• Korean Journal of Microbiology
• /
• v.52 no.3
• /
• pp.365-374
• /
• 2016

In high-latitude regions, temperature has risen ($0.6^{\circ}C$ per decade) and this leads to the increase in microbial degradability against soil organic carbon (SOC). Furthermore, the decomposed SOC is converted into green-house gases ($CO_2$ and $CH_4$) and their release could further increase the rate of climate change. Thus, understanding the microbial diversity and their functions linked with SOC degradation in soil-thawing model is necessary. In this study, we divided tundra soil from Council, Alaska into two depth regions (30-40 cm and 50-60 cm of depth, designated as SPF and PF, respectively) and incubated that for 108 days at $0^{\circ}C$. A total of 111,804 reads were obtained through a pyrosequencing-based metagenomic study during the microcosm experiments, and 574-1,128 of bacterial operational taxonomic units (OTUs) and 30-57 of archaeal OTUs were observed. Taxonomic analysis showed that the distribution of bacterial taxa was significantly different between two samples. In detail, the relative abundance of phyla Actinobacteria and Firmicutes largely increased in SPF and PF soil, respectively, while phyla Crenarchaeota was increased in both soil samples. Weight measurement and gel permeation chromatography of the SOC extracts demonstrated that polymerization of humic acids, main component of SOC, occurred during the microcosm experiments. Taken together our results indicate that these bacterial and archaeal phyla could play a key function in SOC degradation and utilization in cold tundra soil.

• Journal of Food Hygiene and Safety
• /
• v.35 no.6
• /
• pp.535-543
• /
• 2020

In addition to the ubiquitous roles of cellular RNA in genetic regulations, gene expression and phenotypic variations in response to environmental cues and chemotactic signals, the regulatory roles of a new type of RNA called extracellular RNAs (exRNAs) are an up-and-coming area of research interest. exRNA is transported outside the cell through membrane blebs known as membrane vesicles or extracellular vesicles (EVs). EV formation is predominant and conserved among all microbial forms, including prokaryotes, eukaryotes, and archaea. This review will focus on the three major topics concerning bacterially derived exRNAs, i.e., 1) the discovery of exRNA and influence of extraneous RNA over bacterial gene regulations, 2) the known secretion mechanism for the release of exRNA, and 3) the possible applications that can be devised with these exRNA secreted by different gram-negative and gram-positive bacteria. Further, this review will also provide an opinion on exRNA- and EV-derived applications such as the species-specific exRNA markers for diagnostics and the possible roles of exRNA in probiotics and the epigenetic regulations of the gut microbiome.

• Journal of Sericultural and Entomological Science
• /
• v.51 no.1
• /
• pp.9-14
• /
• 2013

Although the mealworm larva (Tenebrio molitor) is high protein source, aversion feature of the larva made it difficult for consuming as a food. In this study, we established optimal powder manufacturing process for T. molitor larva for using as a novel food. For this purpose, it should be feed with the bran sterilized by water vapor for 3-5 days, starved without water or food for 3 days, and then the larvae were sterilized before freeze-drying. The sterilized T. molitor was lyophilzed and grinded by a blender. A safety of the powder as a food was validated by evaluation of Raw 264.7 macrophage cytotoxicity using MTS assay. As above results, we propose that optimal powder manufacturing process established in this study can be used in industrial production of T. molitor as a novel food.

• Research in Plant Disease
• /
• v.10 no.3
• /
• pp.167-174
• /
• 2004

To make the forecasting model of rice bacterial grain rot (RGBR) using the statistical procedures with SAS(Statistical Analysis System) based on micro-weather factors during heading period of rice, 21 rice varieties having the different heading time (40％ panicles headed) were planted at 30 May and 15 June in Naju. Heading time and diseased panicles were investigated from July to August in 1998. RGBR mainly occurred on varieties headed from 29 July to 19 August, but not on varieties headed after 22 August. RGBR was highly correlated with diurnal temperature during 7 days (r =-0.871 **) and 10 days (r =-0.867**) and minimum relative humidity during 15 days from 3 days before heading time. After examining the models with several ways ($R^2$, Adjusted $R^2$, MSE), one equations were selected： Y =92.83 - 2.43Tavr + 1.88Tmin - 1.04RHavr + 0.37RHmin + 0.43RD - 3.68WS ($R^2$=0.824) using six variables of average and minimum temperature (Tavr and Tmin), average and minimum relative humidity (RHavr and RHmin), rainy days (RD), and wind speed (WS) during 7 days from 3 days before to 3 days after heading time.

• Korean Journal of Food Science and Technology
• /
• v.48 no.4
• /
• pp.301-305
• /
• 2016

This study was conducted to investigate changes in pH, volatile basic nitrogen (VBN), thiobarbituric acid (TBA), $a^*$ (redness), shearing force, and microbial content (total plate count; TPC) in beef during freezing storage at -1, -5, and $-20^{\circ}C$ for 21 days. TPC as an effective quality indicator was used to identify the decay point by regression analysis. The pH, TBA values, and TPC significantly increased with storage at all tested temperatures (p<0.05). VBN significantly increased and shearing force significantly decreased with storage at -1 and $-5^{\circ}C$ (p<0.05). TPC showed significant correlation with temperature at $-1^{\circ}C\;(R^2=0.891)$, $-5^{\circ}C\;(R^2=0.856)$, and $-20^{\circ}C\;(R^2=0.444)$. The decay points at -1, -5, and $-20^{\circ}C$, were 27, 52, and 84 days, respectively. The results suggest that a freezing temperature of $-5^{\circ}C$ is effective for short-term storage of beef.

