification rates of $15^{\circ}C$, $10^{\circ}C$ and $5^{\circ}C$ were 0.972, 0.859 and 0.613 when the specific nitrification rate of $20^{\circ}C$ was assumed to 1.00. Moreover the nitrification activity was also observed at $5^{\circ}C$ which is lower temperature than the critical temperature condition for the microorganism of activated sludge system. The specific amount of volatile attached solid (VAS) on media was maintained the range of 13.6-12.5 mg VAS/g media at $20{\sim}10^{\circ}C$. As the temperature was downed to $5^{\circ}C$, VAS was rapidly decreased to 10.9 mg VAS/g media and effluent suspended solids was increased from 3.2 mg/L to 12.0 mg/L due to the detachment of microorganism from SAC media. And alkalinity consumption was lower than theoretical value with 5.23 mg as $CaCO_3$/mg ${NH_4}^+$-N removal at $20^{\circ}C$. Temperature coefficient (${\Theta}$) of nitrification rate ($20^{\circ}C{\sim}5^{\circ}C$) was 1.033. Therefore, this fixed film nitrogen removal process showed superior stability for low temperature condition than conventional suspended growth process.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.756-761
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• 1996

Influence of acetic acid on xylitol production from xylose using Candida parapsilosis KFCC 10875 was investigated at the different concentrations of acetic acid. Acetic acid was totally consumed below 1.0 g/l of its concentration, whereas partially consumed above 3.0 g/l and remained in the medium during xylitol fermentation. Cell growth, xylose consumption, and xylitol production decreased when acetic acid concentration was increased. Specific growth rate of cell and specific consumption rate of xylose also decreased with increasing the concentration of acetic acid. However, the xylitol yield from xylose and specific production rate of xylitol were maximum at 1.0 g/l of acetic acid. The inhibitory effect of acetic acid on xylitol fermentation increased when pH was decreased.

• Journal of Life Science
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• v.14 no.2
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• pp.235-238
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• 2004

The possibility for developing multistage culture system to cultivate larvae by computer simulation with basic experiments was investigated. This culture system was composed of 3 stages. At the 1st stage, Chlorella sp. were cultivated and at 2nd stage Chlorella sp. were supplied to rotifer (Brachionus plicatilis), and rotifer were supplied to larvae at the 3rd stage. In this study, Chlorella sp. were cultivated by batch culture to search for the possibility of continuous feeding to rotifer at 2 nd stage. The maximum specific growth rate ($\mu$$_{max}$) of Chlorella sp. at the logarithmic phase was 0.56 [1/day]. Rotifer was cultivated by fed-batch culture at the feeding rate of Chlorella sp., $10^3$, $10^4$, $10^{5}$ and $10^{6}$ [cells/rotiferㆍh] to search for the relation between the feeding rate of Chlorella sp. and the growth rate of rotifer. As the results, the minimum feeding rate of Chlorella sp. was 2.8 ${\times}$ $10^4$ [cells/rotiferㆍday] in the multistage culture system, then the change of rotifer concentration at 2nd stage was simulated by computer. The required amount of rotifer for the growth of larvae was also increased as the growth of larvae. On the 9th day of the culture, the rotifer uptake rate of larvae was 250 [cells/rotiferㆍday]. Based on these basic experiments and results, It was suggested that the possibility of multistage culture system to cultivate larvae with continuous feeding of Chlorella sp. and rotifer.r.

• ALGAE
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• v.29 no.2
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• pp.137-152
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• 2014

Mixotrophic protists play diverse roles in marine food webs as predators and prey. Thus, exploring mixotrophy in phototrophic protists has emerged as a critical step in understanding marine food webs and cycling of materials in marine ecosystem. To investigate the feeding of newly described mixotrophic dinoflagellate Ansanella granifera, we explored the feeding mechanism and the different types of species that A. granifera was able to feed on. In addition, we measured the growth and ingestion rates of A. granifera feeding on the prasinophyte Pyramimonas sp., the only algal prey, as a function of prey concentration. A. granifera was able to feed on heterotrophic bacteria and the cyanobacterium Synechococcus sp. However, among the 12 species of algal prey offered, A. granifera ingested only Pyramimonas sp. A. granifera ingested the algal prey cell by engulfment. With increasing mean prey concentration, the growth rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but became saturated at a concentration of $434ngCmL^{-1}$ (10,845 cells $mL^{-1}$). The maximum specific growth rate (i.e., mixotrophic growth) of A. granifera feeding on Pyramimonas sp. was $1.426d^{-1}$, at $20^{\circ}C$ under a 14 : 10 h light-dark cycle of $20{\mu}Em^{-2}s^{-1}$, while the growth rate (i.e., phototrophic growth) under similar light conditions without added prey was $0.391d^{-1}$. With increasing mean prey concentration, the ingestion rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but slightly at the concentrations ${\geq}306ngCmL^{-1}$ (7,649 cells $mL^{-1}$). The maximum ingestion rate of A. granifera feeding on Pyramimonas sp. was 0.97 ng C $predator^{-1}d^{-1}$ (24.3 cells $grazer^{-1}d^{-1}$). The calculated grazing coefficients for A. granifera feeding on co-occurring Pyramimonas sp. were up to $2.78d^{-1}$. The results of the present study suggest that A. granifera can sometimes have a considerable grazing impact on the population of Pyramimonas spp.

