Enteropathogenic Escherichia coli (EPEC) have developed survival strategies to evade host defense systems. The intracellular level of guanosine tetraphosphate (ppGpp) controlled by RelA and SpoT can mediate immune evasion of EPEC. However, the impact of ppGpp-defective EPEC infection on phagocytes remains unknown. In this study, we report that disrupting relA and spoT of EPEC E2348/69 strain promotes its phagocytosis in porcine macrophages. Our experimental analysis showed that both uptake and killing of an E2348/69 ΔrelAΔspoT mutant by macrophages were increased compared to those of wildtype strain. These results suggest that ppGpp plays an essential role in evading phagocytosis during EPEC pathogenesis.

We investigated the epidemiological characteristics of the antimicrobial resistant Enterococcus isolates from the four major rivers of Korea in 2012. A total 316 surface water samples were collected from three distinct sites (nearby livestock farms, tributaries, and major rivers) at two different seasons (dry season: n = 76, wet season: n = 240). A total 654 bacterial cells were isolated from samples and their genus distribution were determined. We found that Gram-negative bacteria including various genera were prevalent (n = 522, 79.8%), and Enterococcus was the most common genus of Gram-positive bacteria (n = 119, 18.2%). The isolation rate of Gram-negative bacteria was higher in wet season, whereas that of Enterococcus isolates was higher in dry season. The prevalence of Enterococcus isolates was also higher nearby livestock farms than on tributaries and main rivers. Since Enterococcus isolate is a key indicator for animal fecal contamination, the following experiments focused on this microorganism. As compared to a previous report in 2006, the resistance rates in E. faecium to erythromycin (40.0% to 69.9%) and chloramphenicol (0% to 16.4%) were increased, whereas those to penicillin (56.0% to 4.1%) and teicoplanin (36.0% to 0%) were decreased. We also found that antimicrobial-resistant (AMR) E. faecium isolates from rivers and livestock samples shared similar pulsed-filed gel electrophoresis (PFGE) profiles, validating the transmission of AMR Enterococcus isolates from livestock to river. Taken together, this study provides us with detailed information about bacterial contamination status in four major rivers, and highlights the changes in AMR pattern of Enterococcus isolates, which are expected to have originated from livestock.

Enteropathogenic Escherichia coli (EPEC) is one of the etiological agents that causes diarrhea in weaning pigs. In this study, we report that mutating both relA and spoT genes in EPEC E2348/69 can promote bacterial clearance in porcine gastrointestinal tract (GIT). Our experimental analyses showed that an E2348/69 ΔrelAΔspoT mutant strain was not detected in porcine feces after 1 day post-infection (dpi), whereas its parental strain was continuously detected in porcine feces within 10 dpi. Histologic assessment revealed that the mutant strain was unable to induce moderate pathologic lesions in porcine GIT when compared to those with the wildtype strain. Taken together, our data suggest that the relA and spoT genes in EPEC play an important role in bacterial survival and pathogenesis in porcine GIT.

A eukaryotic marine microalga was isolated from Jungmun Saekdal Beach, Jeju Island, Korea and an integrated approach, including molecular phylogeny and morphology, was used to determine its taxonomical status. Molecular phylogenetic evidence inferred from the small subunit (SSU) 18S rRNA sequence and internal transcribed spacer (ITS) secondary structure analysis clearly showed that the isolate belonged to the recently described species, Jaagichlorella roystonensis. Distinctive morphological keys of the species were also observed by light microscopy and scanning/ transmission electron microscopy (S/TEM). In this study, a Korean marine J. roystonensis species was described for the first time and was subsequently added to the national culture collections in Korea.

