• Korean Journal of Food Science and Technology
• /
• v.22 no.1
• /
• pp.26-32
• /
• 1990

Attempts were made to define the characteristics of microbial community as an indicator of Kimchi fermentation. Determination of communities was carried out by simple Gram-stain, followed by direct microcopic counts. In room-temperature $(15^{\circ}C)$ fermentation, microbial succession was occurred in the order of communities of Gram-positive bacteria, yeasts and Gram-negative bacteria. It was characteristic that Gram-positive bacterial community was developed during the production of lactic acid, yeasts community was developed to cause rancidity, and Gram-negative bacterial community was relevant to maceration (or softening) as well as rancidity. The fluctuation of apparent Gram-negative reaction group might be used as a criterion of death or aging of Gram-positive bacterial populations. In low-temperature fermentation $(5^{\circ}C)$, however, it was found that yeasts and Gram-negative bacterial communities did not developed but only Gram-positive bacterial community did. It follows from these results mentioned above that maturity of Kimchi depends on the development of Cram-positive bacterial community. Thus, the size and occurrence of microbial community are avaiable for an indicator of Kimchi fermentation, and also determination of community could be a useful method to predict the maturity.

• Horticultural Science & Technology
• /
• v.30 no.3
• /
• pp.261-269
• /
• 2012

Soil microbial community and soil physiological parameters were investigated by analyzing phospholipid fatty acids extracted from the soils amended with chitosan powder and solution in a cucumber greenhouse. The soils were sampled at 90, 160, 200 days after treatment. Identified fatty acids were analyzed with principal component (PC) analysis. Chitosan powder soils and chitosan solution soils were separated from non-treated control soils by PC1 and PC2 90 days after treatment, respectively. And chitosan powder soils were separated from non-treated control soils by PC2 160 days after treatment. The ratio of fungi to bacteria increased significantly in chitosan solution-amended soils compared with the control soils 90 days after treatment. Microbial groups and physiological parameters were investigated 160 days after treatment: vesicular-arbuscular mycorrhizal fungi (VAM) significantly increased in soils amended with chitosan powder compared with other soils, the ratio of gram negative bacteria to gram positive bacteria and cyclo-fatty acids to precursors were significantly higher and lower in soils amended with chitosan solution and chitosan powder compared with control soils, respectively, and the ratio of fungi to bacteria were significantly lower in control soils compared with chitosan-treated soils. The chitosan powder increased the ratio of aerobic to anaerobic bacteria and lowered the ratio of saturated to unsaturated fatty acids compared with chitosan solution 200 days after soil application. In conclusion, chitosan powder changed the soil microbial community and the effects maintained up to 160 days after soil application. The effect of physiological parameters on the soil microbial community started to appear 160 days after and continued up to 200 days after soil application of chitosan.

• Food Science and Preservation
• /
• v.24 no.1
• /
• pp.36-43
• /
• 2017

The aim of this study was to provide the quality index of salted Korean cabbage in a short-term distribution system. Salted Korean cabbages were packaged with or without 2% salt water, and then distributed in a conventional system (CVS) and a cold-chain system (CCS) for 6 h. The material temperature of samples with and without salt water gradually increased to $19.57^{\circ}C$ and $19.43^{\circ}C$ in a CVS, respectively and to $10.73^{\circ}C$ and $12.90^{\circ}C$ in a CCS, respectively. Salinity of the materials in a CCS did not change, whereas salinities of the materials in a CVS were 1.2 and 1.7 fold higher, respectively. Also, a slight increase in acidity was observed in both packaging materials in a CCS. In the case of a CVS, total aerobic bacteria and lactic acid bacteria increased to 7.62 log CFU/g and 6.77 log CFU/g in the materials with salt water, respectively, whereas the number of total aerobic bacteria and lactic acid bacteria ranged between 5.62-5.85 log CFU/g and 4.33-4.83 log CFU/g in the materials without salt water, respectively. However, significant microbial changes were not observed in a CCS as distribution time increased. CCS with salt water packaging was effective in achieving microbial control and maintaining physicochemical quality. Salinity, aerobic bacteria, and lactic acid bacteria can be useful as quality indices for a CVS, and acidity can be useful as quality index for a CCS.

