• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.85-91
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• 2014

Deoxynivalenol (DON) and related trichothecene mycotoxins are extensively distributed in the cereal-based food and feed stuffs worldwide. Recent climate changes and global grain trade increased chance of exposure to more DON and related toxic metabolites in poorly managed production systems. Monitoring the biological and environmental exposures to the toxins are crucial in protecting human and animals from toxicities of the hazardous contaminants in food or feeds. Exposure biomarkers including urine DON itself are prone to shift to less harmful metabolites by intestinal microbiota and liver metabolic enzymes. De-epoxyfication of DON by gut microbes such as Eubacterium strain BBSH 797 and Eubacterium sp. DSM 11798 leads to more fecal secretion of DOM-1. By contrast, most of plant-derived DON-glucoside is also easily catabolized to free DON by gut microbes, which produces more burden to body. Phase 2 hepatic metabolism also contributes to the glucuronidation of DON, which can be useful urine biomarkers. However, chemical modification could be very typical depending on the anthropologic or genetic background, luminal bacteria, and hepatic metabolic enzyme susceptibility to the toxins in the diet. After toxin exposure, effect biomarkers are also important in estimating the linkage and mechanisms of foodborne diseases in human and animal population. Most prominent adverse effects are demonstrated in the DON-induced immunological and behavioral disorders. For instance, acutely elevated interleukin-8 from insulted gut exposed to dietaty DON is a dominant clinical biomarker in human and animals. Moreover, subchronic exposure to the toxins is associated with high levels of serum IgA, a biological mediator of IgA nephritis. In particular, anorexia monitoring using mouse models are recently developed to monitor the biological activities of DON-induced feed refusal. It is also mechanistically linked to alteration of serotoin and peptide YY, which are promising biomarkers of neurological disorders by the toxins. As animal-alternative biomonitoring, huamn enterocyte-based assay has been developed and more realistic gut mimetic models would be useful in monitoring the effect biomarkers in resposne to toxic contaminants in the future investigations.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.652-662
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• 2018

Diarrhea is a global disease with a high morbidity and mortality rate in children. In this study, 25 fecal samples were collected from children under 5 years old. Seven samples had been taken from healthy children without diarrhea and marked as the healthy control group; eight samples had been sampled from children with diarrhea caused by dyspepsia and defined as the non-infectious group; and ten samples had been taken from children with diarrhea induced by intestinal infections and identified as the infectious group. We detected the microbial communities of samples by using high-throughput sequencing of 16S rRNA genes. The proportion of aerobic and facultative anaerobic microbes in samples of the infectious group was much higher than in the non-infectious group. In addition, the relative abundance of Enterococcus in the healthy control group was significantly higher than in the non-infectious group and infectious group. This can be used as a potential diagnostic biomarker for diarrhea.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.3
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• pp.539-549
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• 1996

Large bowel cancer correlates tightly to dietary factors such as dietary fiber and fat. Dietary fiber prevents the large bowel cancer in different modes of action which depend upon physicochemical and fermentable properties. Water-soluble fiber is fermented easily by intestinal microbes producing short chain fatty acids ; in contrast, water-insoluble fiber occurs effectively more rapid transit time due to greater bulk of gut content, though it is unfermentable. Not only short chain fatty acid is utilized in the proximal and distal colon as primary energy source, but also it lowers pH in the colon to normalize cellular differentiation and helps to stimulate peri staltic movement by acting as an osmotic laxative. In particular, butyric acid may also regulate gene expression and cell growth, though it is an important respiratory fuel for the colonocyte. Since dietary fiber and non-digestible oligosaccharides are the major source of butyric acid, this provides a possible link between dietary fiber and oligosaccharide and prevention of large bowel cancer. But, as with many links between dietary fiber and large bowel cancer, a direct casual association has not been established. In addition, RDA of dietary fiber which is 20~25g/day for adult Japanese, appears to be reasonable for the defecation once daily and the prevention of large bowel cancer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.4
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• pp.563-569
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• 2013

This study was carried out to investigate the dose-response of chitooligosaccharide (with a molecular weight of 1~3 kDa) on antimicrobial activity and lipid lowering functions in rats. Sprague-Dawley male rats were given experimental diets containing 0 (control), 0.5, 2, or 5% chitooligosaccharide (COS) for 5 weeks. Weight gain and food intake were significantly lower in rats fed 5% COS than control rats and rats fed 0.5 and 2% COS. The numbers of fecal bacteria, including bifidobacteria, lactobacilli, bacteroides, total anaerobes, and total aerobes, which reflect gut microbiota, were significantly decreased in rats fed 5% COS. Plasma triglyceride concentrations significantly decreased in a dose-dependent manner in rats fed 2% or 5% COS, while plasma total cholesterol was not significantly different among groups. The hepatic concentration of triglycerides was lower in rats fed 5% COS, and fecal triglycerides significantly increased in rats fed 5% COS. These results indicate that 5% COS supplementation in a diet may exert antimicrobial activity in vivo, and inhibit the proliferation of typical gut microbes, while lowering lipids.

