• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.359-369
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• 2007

Amoebophrya is an obligate endoparasitic eukaryotic dinoflagellate infecting host species and eventually killing them within a short period. Because of its host specificity and significant impacts on population dynamics of host species, it has long been proposed to be a potential biological agent for controlling harmful algal bloom (HAB). For several decades, the difficulties of culturing host - parasite systems have been a great obstacle to further research on the biology of Amoebophrya but recent success of several culture systems reactivates this research field. In this study, as a preliminary work for understanding the impacts of Amoebophrya on the population dynamics of host species, semimonthly occurrence of infected host dinoflagellates by Amoebophrya spp. had been observed in Jinhae Bay for two years and with a host - parasite system cultivated, host specificity of Amoebophrya spp. on several dinoflagellates was tested. Amoebophrya spp. were observed in the cellular organelle and cytoplasm of several species including Akashiwo sanguinea, Ceratium fusus, Dinophysis acuminata, Heterocapsa triquetra, Oblea sp., Prorocentrum minimum, P. triestinum, Scrippsiella spinifera, and S. trochoidea. Among them two host - parasite systems for an athecate dinoflagellate, A. sanguinea, and for a thecate dinoflagellate, H. triquetra, had been able to be successfully established as laboratary cultures. Cross-infection tests for 6 species of dinoflagellates in which Amoebophrya was observed or had been reported to exist confirmed high preference for host species of the parasite. Through the continuous research on Amoebophrya occurring in Korean coastal waters, we need to maintain various host - parasite culture systems, which will be very helpful for understanding its ecological role in marine food webs and for applying the species to biologically control harmful algal blooms.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.3
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• pp.160-167
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• 2007

Shelf-stability of powdered model food was determined during storage at various temperatures ($25^{\circ}C$, $35^{\circ}C$) and various moisture contents (3.5%, 6.0%, 8.0%). Moisture content, peroxide value, pH, color, microbial counting and sensory evaluation were conducted during storage. Moisture content, peroxide value, pH and color were not significantly changed during storage in all samples indicating that this powdered model food was relatively stable at given conditions. Pathogenic microorganisms, such as Bacillus cereus, Listeria spp., Clostridium perfrigens, Salmonella spp. and Staphylococcus aureus, were not found during storage suggesting that there was no problem in safety in this case. On the other hand, the number of artificially added Lactic acid bacteria was decreased with increasing both storage temperature and moisture content. Therefore, powdered model food was very shelf-stable and it was impossible to predict the shelf-life using above quality factors.

• The Korean Journal of Mycology
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• v.46 no.3
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• pp.271-280
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• 2018

The ectomycorrhizal basidiomycete Tricholoma is one of mushroom groups that cannot be cultivated artificially. To use this mushroom as applicable resource for food production, it is necessary to obtain information about their mycelial growth properties in various environmental conditions. This study investigated the mycelial growth of four domestic isolates of Tricholoma species (T. bakamatsutake, T. fulvocastaneum, T. matsutake, T. terreum) at different physical and chemical conditions. The optimal physical conditions for their mycelia growth were found to be a temperature range of $20{\sim}25^{\circ}C$ and a pH range of 4.0~7.0 in dark condition. The growth of T. matsutake was retarded at high temperature ($30^{\circ}C$). Tests to determine the chemical factors that affected mycelial growth showed that the four Tricholoma spp. grew 1% saline. T. matsutake grew in up to 2% saline. In the presence of various heavy metals (50 ppm) and pesticides (suppliers' recommended concentration), mycelial growth was inhibited the most by cadmium and emamectin benzoate, respectively. However, all the four Tricholoma spp. grew with $Cu^+$. The growth of T. matsutake was not inhibited by abamectin, acetamiprid, and thiacloprid. Extracellular enzyme activities of amylase and ${\beta}$-glucosidase were detected only in T. bakamatsutake and T. fulvocastaneum. The results of the present study allowed us to determine suitable or harmful environmental conditions for the mycelial cultivation of the Tricholoma spp.

• Parasites, Hosts and Diseases
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• v.55 no.5
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• pp.523-532
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• 2017

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor.

• Journal of Mushroom
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• v.16 no.1
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• pp.45-50
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• 2018

This study was performed to compare medium characteristics during the composting stage for medium turning performed using an excavator agitator and a prototype medium turner in button mushroom cultivation. The changes in temperature in the medium did not significantly differ between the treatments until the 3rd turn performed using the excavator agitator. However, during the 4th and 5th turns, the temperature increased during turning with the prototype medium turner. During outdoor composting, various types of microorganisms such as thermophilic bacteria (Bacillus spp.), Actinomycetes, fluorescent Pseudomonas spp., and filamentous fungi were found to be distributed in the medium. The counts of aerobic bacteria and fluorescent Pseudomonas spp. did not significantly differ between treatments, and the counts of thermophilic bacteria and thermophilic actinomycetes were slightly higher during turning with the prototype medium turner. The rice straw was slightly shorter and water content lower for the prototype medium turner. There was no significant difference between pH and EC treatments. The L, a, and b values tended to increase on turning with the prototype medium turner.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.506-510
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• 2013

This study aimed to understand relationship between potential risky species and environmental factors at ports in Korea. During the study periods, 25 potential risky species (red tide and toxic species) representing 20 red-tide species, 5 toxic species were observed in the all ports. Skeletonema costatum (red-tide species) was predominated in all study area. This species showed positive correlation with pH, while negative correlation with dissolved oxygen (p<0.05) at Busan port. Also, this species showed positive correlation with total suspended solids and pH (p<0.05) at Ulsan port. However, Sk. costatum showed positive correlation with nitrate at Incheon port (p<0.01). Pseudo-nitzschia spp. producing amnesic shellfish poison (domoic acid) showed positive correlation with nitrate and silicate in all study areas (p<0.05). Alexandrium spp. (paralytic shellfish poison) and Dinophysis acuminata (diarrhetic shellfish poison) were affected by chemical oxygen demand (p<0.01). Our results indicated that red-tide species were affected by physical factors, while chemical factors affected toxic species.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.585-599
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• 2009

