• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.73-82
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• 1999

To verify the usefulness of enzyme activity as a index for the stability or maturity of apple pomace composting. the succession of microbial populations using viable count procedure. and Vmax of ${\beta}$-glucosidase and cellobiohydrolase were measured. based on an increase in fluorescence as the nonfluorescent methylumbelliferyl substrates were enzymatically hydrolyzed, leading to the highly fluorescent methylumbelliferyl molecule 4-methylumbelliferone(MUF). The activities of these enzymes in the decomposition of carbohydrates were gradually decreased in the course of the time. Correlation between microbial population and enzyme activity was not significant with exception of fungi. and the fungi were represented in high density. This indicates that the fungi probably play a major role in composting of apple pomace.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.116-123
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• 2018

The objective of this study was to examine effects of stand age on soil $CO_2$ efflux in plantation Pinus koraiensis, and to elucidate what extent plant (fine) root and soil microbial biomass contribute to the whole soil $CO_2$ efflux. In three age classes (20-yr-old. 40-yr-old, 70-yr-old) of plantation Pinus koraiensis, in-situ soil respiration, plant fine root biomass and soil microbial biomass were measured from April to November in 2004. Regardless of stand age, soil temperature and soil $CO_2$ efflux increased until July then slowly decreased. Soil respiration was higher in 70-yr-old stand than in 20- and 40-yr stands. Fine root biomass and soil microbial biomass was also higher in 70-yr-old stand. Root exclusion decreased soil respiration in 40-yr stand, but not in 70-yr stand. Soil microbial biomass was higher in 70-yr stand, but there was no monthly variation between July and November. The results suggest that soil respiration may increase as plant stand ages and microbial contribution could play more roles in older stands.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.319-325
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• 1999

A culture-dependent survey of bacterial community in the soil-root system of red pepper and tomato was conducted by dilution plate count method. The bacterial community within soil was not different from that of rhizoplane. However, the populations of fluorescent, pseudomonads were higher in rhizoplanes than in soils and higher in healthy rhizoplanes than in Phytophthora disease-infested rhizoplanes. The bacterial community of the pepper cropped soil and rhizoplanes was very similar to that of the tomato-cropped soil and rhizoplanes. Among 285 identified bacterial colonies, most colonies were belong to two groups by fatty acid analyses: 52% of the 285 colonies were belong to low G + C gram positive bacteria group. Bacillus spp. and 33% were belong to high G + C gram positive bacteria group. In order to use beneficial microorganisms to agro-ecosystem, these data of field trials should be intensively accumulated.

• Korean Journal of Microbiology
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• v.34 no.4
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• pp.188-193
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• 1998

The authors examined the variations of environmental factors, the distributions of cyanobacteria, heterotrophic bacteria, and microorganisms that inhibit the growth of Anabaena cylindrica according to development and extinction of cyanobacterial bloom at a site in Daechung Dam reservoir. And certified the relationship between each other. Water temperature variated in a typical pattern. pH and concentrations of dissolved oxygen and chlorophylla was high in bloom period, and lowered with the decline of bloom. Phosphorus played as a growth-limiting factor at this study site. Total nitrogen concentration increased during blooming period, which indicated that nitrogen has been fixed by aquatic organisms such as cyanobacteria. Cyanobacteria distributed from June 17, and such cyanobacterial species as Anabaena spp., Aphanizomenon spp., Microcystis spp., Oscillatoria spp. and Phormidium spp. was detected during study period. Anabaena spp. distributed relatively highly distributed from July 23 to September 22, and disappeared completely at September 29. Heterotrophic bacterial and cyanobacterial populations varied inverse-proportionally. There was a relevancy between the variations of Anabaena spp., heterotrophic bacteria, and microorganisms that inhibit the growth of Anabaena cylindrica. Microorganisms that inhibit the growth of Anabaena cylindrica distributed from early growth phase of Anabaena spp. population to immediately after the extinction of Anabaena spp. With the population of Anabaena cylindrica growth-inhibiting microorganisms decreasing, increases of heterotrophic bacterial population followed it. Thease results indicate that microorganisms have a part in the extinction of cyanobacterial bloom, especially at its destroying period.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.398-404
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• 2022

Bis(2-ethylhexyl) phthalate (DEHP) is one of the plasticizers used in the polyvinyl chloride(PVC) industry. It is known to be easily released into the environment. In this study, we investigated effects of DEHP on growth, metabolic pathway, and virulence gene expression in soil-borne bacterial plant pathogen, Pectobacterium carotovorum SCC1 using in vitro assays. As a result, DEHP at 20 ㎍ mL^-1 did not affect the growth, cell membrane permeability, or ATPase activity of P. carotovorum SCC1. However, it decreased succinyl-CoA synthase (SCS) activity in the tricarboxylic acid (TCA) cycle. Relative expression levels of virulence genes encoding pectate lyase and pectin were differentially influenced by DEHP treatment. These results suggest that biological characteristics of P. carotovorum might be influenced by DEHP in soil.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.79-85
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• 2002