A eukaryotic microalga was isolated from seawater in Janghang Harbor, Korea and its morphological, molecular, and physiological characteristics were investigated. Due to its simple morphology, no distinctive characters were found by morphological observation, such as light microscope or scanning/transmission electron microscopy (S/ TEM). However, molecular phylogenetic evidence inferred from the concatenated small subunit (SSU) 18S rRNA and internal transcribed spacer (ITS) sequence data indicated that the isolate belonged to the newly described Micractinium singularis. Furthermore, it was clustered with Antarctic Micractinium strains and it also showed a psychrotolerant property, surviving at temperatures as low as 5°C. However, its optimal growth temperatures range from 15°C to 25°C, indicating that this microalga is a mesophile. Additionally, gas chromatography-mass spectrometry (GC/MS) analysis showed that the isolate was rich in nutritionally important omega-3 polyunsaturated fatty acid, and high-performance liquid chromatography analysis (HPLC) revealed that the high-value antioxidant lutein was biosynthesized as an accessory pigment by this microalga, with glucose as the major monosaccharide. Therefore, in this study, a Korean marine M. singularis species was discovered, characterized, and described. It was subsequently added to the national culture collections.

Salmonella is one of the most important bacterial pathogens responsible for many zoonotic food-related infectious diseases. Quantitative detection of the foodborne Salmonella contamination in various food sources is therefore critical for preventing the related disease outbreaks. In this study, we developed and evaluated a reliable real-time polymerase chain reaction (RT-PCR) assay to detect the Salmonella contamination quantitatively. The experimental results showed that our invA gene-specific quantitative RT-PCR (qRT-PCR) assay provides a strong correlation between the Cq values and the direct plate counts of Salmonella species in the artificially formulated samples. Further study may be necessary to identify more accurate correlation and equation that can apply to Salmonella spp.

Excessive intake of red meat has been associated with colon carcinogenesis. The effect of hemin and zinc on colon carcinogenesis was investigated in male ICR mice. After acclimation for 1 week, five-week-old mice received three s.c. injections (0-2nd weeks of the experiment) of azoxymethane (AOM; 10 mg/kg b.w.) weekly and were treated by 2% dextran sodium sulfate (DSS) in drinking water for the next 1 week to induce aberrant crypt foci (ACF). Mice were fed on AIN-76A purified rodent diet for 6 weeks. There were three experimental groups; control, hemin, and hemin + zinc groups. The daily oral doses of hemin and zinc were 534 mg/kg and 55 mg/kg b.w., respectively. After staining colonic mucosa with 0.2% methylene blue, the ACF, aberrant crypts (AC), and polyps were counted. Lipid peroxidation in liver was evaluated by thiobarbituric acid-reactive substances (TBARS) assay. The numbers of AC, ACF, large ACF (i.e., ≥4 AC/ACF), and polyps in the hemin group were higher than those in the control group. In hemin + zinc group, the numbers of AC, ACF, large ACF were significantly lower compared to the hemin or control groups (p < 0.05), and the number of polyps was also significantly lower compared to that in the hemin group (p < 0.05). The TBARS level in the livers of the hemin + zinc group was significantly lower than that of the hemin group (p < 0.05). These results suggest that hemin enhances colon carcinogenesis and that co-treatment with zinc can protect against the induction of colon carcinogenesis.

Red meats are important animal foods because of their nutritional aspects, but the over-consumption of red meat produces reactive oxygen species (ROS) caused by heme iron and induces colorectal cancer. The effect of orally administered hemin and calcium provided in drinking water for 6 weeks on colon carcinogenesis was observed in male ICR mice. After the mice were acclimated for 1 week, they received three subcutaneous azoxymethane (AOM, 10 mg/kg b.w.) injections weekly and were provided with 2% dextran sodium sulfate (DSS) via drinking water for the next week. The mice were divided into three groups: the control, hemin, and hemin + calcium groups. The orally administered daily dose of hemin was 2 g/kg b.w., and 0.05% calcium was provided daily via drinking water. Colonic mucosa samples were stained with methylene blue, and then, the numbers of aberrant crypt (AC) and aberrant crypt foci (ACF) were counted. Lipid peroxidation in feces was estimated by thiobarbituric acid-reactive substances (TBARS) assay. The total numbers of AC and ACF per colon in the hemin group were significantly higher than those in the control group. Calcium treatment significantly decreased the numbers of ACF and AC in the colon of mice. The TBARS value in the feces of the hemin + calcium group was significantly lower than that in the feces of the hemin group. These results showed that hemin enhances the formation of pre-neoplastic lesions in the colon of mice and that calcium decreases the risk of colon carcinogenesis.

