• Korean Journal of Microbiology
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• v.29 no.6
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• pp.371-379
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• 1991

Effects of freshwater red tide of Peridinium bipes (dinoflagellate) in August of 1991 on the carbon flux through the microbial loop were studied in Soyang Reservoir. Chlorophyll a and primary production, bacterial production in red tide area were 22, 18 and 400 times higher, respectively, than other sites. Phytoplandton biomass comprised 97% and 20% of food source of zooplankton grazing within and without red tide, respectively. The percent bacterial production supported by phytoplankton exudate was 14% within red tide and >100% without red tide. In laboratory experiments, more than 85% organic carbon of Peridinium biomass was released or degraded by heterotrophic bacteria within 14 days. As results of red tide of Peridinium with sudden influx of organic carbon in water column, the main food source of zooplankton and dependency of bacteria on phytoplankton exudate were changed. Therefore, the relative importance of microbial loop to grazing food web was changed.

• Ocean Science Journal
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• v.42 no.4
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• pp.247-254
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• 2007

Marine bacteria, actionmycetes and fungal strains were isolated from continental slope sediment of the Bay of Bengal and studied for fatty acid profile to investigate their involvement in the benthic food-web. Fifteen different saturated and unsaturated fatty acids from bacterial isolates, 14 from actinomycetes and fungal isolates were detected. The total unsaturated fatty acids in bacterial isolates ranged from 11.85 to 37.26%, while the saturated fatty acid ranged between 42.34 and 80.74%. In actinomycetes isolates, total unsaturated fatty acids varied from 27.86 to 38.85% and saturated fatty acids ranged from 35.29 to 51.25%. In fungal isolates unsaturated fatty acids ranged between 44.62 and 65.52% while saturated FA ranged from 20.80 to 46.30%. The higher percentages of unsaturated fatty acids from the microbial isolates are helpful in anticipating the active participation in the benthic food-web of Bay of Bengal.

• Journal of Ecology and Environment
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• v.37 no.4
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• pp.225-229
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• 2014

Feeding behavior of Temora turbinata was investigated through laboratory experiments with special emphasis on its food preference and consequent clearance rate on diatom and microbial components given as common natural food assemblage of coastal area (Uchiumi, Uwa Sea, Japan). Among available prey items, T. turbinata showed the highest clearance rate for Thalassiosira spp. ($0.23{\pm}0.08L\;Temora^{-1}day^{-1}$) followed by Chaetoceros spp. ($0.11{\pm}0.03L\;Temora^{-1}day^{-1}$), but clearance rates for other diatom, Nitzschia spp. was lower (0.03 to $0.07L\;Temora^{-1}day^{-1}$). Bacterial abundances showed no response against 24-h feeding of T. turbinata. Feeding of T. turbinata on heterotrophic nanoflagellates (HNF) was apparent when clearance rates of T. turbinata on diatoms were relatively low, but T. turbinata did not consume HNF as well as ciliates with Thalassiosira spp. of which clearance rate was highest. The results suggest that HNF and ciliates are possible supplementary prey item for T. turbinata, but their contribution as food sources can be limited by the presence of other prey items such as preferable diatom species.

• Journal of Nutrition and Health
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• v.57 no.1
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• pp.75-87
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• 2024

Purpose: Dietary habits are strongly related to the symptoms of people with irritable bowel syndrome (IBS). Therefore, personalized nutrition management can help reduce symptoms and improve the quality of life of people with IBS. This study assessed the effectiveness of a personalized web-based nutrition management based on the types of food that trigger IBS symptoms. Methods: Sixty Korean adults with IBS according to Rome IV criteria in their 20s and 30s were enrolled in this study. The data from the final 49 patients who completed a three-month personalized nutrition intervention were analyzed. The general information, anthropometry, dietary intake survey, and gut microbiota were examined pre and post-intervention. The gut microbiota analysis included the relative abundance and the Shannon index. The food intake was recorded for two days for personalized nutrition education, followed by three months of personalized nutrition intervention. Statistical analysis was performed using the Wilcoxon signed-rank test in SPSS 26.0, with the significance set to p < 0.05. Results: The relative abundance of the gut microbiota changed after personalized nutrition management, with a significant decrease in the presence of Veillonella (p = 0.048). Furthermore, when the gut microbiota was analyzed according to the type of food that triggers symptoms, the diversity was increased significantly in the high fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) type (p = 0.031) and FODMAPs-containing gluten-type personalized nutrition intervention types (p < 0.001). Conclusions: Gut microbial diversity and gut microbiota distribution changed after using web-based personalized nutrition management. Hence, personalized nutrition management that considers trigger foods may improve IBS symptoms.

• Korean Journal of Environmental Biology
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• v.41 no.1
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• pp.89-100
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• 2023

We investigated the spatial distribution of heterotrophic bacteria associated with different water masses in the northern East China Sea(ECS) in summer. The surface water masses were divided into the Changjiang Diluted Water (CDW) and high salinity water (HSW). In the CDW region, the concentrations of dissolved inorganic nitrogen (DIN) and chlorophyll-a (Chl-a), and micro Chl-a contribution were high; and bacterial abundance (BA) and ciliate abundance (CA) were also high. In the HSW region with relatively low DIN concentrations, Chl-a concentration and micro Chl-a contribution were low, but pico Chl-a contribution was increased compared to those in the CDW region. BA did not show any significant difference from the CDW region, but CA was decreased. BA showed a positive correlation with Chl-a concentration in the CDW region; however, it did not show a significant correlation with Chl-a concentration in the HSW region. The ratio of bacterial carbon biomass/phytoplankton carbon biomass was exponentially increased with a decrease in the Chl-a concentration. Compared to the past (1990-2000s), the surface phosphate concentrations and the size of dominant phytoplankton have recently decreased in the ECS. Considering this trend of nutrient decrease and miniaturization of the phytoplankton, our results indicate that changes in the strength of the oligotrophic water mass could alter the function of the microbial food web.