• Food Science of Animal Resources
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• v.29 no.3
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• pp.289-295
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• 2009

The aim of this research was to develop predictive models for the growth of spoilage bacteria (total viable cells, Pseudomonas spp., and lactic acid bacteria) on frankfurters and to estimate the shelf-life of frankfurters under aerobic conditions at various storage temperatures (5, 15, and $25^{\circ}C$). The primary models were determined using the Baranyi model equation. The secondary models for maximum specific growth rate and lag time as functions of temperature were developed by the polynomial model equation. During 21 d of storage under various temperature conditions, lactic acid bacteria showed the longest lag time and the slowest growth rate among spoilage bacteria. The growth patterns of total viable cells and Pseudomonas spp. were similar each other. These data suggest that Pseudomonas spp. might be the dominant spoilage bacteria on frankfurters. As storage temperature increased, the growth rate of spoilage bacteria also increased and the lag time decreased. Furthermore, the shelf-life of frankfurters decreased from 7.0 to 4.3 and 1.9 (d) under increased temperature conditions. These results indicate that the most significant factor for spoilage bacteria growth is storage temperature. The values of $B_f$, $A_f$, RMSE, and $R^2$ indicate that these models were reliable for identifying the point of microbiological hazard for spoilage bacteria in frankfurters.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.259-270
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• 2020

Listeria monocytogenes is a gram-positive, facultative anaerobe food pathogen responsible for the listeriosis that mostly occurs during the low-temperature storage of a cold cut or dairy products. To understand the systemic response to a wide range of growth temperatures, L. monocytogenes were cultivated at a different temperature from 10℃ to 42℃, then whole cell proteomic analysis has been performed both exponential and stationary cells. The specific growth rate increased proportionally with the increase in growth temperature. The maximum growth rate was observed at 37℃ and was maintained at 42℃. Global protein expression profiles mainly depended on the growth temperatures showing similar clusters between exponential and stationary phases. Expressed proteins were categorized by their belonging metabolic systems and then, evaluated the change of expression level in regard to the growth temperature and stages. DnaK, GroEL, GroES, GrpE, and CspB, which were the heat&cold shock response proteins, increased their expression with increasing the growth temperatures. In particular, GroES and CspB were expressed more than 100-fold than at low temperatures during the exponential phase. Meanwhile, CspL, another cold shock protein, overexpressed at a low temperature then exponentially decreased its expression to 65-folds. Chemotaxis protein CheV and flagella proteins were highly expressed at low temperatures and stationary phases. Housekeeping proteins maintained their expression levels constant regardless of growth temperature or growth phases. Most of the growth related proteins, which include central carbon catabolic enzymes, were highly expressed at 30℃ then decreased sharply at high growth temperatures.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.362-372
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• 2010

In order to understand what leads to the appearance of harmful Chattonella algae in the Yeosu coastal waters of Korea, we measured environmental parameters every week at one station from May to November, 2006, and April to October, 2007. Four species of Chattonella appeared during the monitoring period: C. antiqua, C. globosa, C. marina and C. ovata. The range of water temperature and salinity were $15.0-27.9^{\circ}C$ and 17.6~33.0 psu, respectively, when Chattonella appeared, and their maximum cell density (4,840 cells/L) was at $27.1^{\circ}C$ and 33.0 psu. During the monitoring periods, the range of dissolved inorganic nitrogen (DIN), phosphate (DIP) and chlorophyll $\alpha$ (Chl-$\alpha$) concentrations in surface waters were $1.20-52.23\;{\mu}M$ ($8.59{\pm}8.97\;{\mu}M$), $0.03-1.56\;{\mu}M$ ($0.47{\pm}0.31\;{\mu}M$) and $0.45-31.12\;{\mu}g/L$ ($3.58{\pm}4.77\;{\mu}g/L$), respectively. Chattonella occurred at low cell density when the Chl-$\alpha$ concentration increased because of supplied nutrients, whereas their cell density increased during the periods of rapid decrease in Chl-$\alpha$. The results of growth experiments based on batch culture showed that the half saturation constant ($K_s$) of C. antiqua on ammonium (${NH_4}^-$), nitrate (${NO_3}^-$) and phosphate (${PO_4}^{2-}$) were $3.89{\mu}M$, $5.01\;{\mu}M$ and $0.63\;{\mu}M$, respectively. These Ks values are higher than those reported for diatoms and other flagellates at the DIP concentration (average $0.47{\mu}M$) of Yeosu coastal waters. Although the maximum specific growth rate (${\mu}_{max}$) of C. antiqua was lower than diatoms, it was higher than those of other flagellates. Therefore, our results indicate that the DIP level in the study area was too low to support Chattonella blooms, although Chattonella species have physiological characteristics that enable them to grow more rapidly than other flagellates when nutrient levels are higher than their $K_s$.