Ecological characteristics of microorganisms in tideland soils were studied by investigation of microbial diversity and population. Twenty soil samples were taken at surface, 10, 20 and 30 cm depth each. Bacteria, actinomycetes and fungi were isolated on each selective isolation medium containing different concentration of NaCl. Actinomycetes were the most isolated from soil samples taken at 10 cm depth and isolated by humic acid-vitamin (HV) medium without sea water or salt. Twenty nine strains of actinomycetes were isolated at surface soil and 74, 39, 37 strains were at 10, 20, and 30 cm depth, respectively. All these isolates were analysed and grouped by random amplified polymorphic DNA (RAPD)-PCR analysis. Many of the isolates were clustered into Microtetraspora and Pseudonocardia. Fungal isolates were highly distributed at the surface soil and isolated well on potato dextrose agar (PDA) medium with sea water. Bacterial isolates were higly distributed at surface soil and isolated well by nutrient medium without sea water or salt. Soil samples taken at 10 cm depth showed the highest microbial diversity and population.

• Korean Journal of Microbiology
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• v.37 no.1
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• pp.1-8
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• 2001

Spiders are carnivores that prey upon insects and other small arthropods through digestion of food outside the body. Although spider poison may contain proteolytic enzymes, these are thought to play an insignificant role in actual digestion. The source of active proteolytic enzymes can be either the digestive tract cells of spider, or natural microbial flora in the digestive tract of spider. In this study, digestive tracts from the spider, Nephila clavata, were screened for bacteria that have protease or lipase activity. A total of $10^3-10^5$ CFU was recovered from a spider and more than 90% of them showed protease and lipase activity respectively. Of the microbial isolates, 63.3% showed protease or lipase activity, and 50% of these showed both protease and lipase activity. Some of the isolates were characterized using a battery of chemical, phenotypic and genotypic methods. Eleven Gram negative bacteriaa (Acinetobacter calcoaceticus, A. haemolyticus, Alcaligenes faecalis, Cedecea davisae, C. neteri, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas fluorescens, Serratia marcescens, Stenotrophomonas maltophilia, Suttonella indologenes) and 11 Gram positive bacteria (Bacillus cereus, B. coagulans, B. pasteurii, B. thuringiensis, Cellulomonas flavigena, Corynebacterium martruchotii, Enterococcus durans, E. faecalis, Micrococcus luteus, Staphylococcus hominis, S. sciuri) were identified.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.244-248
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• 1987

Attempts were made to enumerate the number of Gram positive and negative bacteria in the development of natural fermentation rapidly and simultaneously. A general Gram stain was applied to this study. The number of cells by Gram stain was proportional to the cell turbidity by spectrophotometer within a range of 0.7 absorbance at 610nm. The cells washed out during procedures were not exceeded about 8 percentage. The standard error of separate counts in the mixture of Cscherichia coli and Micrococcus luteus was $5.1\pm2.3$%. The possible range of counting was $5.5\times 10^{7}-1.0\times 10^{9}$ cells/ml. Therefore, it is believed that a general Gram stain could be applied to the separate counting of mixture of Fram positive and negative bacterial populations too. In practice, growth kinetics of hemp retting and Kimchi fermentation were presented.

• Korean Journal of Environmental Biology
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• v.28 no.3
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• pp.172-178
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• 2010

The bloom of the genus Stephanodiscus was gradually extinguished after 18 April. Counts of bacterial population were increased as the diatom bloom was disappeared. Numbers of the heterotrophic nanoflagellates and ciliates were also increased during the disappearance of the bloom. The densities of the mesozooplankton, the major predator of the diatoms, started to increase in April. However, their growth was suppressed during the bloom period of the diatoms (from January to March). During the bloom period of the diatoms, the monthly average value of the basic productivity amounted up to 11,765.7 mgC $m^{-2}day^{-1}$, which is relatively high value considering the low temperature and light during that period. The growth rate of phytoplankton in March, when the bloom was beginning to be supressed was 0.007. The growth rate of phytoplankton was negative value in April when the decreasing of the algal density was started.

• Journal of Food Hygiene and Safety
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• v.32 no.1
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• pp.8-13
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• 2017

This study was conducted to develop an agent-based computing platform enabling simulation of on-farm produce contamination by enteric foodborne pathogens, which is herein called PPMCS (Preharvest Produce Microbial Contamination Simulator). Also, fecal contamination of preharvest produce was simulated using PPMCS. Although Agent-based Modeling and Simulation, the tool applied in this study, is rather popular in where socio-economical human behaviors or ecological fate of animals in their niche are to be predicted, the incidence of on-farm produce contamination which are thought to be sporadic has never been simulated using this tool. The agents in PPMCS including crop, animal as a source of fecal contamination, and fly as a vector spreading the fecal contamination are given their intrinsic behaviors that are set to be executed at certain probability. Once all these agents are on-set following the intrinsic behavioral rules, consequences as the sum of all the behaviors in the system can be monitored real-time. When fecal contamination of preharvest produce was simulated in PPMCS as numbers of animals, flies, and initially contaminated plants change, the number of animals intruding cropping area affected most on the number of contaminated plants at harvest. For further application, the behaviors and variables of the agents are adjustable depending on user's own scenario of interest. This feature allows PPMCS to be utilized in where different simulating conditions are tested.