• 한국해양학회지
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• v.27 no.2
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• pp.137-144
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• 1992

Picoplankton in the size range of $0.2-2.0{\;}\mu\textrm{m}$ were enumerated in the Nakdong River estuary on 17 October, 1991 by using an epifluorescence microscope. Numerous minute cells emitting yellow to orange fluorescence at various strengths were recognized and the cells were moistly spherical in shape. Picocyanobacteria seem to comprise most of the picoplankton observed. They also occurred in very polluted water. Cell densities of picoplankton were in the range of $683-3,878{\;}cells{\cdot}ml^{-1}$ at the surface water. In vertical profiles, the Numbers were maximum at subsurface and minimum at surface layer. Percentage picoplankton biomass determined by chlorophyll ranged from undetectable levels to 5.9% of the total chlorophyll. The cell density and chlorophyll a concentrations of picoplankton were relatively low in the study area compared to those of other locations in world ocean, but the study of picoplankton may be important in understanding of microbial food web in the sea.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.6-15
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• 2014

This study was performed to acquire the information on the foodborne pathogen risk management programs in a couple of developed countries by the expert meeting and searching the information on the web. The backgrounds, strategies and effects related to microbial hazards of the foodborne pathogen reduction programs in fresh produce (US), Escherichia coli O157:H7 in ground beef (US), Salmonella in chicken, pork and eggs (Denmark), and Vibrio parahaemolyticus in seafood (Japan) were investigated for case study. A comparison among the pathogen reduction programs was conducted to find advantages and disadvantages and implications of the policies to bring out implications of the programs. A model for foodborne pathogen reduction program was developed based on both the CODEX risk management scheme and the case studies as follows; 1) preliminary risk management activities, 2) planing a foodborne pathogen reduction program, 3) option identification and selection, 4) implementation (conducting the each stake-holders role and applying the intervention methods), 5) monitoring activities, 6) interim review, 7) continuation or amendment of implementation method by the interim review before achieving the goal, and 8) final review and additional cost-benefit analysis if necessary. This proposed model according to the role of the stake-holders can be used to conduct microbial risk management programs in Korea in the near future.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.484-491
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• 2005

Quantitative microbial risk assessment (QMRA) analyzes potential hazard of microorganisms on public health and offers structured approach to assess risks associated with microorganisms in foods. This paper addresses specific risk management questions associated with Staphylococcus aureus in kimbab and improvement and dissemination of QMRA methodology, QMRA model was developed by constructing four nodes from retail to table pathway. Predictive microbial growth model and survey data were combined with probabilistic modeling to simulate levels of S. aureus in kimbab at time of consumption, Due to lack of dose-response models, final level of S. aureus in kimbeb was used as proxy for potential hazard level, based on which possibility of contamination over this level and consumption level of S. aureus through kimbab were estimated as 30.7% and 3.67 log cfu/g, respectively. Regression sensitivity results showed time-temperature during storage at selling was the most significant factor. These results suggested temperature control under $10^{\circ}C$ was critical control point for kimbab production to prevent growth of S. aureus and showed QMRA was useful for evaluation of factors influencing potential risk and could be applied directly to risk management.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.263-271
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• 2004

To collect the basic ecological information about the microbial food webs in eutrophic water system with different residence time, the monthly variation of bacterioplankon (bacteria and small-sized cyanobacteria) and nanoplankton (phytoplankton and protists) were examined from December 2000 to September 2001. Kyungan stream is shorter in resident time (ca.5.4 d) than Seokchon reservoir (ca.72 d), even though they showed the same pattern in precipitation. With the basic environments, we examined the biomass (standing crops and its carbon content) of each plankton collected from the surface water. Large-sized planktons flourished in the time of low temperature, while small planktons were in the time of the high temperature period. Especially, in the Kyungan stream with much disturbance by rainfall and outflow, high diversity showed in term of species and cell morphology, compared to that of Seokchon lake. The time-lag relationship remarkably showed between phytoplankton and bacteria in Seokchon reservoir, and between protists and bacteria in Kyungan stream, respectively.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.379-387
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• 2011

Copepod nauplii plays an important role as a linker between the microbial food web and classical food chain in marine ecosystem and is an essential food source for early stage of many larval fishes. Study on the influencing factors on the growth of copepod naupliar stages has been rarely carried out in despite of these ecological significances. Many studies have shown that food availability and temperature are major factors to influence copepod growth. However, due to the complicated environment parameters in coastal ecosystem, the relationships between growth of copepods and influencing factors are still unclear under the natural condition. Growth rates of the copepod $Acartia$ $hongi$ nauplii were measured in Kyeonggi Bay from February to December 2001. $Acartia$ $hongi$ is numerically abundant and widespread predominant species in the coastal regions of the Yellow Sea and occurs continuously throughout the year, with a maximum peak in late spring. The naupliar growth rates of $Acartia$ $hongi$ by the artificial cohort method varied from 0.03 to 0.18 $day^{-1}$, with a mean of 0.09 $day^{-1}$. The overall naupliar growth rates showed a significantly positive relationship with the variation in water temperature. However, Previous study reported that the growth rates of adult $Acartia$ $hongi$ were primarily influenced by the variation in chlorophyll-$a$. Therefore, these differences demonstrated that the influencing factors of growth did not correspond with the developmental stages. The results of this study suggest that the dissimilarity of growth between nauplius and adult female resulted from the size-dependant difference in food availability and the growth of older developmental stages containing adults are more food-dependent than juveniles.