Colorectal cancer (CRC) is the third most prevalent cancer in the world, and heme iron is known to promote the CRC in an animal model. This study was conducted to investigate the effects of ascorbic acid in the presence of hemin on the formation of pre-neoplastic lesions induced by azoxymethane (AOM)/disodium sulfate (DSS) in mice. After acclimation for 1 week, five-week old mice received three s.c. injections (0-2 weeks of the experiment) of AOM [10 mg/kg body weight (BW)] weekly and were treated with 2% DSS in drinking water for the next week to induce aberrant crypt foci (ACF). All animals were fed the AIN-76A purified rodent diet for experimental period of 6 weeks. Experimental groups were then divided into three groups: carboxymethylcellulose (CMC) alone (control), CMC + Hemin, CMC + Hemin + ascorbic acid (AA). The CMC was used as a solvent for hemin. The daily doses were 534 mg/kg BW hemin and 246 mg/kg BW ascorbic acid administered orally. After the colonic mucosa were stained with methylene blue, aberrant crypt foci (ACF), aberrant crypt (AC) and polyps were counted. Lipid peroxidation in liver was evaluated by the thiobarbituric acid-reactive substances (TBARS) assay. The numbers of ACF, AC and large ACF (≥4 AC/ACF) per colon increased in the hemin group compared to the control group, while they decreased significantly in the hemin + ascorbic acid group compared to the control group or hemin group (p<0.01). The number of polyps/colon in the hemin + AA group was significantly decreased compared to the hemin group (p<0.05). In the liver, the TBARS value of the hemin group was significantly higher than that of the control group (p<0.01). Additionally, the TBARS value of the hemin + AA group decreased slightly compared to that of the hemin group. Taken together, these results suggest that hemin can promote colon carcinogenesis in a mouse model and that ascorbic acid has a protective effect against hemin-promoted colon carcinogenesis.

Turmeric is known for its ability to enhance immunity via anti-inflammatory and anti-oxidant effects. Salmonella enterica species contain a large number of pathogenic serotypes that are adapted to a broad range of vertebrate hosts. Our previous study revealed that bioprocessed polysaccharides from the liquid culture Lentinus edodes fungal mycelia containing turmeric (BPP-turmeric) is able to alter chicken macrophage responses and increases chick survival against Salmonella enterica infection. In this study, we examined the immunomodulatory effects of BPP-turmeric on the porcine macrophage 3D4/31 cell line infected with Salmonella enterica subsp. enterica serovar Choleraesuis (S. Choleraesuis) or S. Enteritidis. Our experimental analyses demonstrated that BPP-turmeric (i) does not alter phagocytic and killing activity of 3D4/31 against either Salmonella serotypes, but that it (ii) represses mRNA transcription of interleukin (IL)-6, IL-8, and tumor necrosis factor α in response to Salmonella infection. Collectively, these results imply that BPP-turmeric has an immunomodulatory effect that represses pro-inflammatory cytokine expression in porcine macrophages, suggesting that it may protect swine from salmonellosis via controlling Salmonella-induced hyperinflammation.

Excessive iron can promote the production of free radicals, thereby leading to harmful effects on cancer and aging. Ascorbic acid is not only an antioxidant but also a co-factor of iron absorption. The effect of iron-overload with ascorbic acid on experimental colon carcinogenesis was investigated in male ICR mice. Animals were treated weekly with azoxymethane (AOM, 10 mg/kg b.w.) at 0, 1, and 2 week and then drunk 2% dextran sodium sulfate (DSS)-containing water for the next 1 week. There were four experimental groups: carboxymethylcellulose (CMC) alone (control), CMC + ascorbic acid (AA), CMC + Fe, CMC + Fe + AA. The animals fed on AIN-76A purified rodent diet for six weeks. AA or Fe2O3 at the dose of 450 mg/kg b.w. were daily and orally treated for 6 weeks. The colonic mucosa was stained with methylene blue and then aberrant crypt foci (ACF) and polyps were counted. Thiobarbituric acid-reactive substances (TBARS) in serum and liver were determined. Iron concentration in liver was measured by inductively coupled plasma spectrophotometer. Fe-overload with AA strongly increased liver iron contents compared to control or Fe group (p<0.05). There were no significant differences in the number of ACF or polyps among all groups, although ironoverloaded groups had slightly higher numbers compared with the control or AA group. TBARS values in the liver were increased in the iron-overloaded groups compared to control and AA only group (p<0.05), but serum TBARS values were not changed. These results indicate that the excessive iron treatment did not affect the experimental colon carcinogenesis regardless of presence of AA in mice.