• Journal of Korean Society of Water and Wastewater
• /
• v.20 no.4
• /
• pp.627-635
• /
• 2006

Combined sewer overflow (CSOs) is a primary diffuse source degrading water quality of urban streams. In this study, CSOs caused by 5 different rainfall events at an urban watershed located in Daejeon city were monitored for the indicator microorganism concentrations. Event mean concentration (EMC) of the indicator microorganisms were: total coliform = $2.46{\times}10^6CFU/100mL$; fecal coliform = $1.01{\times}10^6CFU/100mL$; E.coli = $5.20{\times}10^5CFU/100mL$; and Fecal Streptococci = $6.08{\times}10^5CFU/100mL$. In addition, coliform concentrations were well correlated with suspended solid concentrations and the first flush effects were identified. Settling tests were carried out to estimate removal rate of indicator organisms by sedimentation from CSOs. As microorganisms are discharged in association with suspended solid, ten minutes of settlement can lower 44% of indicator microorganism leading.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2004.05a
• /
• pp.36-36
• /
• 2004

• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.527-532
• /
• 1997

The comparative effects of gamma irradiation and ozone treatment on the microbial inactivation and fatty acid composition were investigated for improving hygienic quality of aloe and pollen powders. Gamma irradiation at 10 kGy resulted in sterilizing total aerobic bacteria, molds and coliforms below detective levels, while ozone treatment for 8 hours up to 18 ppm did not sufficiently eliminate the microorganisms of aloe and pollen powders. The compositions of fatty acid were not significantly changed by gamma irradiation up to 10 kGy. However, ozone treatment markedly decreased unsaturated fatty acids by approximately $20{\sim}80%$ in contents, whereas it significantly increased saturated fatty acids (p<0.05).

• Korean Journal of Microbiology
• /
• v.34 no.3
• /
• pp.120-125
• /
• 1998

A plasmid pNPG contains a genomic DNA complementing npgA1 which is located on the left arm of linkage group I. It transformed Aspergillus nidulans at a high frequency. No abortive transformants were observed and the $Trp^+$ transformants were all $Npg^+$. The 10.4 kb Psti fragment of the genomic DNA was subcloned into pILJ16, which increased the transformation efficiency by more than 200-folds. The transformants were mitotically unstable and yielded $Arg^-$ conidia at the frequency of more than 80%. An additional gene cloned into the plasmid containing the fragment was always lost with $argB^+$ marker. These characteristics strongly indicate the possibility that the plasmids autonomously replicate. The full activity of enhanced transformation was retained on the 4.9 kb EcoRI-HaeIII fragment. The DNA segment was similar to AMA1 rather than ANS1 in function and designated AMA2.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.4
• /
• pp.385-392
• /
• 2008

In this study, seawater intrusion was assessed employing a kind of biological parameters such as Escherichia coli and Enterococcus faecalis while lab-prepared reclaimed water was recharged to prevent seawater intrusion. Chemical factors indicating seawater intrusion such as Cl$^-$, Ca$^{2+}$, Mg$^{2+}$ and specific conductivity were also simultaneously investigated where an ion exchange between a matrix in artificial aquifer and cations in solution was estimated. Both Escherichia coli and Enterococcus faecalis were shown to be very sensitive against degree of salinity during saline water intrusion. Enterococcus faecalis more strongly resisted against salinity than that of Escherichia coli. The ratio of Enterococcus faecalis divided by E. coli in the process of seawater intrusion increased up to more than 50$\sim$100 times in 18 hours whereas E. coli was died off more than 90% during pumping and recharge rate kept at 10 mL/min. However, when the rates of both recharge and pumping was kept at 5 mL/min, Enterococcus faecalis / Escherichia coli was sustained in the range of 2.5$\sim$5.0, while Escherichia coli showed dimished death rate. Chemical factors such as Cl$^-$, Ca$^{2+}$, Mg$^{2+}$ and specific conductivity showed more than 0.9 of high correlation each other well explaining the degree of seawater intrusion. The degree of ion exchange between artificial aquifer and saline water can be efficiently interpreted by both minus $\Delta$Na, $\Delta$Mg variation and positive $\Delta$Ca variation.

• Korean journal of food and cookery science
• /
• v.21 no.4 s.88
• /
• pp.440-446
• /
• 2005

To determine the shelf-life of low salted Myungran-jeot (low salted and fermented Alaska pollack roe), various chemical, microbiological and sensory analyses were carried out with Myungran-jeot stored at 10 days. The lactic acid content was slowly increased in the early stage of storage but then was rapidly increased with lengthening storage period, while pH was decreased during storage. The $NH_2-N$ content was steady at 10 days and peaked at 17 days. The production of VBN was increased to over $30mg\%$ at 19 days. In microbiological tests, the viable cell count and halotolerant bacteria were $1.5\times10^3\;and\;5.5\times10^3CFU/g$, respectively, at the initial state, but they slowly increased to $10^7 CFU/g$ at 17 days. Yeast or fungi did not appear on the surface of Myungran-jeot. Sensory evaluation showed that the original torture of Myungran-jeot in the mouth was a very important indicator for acceptability. Sensory characters and acceptability of Myungran-jeot at 17 days were not significantly different from those of the initial state. From these results, the estimated shelf-life of Myungran-jeot whom sealed with aluminum coated paper, was about 18 days in this study.

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