• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.868-877
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• 2013

To understand the effects of marine environmental and meteorological parameters on laver Porphyra yezoensis production at Nakdong River Estuary, we analyzed marine environmental (water temperature, salinity, nutrients, etc.) and meteorological properties (air temperature, wind speed, precipitation, sunshine hours) with yearly and monthly variations in laver production over 10 years (2003-2013). Air and water temperature, wind speed, sunshine hours and precipitation were major factors affecting yearly variability in laver production at the Nakdong River Estuary. Lower air and water temperatures together with higher levels of nutrients and sunshine and stronger wind speeds resulted in higher laver harvests. Salinity and nitrogen did not show clear correlations with laver production, mainly due to the plentiful supply of nitrogen from river discharge and the low frequency of environmental measurements, which resulted in low statistical confidence. However, environmental factors affecting monthly laver production were related to the life cycle (culturing stage) of Porphyra yezoensis and were somewhat different from factors affecting annual laver production. In November, a young laver needs lower water temperatures for rapid growth, while a mature laver needs much stronger winds and more sunshine, as well as lower temperatures for massive production and effective photosynthesis, mostly in December and January. However, in spring (March), more stable environments with fewer fluctuations in air temperature are needed to sustain the production of newly deployed culture-nets ($2^{nd}$ time culture). These results indicate that rapid changes in weather and marine environments caused by global climate change will negatively affect laver production and, thus, to sustain the yield of and predict future variability in laver production at the Nakdong River estuary, environmental variation around laver culturing farms needs to be monitored with high resolution in space and time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.3
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• pp.379-385
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• 2022

This study was conducted to evaluate the dietary supplementation of citrus byproduct (CBP) on the growth performance, feed utilization, and innate immune responses of juvenile olive flounder Paralichthys olivaceus under low water temperatures (11-15℃). Dietary L-ascorbyl-2-polyphosphate was replaced with graded CBP levels at 0 (Con), 25 (CBP25), 50 (CBP50), 75 (CBP75), and 100% (CBP100). Triplicate groups of juvenile olive flounder were handfed with one of the diets twice a day for 42 days. The growth performance and feed utilization of fish fed with diet containing levels of CBP75 or CBP100 increased significantly compared to those of fish with fed Con. Dietary CBP supplementation increased the protein efficiency ratio in fish. There was no significant differences in innate immune responses between groups, even though CBP supplementation tended to increase. These findings indicate that CBP could be used as a vitamin C source and improve the growth performance of juvenile olive flounder under low water temperatures.

• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.209-218
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• 1987

Leptospira interrogans, the causative organism of leptospirosis, is characterized by a fine helical morphology, and the helix is almost always right-handed. However, one of the striking features of recent isolates of L. interrogans in Korea was the heterogeneity in their morphology. Even under optimal culture conditions($30^{\circ}C$, EMJH medium), rods, spiral forms with right or left-handed helices, and even spherical forms of L. interrogans were present. Although the literature notes the presence of left-handed helices, long rods, and spherical forms in cultures of L. interrogans isolates, little is known about the cause of this morphologic heterogeneity. In an attempt to answer this question, this study was initiated to examine the effects of culture conditions, especially temperature and medium, on the morphology of L. interrogans. Four temperatures($5^{\circ}C$, $15^{\circ}C$, $30^{\circ}C$, and $37^{\circ}C$) and two types of media(Fletcher and EMJH) were used; one strain from Korean isolates and L. interrogans serovar canicola obtained from the Pasteur Institute(Paris, France) were employed throughout the study. The findings are as follows: 1. The L. interrogans isolated in Korea(UM-19) had a larger cell diameter($0.25{\sim}0.30\;{\mu}m$: $0.10{\sim}0.15\;{\mu}m$), and helix diameter($0.10{\sim}0.60\;{\mu}m$: $0.10{\sim}0.15\;{\mu}m$) than that obtained from the Pasteur Institute, but they varied in their distances between the helices($0.31{\sim}1.00\;{\mu}m$: $0.50{\sim}0.70\;{\mu}m$). 2, When UM-19 was grown at $37^{\circ}C$ after months or longer preincubation at $5^{\circ}C$ or $15^{\circ}C$, the majority of the organisms were spiral forms; however, they became rods when subcultured at $30^{\circ}C$ or $37^{\circ}C$. No significant morphological differences were found between Fletcher and EMJH media. 3. When L. interrogans serovar canicola was subcultured more than ten times at $37^{\circ}C$, some of the organism lost their motility as well as the hooks at either one or both ends, but only in Fletcher medium. The number of variants increased with the frequency of subculturing. These findings suggested that L. interrogans strain (UM-19) is different, in their morphology, from that of the Pasteur Institute, and its various morphologies may represent stages of the life cycle and vary with incubation temperature.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.125-130
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• 2005