We performed a survey for flavivirus infection and distribution of Aedes albopictus that known as Zika and Dengue virus vector using black–light trap and BG-sentinel trap around urban area in Korea. Mosquitoes were collected in 27 cities during March to November (twice a month) year 2016. Total numbers of mosquitoes collected 102,102 including 19 species 8 genera during collecting period. Total 21,467 Ae. albopictus was collected that 20,961(24.3%) by BG-sentinel trap and 506 (3.2%) by Black-light trap in urban area. Trap index(trap/night) of Ae. albopictus was showed highest in Hamyang (TI:992.3) and lowest in Taebaek (TI:0.3) there was only collected by Black-light trap. A total of 894 pools from all collecting Ae. albopictus were performed a Flavivirus detection. Flavivirus was not detected during study period. This study may provide basic information for surveillance of imported diseases (include Zika virus) and vectors in Korea.

Shiga toxin-producing Escherichia coli (STEC) is a major foodborne bacterial pathogen that causes many zoonotic diseases such as mild diarrhea, hemorrhagic colitis, and a life-threatening hemolytic uremic syndrome. STEC produces one or more Shiga toxins (Stxs) with or without other virulence factors including the locus of enterocyte and effacement pathogenicity island and the 60-MDa plasmid. Because cattle are the principal reservoirs of STEC, the consumption of undercooked meat and dairy products contaminated with bovine feces is the most common transmission route of STEC in human infections. To understand the epidemiology of STEC infection in South Korea, the prevalence of STEC among bovine feces, meat products, and human patients was reviewed in this study. We found that (i) the prevalence of STEC O157:H7 (hereafter referred to as O157 STEC) isolates was generally decreased, whereas non-O157 STEC isolates be increased among bovine feces and meat products from 2000 to 2012 and (ii) no severe human outbreaks occurred. Instead, 50 to 100 sporadic cases of STEC infection per year have been reported in asymptomatic human patients or patients with mild diarrhea. Key words: Shiga toxin-producing, Escherichia coli, STEC, prevalence, South Korea

Ixodid ticks are notorious as the vector of severe fever with thrombocytopenia syndrome virus (SFTSV) in Korea. To confirm the transovarial transmission of SFTSV, we collected blood-fed adult ticks from animals in SFTS case reported area of Jeju island in 2015. A total of 476 ticks were collected from four host animal species, horse (81.3%), dog (9.0%), roe deer (7.1%) and wild boar (2.5%). They were identified as 1 genus and 2 species, Haemaphysalis longicornis (87.8%) and H. flava (12.2%). Among them, 131 adults hatched their eggs successfully. The body weight of females was highly correlated with the number of egg masses laid (P < 0.05). We confirmed that one adult H. flava was infected with SFTSV and its infection rate was 0.77%. The eggs of the SFTSV-infected adults also were infected with SFTSV and its transovarial transmission was confirmed. This result suggests that the parent generation of H. flava could transmit SFTSV transovarially into their F1 progeny and H. flava might be one of major vectors of SFTSV in Korea.