This study was carried out to investigate the antifungal activity of the water soluble essential oil against Trichoderma spp. Water soluble essential oils from Pinus densiflora and Chamaecyparis obtusa were obtained from GAP (Gas assisted process) extraction apparatus. When the water soluble essential oil was treated, the growth of the conidial germination was maximum under the cultivation condition at $25^{\circ}C$ and in the culture medium adjusted to pH 5.0. The yield of water soluble essential oil was 3.9% and 3.7% in P. densiflora and C. obtusa, respectively. 24 and 15 kinds of compounds were identified in water soluble essential oils of P. densiflora and C. obtusa, respectively. The major components in the essential oil of P. densiflora were $\alpha$-Terpineol acetate and Terpinen-4-ol and those of C. obtusa were Terpinen-4-ol and $\alpha$-Terpineol. Antifungal activity was the best in the 5000 ppm of P. densiflora against Trichoderma harzianum and in 5000 ppm of C. obtusa against Trichoderma atroviride.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.720-734
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• 2023

To understand the spatiotemporal distribution pattern of zooplankton and the environmental factors influencing zooplankton abundance in Gomso Bay, major harvesting area of Manila clam (Venerupis philippinarum) in South Korea, zooplankton sampling was conducted four times in autumn (October 2022), winter (January 2023), early spring (March 2023), and spring (May 2023). Among the environmental factors of Gomso Bay, water temperature, chlorophyll a concentration (Chl-a), dissolved oxygen (DO), and pH observed different patterns, while salinity and suspended particulate matter(SPM) showed no significant statistical differences between the survey periods. The zooplankton in Gomso Bay occurred 33, 29, 27, and 29 taxonomic groups during each respective survey period. In October 2022 and May 2023, arthropod plankton were dominated, while in January and March 2023, protozoa were primarily dominant. Among the Arthropods, copepods including Acartia hongi, Paracalanus parvus s. l., Corycaeus spp., and Oithona spp. commonly found along Korean coastal areas of the Yellow Sea, were dominated. Cluster analysis based on zooplankton abundance indicated a single community (stable condition) in each season, attributed to low dissimilarity distances, while three distinct clusters (autumn, winter-early spring, spring) between seasons indicated a highly seasonal environment in Gomso Bay.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.437-442
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• 1996

Two strains of Lactobacillus(L.) casfi and one strain of L. Pentosus, which were isolated from pickles, were used to investigate in studing their characteristics of ${\beta}-galactosidase$. The preferable carbon sources and pH of the MRS media for enzyme production from L. casei No.10 was found to be 1.0% lactose and pH 7.5, from L. Pentosus No.63 was 1.0% galactose and pH 7.5, and from L. casei No.36 was 1.0% lactose and pH 6.5, respectively. The maximum enzyme production from each strain was found after 48 hours culture at $30^{\circ}C$ in a medium with preferable carbon source. The optimum reaction temperature with substrate for ${\beta}-galactosidase$ activity was found at $60^{\circ}C$ for all three strains . The stability of enzyme from L. casei No.36 was found to be at $45^{\circ}C$, from L. Pentosus No.63 was found at $55^{\circ}C$. This stability from L. casei No.36 was found at $40^{\circ}C$, but it was reduced to 60% at $55^{\circ}C$. These stabilities of enzymes remained about 90% at $40^{\circ}C$ for all three strains. The optimal pH for enzyme activities was found to be pH 6.5 for all three strains. Enzyme activity remained over 90% for L. casei No.10 at $pH\;5.0{\sim}6.0$, for L. casei No.36 at $pH\;5.0{\sim}8.0$, and for L. pentosus No.63 at $pH\;6.0{\sim}7.0$.

• Microbiology and Biotechnology Letters
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• v.34 no.4
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• pp.311-317
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• 2006

Using PCR amplification, we cloned a cellulase gene (ce/H) from the Bacillus subtilis AH18 which has plant growth-promoting activity and antagonistic ability against pepper blight caused by Phytophthora capsici. The 1.6 kb PCR fragment contained the full sequence of the cellulase gene and the 1,582 bp gene deduced a 508 amino acid sequence. Similarity search in protein database revealed that the cellulase of B. subtilis AH18 was more than 98% homologous in the amino acid sequence to those of several major Bacillus spp. The ce/H was expressed in E. coli under an IPTG inducible lac promoter on the vector, had apparent molecular weight of about 55 kDa upon CMC-SDS-PAGE analysis. Partially purified cellulase had not only cellulolytic activity toward carboxymethyl-cellulose (CMC) but also insoluble cellulose, such as Avicel and filter paper (Whatman No. 1). In addition, the cellulase could degrade a fungal cell wall of Phytophthora capsici. The optimum pH and temperature of the ce/H coded cellulase were determined to be pH 5.0 and $50^{\circ}C$. The enzyme activity was activated by $AgNO_3$ or $CoCl_2$. However its activity was Inhibited by $HgC1_2$. The enzyme activity was activated by hydroxy urea or sodium azide and inhibited by CDTA or EDTA. The results indicate that the cellulase gene, ce/H is an antifungal mechanism of B. subtilis AH18 against phytophthora blight disease in red-pepper.