The growth and phosphatase (phosphomonoesterase) activity of Chroococcidiopsis culture isolated from the cryptoendoliths of the Antarctic were compared with a similar isolate from the Arizona hot desert. Such cyanobacteria living inside rocks share several features with the immobilized cells produced in the laboratory. This study has relevance because the availability of phosphorus is a key factor influencing the growth of these cyanobacteria in nature, in such unique ecological niches as the hot and cold deserts. Phosphatase activity therefore is of particular importance for these organisms if they are to survive without any other source of phosphorus availability. Also, there is paucity of knowledge regarding this aspect of study in cyanobacterial cultures from these extreme environments. The salient feature of this study shows the importance of specific pH and temperatures for growth and phosphatase activity of both cultures, although there were marked differences between the two isolates. The pH and temperature optima for growth and phosphatase activity (PMEase) of Chroococcidiopsis 1 and 2 were 9.5, $240^{\circ}C$ and 8.5, $40^{\circ}C$ respectively. The $K_m and V_max$ values of cultured Chroococcidiopsis 1 showed lower affinity of PMEase for the substrate compared to the enzyme affinity of the same organism when found within the rocks; Chroococcidiopsis 2 and Arizona rocks containing the same alga however showed similar affinity of PMEase for the substrate. An interesting observation was the similarity in response of immobilized Chroococcidiopsis 1 culture and the same organism in the Antarctic rocks to low light and low temperature stimulation of PMEase. This thermal response seems to be related to the ability of the immobilized Antarctic isolate and the rocks to either cryoprotect the PMEase or undergo a change to save the enzyme from becoming nonfunctional under low temperatures. The free cells of Chroococcidiopsis 1 culture however did not show such responses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.215-222
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• 1994

Kang-Nung sik-hae is a traditional Korean fermented fish product which has remained in existence in Kang-Nung district. In order to preserve the traditional culture of Kang-Nung sik-hae and develop it as a commercial product, the property changes of sik-hae were investigated at different fermentation temperatures and periods. The chemical changes during the fermentation of squid(Todarodes pacificus) sik-hae were studied at different fermentation temperatures and periods. The amounts of proximate compositions and salinity did not change significantly at all fermentation temperatures and periods. The value of pH decreased with increasing storage period at all fermentation temperatures except at $5^{\circ}C$, whereas that of lactic acid at all fermentation temperatures increased. The amount of total arginine increased slightly up to 10-day of storage and decreased after that. The amount of $NH_2-N$ increased rapidly up to 15-day of storage at all temperatures and increased slightly after that. The amount of TMAO decreased significantly at $15^{\circ}C\;and\;20^{\circ}C$ and slightly at $5^{\circ}C\;and\;10^{\circ}C$, whereas that of TMA increased significantly at $20^{\circ}C$ up to 5-day of storage and decreased slightly after that. At all experimental temperatures except $5^{\circ}C$, the amount of TMA increased or fluctuated in proportion to the increase in fermentation periods. Inosine and hypoxanthine were the main components of nucleotides and their related compounds during the fermentation of sik-hae. Summarizing the above results, the optimum fermentation period of sik-hae was concluded to be 15-days at all experimental temperatures except $5^{\circ}C$.

• The Plant Pathology Journal
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• v.17 no.4
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• pp.216-221
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• 2001

Dieback of pine branches or twigs with brown needles occurs most commonly on Pinus species after severe winter in Korea. In this study, Cenangium ferruginosum was isolated from infected stems, branches, and twigs of Pinus koraiensis (C1), P. densiflora (C2), and P. thunbergii (C3). Morphological and cultural characteristics of the isolates were than compared. There were no significant differences in the morphological characteristics of conidia and ascospores produced by the three isolates. However, cultural differences were observed among the isolates. Optimum temperatures for mycelial growth of C1, C2, and C3 were 15, 20, and $20^{\circ}$, respectively. C1 produced a few conidia and no ascospores, while C2 and C3 produced abundant ascospores and conidia. While optimum temperatures for mycelial growth ranged from 15 to $20^{\circ}$, mycelial growth was also relatively good at lower temperatures of 5-$10^{\circ}$. Conidiomata and conidia were produced on MSA (malt extract soya peptone agar) after 25-30 days of incubation in the dark at $15^{\circ}$. Apothecia were produced by altering culture condition from 15 to $20^{\circ}$, and incubating for 35-60 more days. Optimum temperature for ascospore and conidium germination was $20^{\circ}$. RAPD analysis revealed that there was high similarity of 0.78 between C2 and C3, and low similarity of 0.31 between C2 or C3 and C1.