Colorectal cancer is one of the most common types of cancer in men and women who consume a Western diet. We investigated the inhibitory effect of selenium (sodium selenite, Na2SeO3) and selenium nanoparticles (nano-Se) on experimental colon carcinogenesis in ICR mice. After a 1-week acclimation, 6-week-old mice received three intraperitoneal (i.p.) injections (experimental week 0-2) of azoxymethane (AOM, 10 mg/kg body weight, b.w.), followed by 2% dextran sodium sulfate (DSS)-containing drinking water for the next 1 week. The three groups (10 mice/group) were orally administered either distilled water (control), selenium (1.7 ppm), or nano-Se (1.7 ppm) daily for 8 weeks. The numbers of aberrant crypt foci (ACF), aberrant crypt (AC), and tumorous lesions were measured in colonic mucosa. Se and nano-Se treatments significantly decreased the number of ACF, AC, and tumorous lesions compared with the control. However, there was no significant difference between the selenium and nano-Se groups. The glutathione peroxidase (GSH-Px) activity in the liver and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in serum, were high in the selenium and nano-Se groups, while thiobarbituric acid reactive substance (TBARS) level was low in both Se and nano-Se groups when compared with that in the control group. These findings indicate that selenium and nano-Se showed similar protective effects against colon carcinogenesis by inhibiting the development of ACF and tumorous lesions in mice.

Iron-overload can cause harmful effects such as cancer and aging via promoting the production of free radicals. The effect of orally administered nano-Fe overload with ascorbic acid on colon carcinogenesis was investigated in male ICR mice. After a 1-week acclimation, 5-week-old mice received three intraperitoneal injections (experimental week 0-2) of azoxymethane (AOM, 10 mg/kg body weight) weekly, followed by 2% dextran sodium sulfate (DSS) in drinking water for the next 1 week to induce aberrant crypt foci (ACF). Animals were divided into four groups; carboxymethylcellulose (CMC) alone (control), CMC + ascorbic acid (AA), CMC + nano-Fe (NFe), and CMC + NFe + AA groups. Animals were fed an AIN-76A purified rodent diet and daily administrated oral doses of 450 ppm each of nano-Fe and AA combination for 6 weeks. The colonic mucosa was stained with 0.5% methylene blue, and then the ACF and polyps were counted. Lipid peroxidation in the serum and liver was evaluated using the thiobarbituric acid-reactive substances (TBARS) assay. Iron concentration in the liver was measured using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Iron concentration in the liver of the NFe-overloaded groups was higher than that of the control (p<0.05). AA treatment increased the iron concentration in the liver. The number of ACF was not significantly different among all the groups. The number of polyps in all the NFe-treated groups was slightly higher than that in the control group and AA only-treated group. The serum TBARS was not significantly different among all the groups, but that in the liver was higher in all the NFe-treated groups than it was in the control group (p<0.05). These results indicate that the additional NFe treatment did not affect the experimental colon carcinogenesis in mice regardless of the presence of ascorbic acid.

Bioenergetics has been defined as the biology of energy transformations and energy exchanges within and between living organisms and their environment; this field now includes the concept of bioenergetic medicine, e.g., therapeutic approaches involving biophotons. QELBY® powder is a patented quantum energy-radiating material (patent No. 10-1172018), to be precise, a biologically active silicon dioxide-containing mineral powder that radiates reductive energy in infrared wavelength. In this study, we examined possible biological effects of indirect contact with QELBY® powder on various mammalian cell lines derived from macrophagic (MØ) and nonmacrophagic cells, including Raw 264.7 (mouse-derived MØ cell line), HD11 (chicken-derived MØ cell line), and HeLa (human cervical cancer cell line). Our comparison among the cells with and without indirect contact with QELBY® powder showed that this indirect contact significantly (i) increased the mitochondrial membrane potential (up to 1.36-fold) regardless of the cell type (p < 0.05), (ii) decreased the intracellular concentration of ATP in HeLa cells but not in the MØ-derived cells (p < 0.05), and (iii) protected DNA from damage during oxidative stress according to a standard comet assay (single-cell alkaline gel electrophoresis). Taken together, these results imply that indirect contact with QELBY® powder can make cells more metabolically active by increasing the mitochondrial membrane potential and by alleviating DNA damage caused by oxidative stress.