• Journal of Life Science
• /
• v.19 no.3
• /
• pp.411-416
• /
• 2009

Chitosan is derived from chitin by a process of controlled deacetylation. In the present study, we investigated the effects of chitosan on the production of cytokines such as interleukin-2 (IL-2), interferon-$\gamma$ (IFN-$\gamma$), interleukin-4 (IL-4), and interleukin-10 (IL-10) in mice. The culture supernatants of splenocytes exposed with chitosan alone or chitosan plus cell stimulants, lipopolysaccharide (LPS), concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) were harvested to assay IL-2, IFN-$\gamma$, IL-4, and IL-10 production. IL-2, IFN-$\gamma$, and IL-4 from splenocytes exposed to chitosan showed a greater increase compared to the PBS control group. IL-2 and IFN-$\gamma$ levels in the culture supernatants from splenocytes exposed to LPS+chitosan were higher than those of the groups exposed to LPS alone. IL-4 and IL-10 levels in the culture supernatants from splenocytes exposed to LPS+chitosan were lower than those of the groups exposed to LPS only. These findings demonstrate that chitosan upregulates the immune responses by Th1 cytokines (IL-2 and IFN-$\gamma$) and downregulates those by Th2 cytokines (IL-4 and IL-10) in LPS-associated immunity. These results show the potential of its usefulness for balancing the Th1/Th2 immune response, if more research results were accumulated.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.23 no.2
• /
• pp.75-81
• /
• 2017

Modified atmosphere packaging (MAP) of vacuum, 60% $N_2/40%$ $CO_2$, 100% $N_2$ and 100% $CO_2$ were examined to preserve fried fish cakes and extend their shelf life. When product packages in air were stored at 5, 10, and $15^{\circ}C$ with measurement in quality attributes, aerobic bacterial growth was found to be primary quality factor to determine the shelf life of the product. Huang's model was adopted to obtain the parameters for use in shelf life determination for a variety of packaging and storage conditions. Temperature dependence expressed in Arrhenius equation showed activation energies of 139.4 and 41.8 kJ/mol for inverse of lag time and growth rate of the microbial spoilage, respectively. MAP of 100% $CO_2$ could double the product shelf life at $10^{\circ}C$ compared to air package. High $CO_2$ concentration MAP at low temperature was found to be effective to prolong the shelf life.

• Korean Journal of Clinical Laboratory Science
• /
• v.52 no.3
• /
• pp.221-228
• /
• 2020

Ochrobactrum anthropi is a non-fermentative oxidative gram-negative bacillus that produces oxidase. Distinguishing a mixed culture with non-fermenting bacteria having a similar appearance and oxidase-positive is difficult, and there is a limit to accurate identification with a biochemical identification system. This paper proposes that the Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Platform (MALDI-TOF) method is useful for classifying bacteria that are difficult to identify using biochemical testing methods. As a result of analyzing five cases of O. anthropi examined using MicroScan, it took 6.5 days to the final report, which was 3.5 days more than the 3.0 days of E. coli. The pus sample in patient 5 was a mixed infection with Achromobacter xylosoxidans, and it took 11.3 days because of multiple subculture and retests. Four patients were over 60 years old with an underlying disease, and the possibility of opportunistic and nosocomial infections could not be excluded. Among them, samples collected after 92 days of hospitalization were resistant to imipenem and meropenem. Therefore, an examination using the MALDI-TOF method will be useful for the rapid and adequate treatment of patients with difficult identification, such as O. anthropi.

• Korean Journal of Microbiology
• /
• v.50 no.3
• /
• pp.210-215
• /
• 2014

Pseudomonas nitroreducens TX1 was isolated from a rice field drainage in Taiwan. The bacterium is of special interest because of its capability to use a group of nonionic surfactants such as alkylphenol polyethoxylates even at high concentrations as a sole carbon source. In this study, a small cryptic circular plasmid, pTX1, was characterized from P. nitroreducens TX1. It is 2,286 bp in length with a GC content of 63.3% and harbors three open reading frames, $Rep_{pTX1}$ and functionally unidentified ORF1 and ORF2. The predicted $rep_{pTX1}$ gene product is homologous to Rep proteins of plasmids belonging to the pC194/pUB110 family, which is predominantly found in Gram-positive bacteria and is known to replicate by the rolling-circle mechanism. The copy number of pTX1 was estimated to be about 150 in each cell. Based on the genetic fingerprints and comparison with other plasmids, it is concluded that pTX1 replicates by a rolling circle mechanism which is rarely found for Pseudomonas plasmids.

• Applied Biological Chemistry
• /
• v.40 no.6
• /
• pp.556-560
• /
• 1997

The removal efficiency of COD and the production of ${\delta}-aminolevulinic$ acid (ALA) were concurrently investigated for both purifying the soybean curd wastewater of high BOD and utilizing the wastewater as a renewable substrate of ALA production using Rhodobacter capsulatus KK-10. Its wastewater was a favorable media for the growth of photosynthetic bacteria in terms of its environmental characteristics having COD/BOD rate of 0.98, ratio of BOD : N : P=100 : 6 : 4, BOD/N ratio of 17.2, lactic acid of 1,080 ppm. Its COD value wastewater was decreased to 94% and dry cell weight was approached to about 1.2 g/l after cultivation of the photosynthetic bacteria for 4 days. By the addition of 15 mM levulinic acid (LA) into the wastewater at the middle log phase of cell growth, the amount of ALA secreted was 55 mg/l. The ALA production was considerably increased to 114 mg/l under the cultural condition of 15 mM supplementations of glycine and succinate with LA at the same period. Furthermore the maximum ALA production of 120 mg/l and COD removal efficiency of 92% were accomplished in the soybean curd wastewater enriched with one addition of 15 mM LA and three serial additions 15 mM ALA precursors.