• Journal of Ecology and Environment
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• v.38 no.1
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• pp.67-74
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• 2015

Three strains of the green microalga Botryococcus braunii (JJS, KCM, and KJD) were isolated from different water bodies in Korea and grown as batch cultures in the laboratory. The effects of different growth media and temperatures on the growth rate were investigated, as well as the effect of temperature on the total lipid content and lipid profile. All three strains had the highest growth rates in BG-11 medium and at $25^{\circ}C$. Maximal lipid production ($gL^{-1}$) was at $30^{\circ}C$ in the JJS strain and at $25^{\circ}C$ in the KCM and KJD strains. However, all the three strains produced the greatest percent dry weight of total lipids at $15^{\circ}C$ and had the lowest percent dry weight of total lipids at $25^{\circ}C$. In general, oleic acid, linolenic acid, and behenic acid were the most common fatty acids in all three strains. However, the three strains varied considerably in their fatty acid profiles at different culture temperatures.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.109-115
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• 2023

Interspecific hybridization is a beneficial strategy in aquaculture. In this study, diploid hybrids were produced through interspecies hybridization of flounder Platichthys bicoloratus ♀ × starry flounder P. stellatus ♂, which became commercial within a year. These hybrids exhibited an advantage in growth ability, with female hybrids growing twice as large as males at 11 months. Furthermore, hybrid flounders exhibited faster growth rates than starry flounders and reciprocal hybrids. The average growth rate of hybrids was 1.37 and 1.18 times greater than that of starry flounder and reciprocal hybrids at 5.5 months, respectively; Additionally, feed efficiency was 1.21 and 1.10 times higher than that of the experimental groups. The experiments were conducted at five temperatures to determine the optimal fry production method. Six weeks of culture resulted in a significant temperature effect, with maximum growth at 27℃. However, over 90% of the males occurred in the groups at temperatures above 24℃. Therefore, the optimum temperatures for survival, growth, condition factor and frequency of the best-sized fingerling at 13 weeks of age were estimated at 21℃. Thus, hybrid flounders are of great potential for use in the flounder aquaculture industry.

• Food Science of Animal Resources
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• v.42 no.2
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• pp.252-265
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• 2022

Kocuria salsicia can survive in extreme environments and cause infections, including catheter-related bacteremia, in humans. Here, we investigated and evaluated the characteristics of nine K. salsicia strains (KS1-KS9) isolated from cheese brine from a farmstead cheese-manufacturing plant in Korea from June to December, 2020. Staphylococcus aureus American Type Culture Collection (ATCC) 29213 was used as a positive control in the growth curve analysis and biofilm-formation assays. All K. salsicia isolates showed growth at 15% salt concentration and temperatures of 15℃, 25℃, 30℃, 37℃, and 42℃. KS6 and KS8 showed growth at 5℃, suggesting that they are potential psychrotrophs. In the biofilm-formation analysis via crystal violet staining, KS6 exhibited the highest biofilm-forming ability at various temperatures and media [phosphate buffered saline, nutrient broth (NB), and NB containing 15% sodium chloride]. At 25℃ and 30℃, KS3, KS6, and KS8 showed higher biofilm-forming ability than S. aureus ATCC 29213. The antimicrobial resistance of the isolates was evaluated using the VITEK^® 2 system; most isolates were resistant to marbofloxacin and nitrofurantoin (both 9/9, 100%), followed by enrofloxacin (7/9, 77.8%). Five of the nine isolates (5/9, 55.6%) showed multidrug resistance. Our study reports the abilities of K. salsicia to grow in the presence of high salt concentrations and at relatively low temperatures, along with its multidrug resistance and tendency to form biofilms.

• Journal of the East Asian Society of Dietary Life
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• v.27 no.3
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• pp.348-363
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• 2017

We analyzed the mixed culture characteristics of isolated brewing fungi obtained from Korean traditional nuruk for their development as fermentation starters. In a previous study, we selected appropriate fungi strains based on their large fungi bodies and strong enzyme activities. These fungi strains were mixed cultured under various combination of ratios, pHs and temperatures. As a result, total acidities of R. delemar mixed culture media were higher than those of A. oryzae cultured at $20^{\circ}C$ and $37^{\circ}C$. The pHs of A. luchuensis 34-1 and A. oryzae 37-7 as well as R. delemar 58-8 and A. oryzae 37-7 mixed culture media gradually increased with the culture period. On the contrary, total acidities of the mixed culture media gradually decreased. ${\alpha}-Amylase$ activities of R. delemar 26-4 and R. oryzae 82-7 mixed culture media were strong at $20^{\circ}C$ and pH 4, glucoamylase activities of R. delemar 58-8 and A. oryzae 37-7 were strong at $37^{\circ}C$, pH 3 and 1:2 ratio, and acidic protease activities of R. delemar 26-4 and A. oryzae 78-5 were strong at $20^{\circ}C$, pH 4 and 1:4 ratio. This study provides the optimal mixed culture conditions for fermentation starters based on changes in pH and total acidity, favorable enzyme activities, and fungi varieties.