• Journal of the Korean Wood Science and Technology
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• v.46 no.6
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• pp.713-725
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• 2018

Lower termites require symbiotic microbes in their gut. The microbial communities in the termites must adapt to the termite temperature. Reticulitermes speratus KMT001 from Bukhan Mountain in Seoul may require a special symbiotic microorganisms for growth in low temperature Korean habitat. A metagenomics analysis showed a dramatic change in the symbiotic bacterial flora in the gut of R. speratus KMT001 in response to low temperatures of $4^{\circ}C$ or $10^{\circ}C$. Elusimicrobia, which are endosymbionts of flagellate protists, is the dominant phylum in the termite gut at ${\geq}15^{\circ}C$ but its population decreased drastically at low temperature. Four representative bacterial strains isolated from R. speratus KMT001 in a previous study produced maximum ${\beta}$-glucosidase levels within the temperature range of $10^{\circ}C-30^{\circ}C$. Elizabethkingia sp. BM10 produced ${\beta}$-glucosidase specifically at $10^{\circ}C$. This strain supported the existence of symbiotic bacteria for the low temperature habitat of the termite. This identified bacterium will be a resource for studying low temperature adaptation of termites, studying the gene expression at low temperatures, and developing an industrial cellulase at low temperature.

• Korean Journal of Poultry Science
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• v.49 no.2
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• pp.125-137
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• 2022

This study aimed to determine the effects of dietary microalgae (Tetradesmus sp. (TO)) on intestinal immunity and microbiota of pre-starter broilers. One hundred and twenty 1-day-old birds (Ross 308) were allocated to two dietary treatment groups with six blocks in a randomized complete block design. The two experimental diets consisted of a corn-soybean meal-based basal diet and a diet with 0.5% TO powder instead of cornstarch in the basal diet. After feeding the experimental diets for ten days, all birds' body weight and feed intake were measured, and representative eight birds were selected from each treatment group. Small intestinal lamina propria cells were isolated using flow cytometry to examine the frequency of immune cells. Cecal feces were harvested for 16s rRNA gut microbiota analysis and fecal IgA levels. Here, we found that 0.5% TO supplementation increased CD3⁺CD4⁺ T cells in the small intestine, but decreased CD3⁺CD8⁺ T cells in the small intestine. Gut microbial analysis showed that TO supplementation significantly increased the alpha diversity of the gut microbiome. Taxonomic analysis showed that TO treatment increased the abundance of Firmicutes and decreased that of Bacteroidetes at the phylum level. The distribution of Enterobacteriaceae containing many harmful bacteria at the family level, was lower in the TO group. In the LEfSe analysis, the TO group had a significantly enriched abundance of Agathobaculum at the genus level. Overall, results show that Tetradesmus sp. supplementation influences intestinal T-cell immunity and induces the expansion of beneficial gut microbes in pre-starter broiler chickens.

• Toxicological Research
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• v.23 no.1
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• pp.47-53
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• 2007

Amygdalin is a cyanogenic glycoside which is commonly found in almonds, bamboo shoots, and apri-cot kernels, and peach kernels. Amygdalin was first hydrolysed into prunasin, then degraded into cyanohydrin by sequential two-stage mechanism. The objective of this study was to examine the amygdalin decomposition and cyanide formation at various in vitro conditions, including acid, enzyme and anaerobic microbes (AM) in human feces (HF). In acid hydrolysis mimicking gastric environment, amygdalin was degraded to cyanide up to 0.2% in specific pH. In contrast, enzyme assay showed higher cyanide generation either by ${\beta}$-glucosidase, or by incubation with microbe. In conclusion, we are convinced of cyanide generation are occurred mainly by microbiological activities of the gut flora up to 41.53%. After ingestion with some staff, the degree and site of degradation in an organism is a key parst of regulatory decision making of that staff.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.10
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• pp.1505-1512
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• 2005

Bile salt deconjugation is the most biologically significant reaction among the bacterial alterations of bile acids in the gastrointestinal tract of human and animal. The responsible enzyme, bile salt hydrolase (BSH), catalyzes the hydrolysis of glycineand/or taurine-conjugated bile salts into amino acid residues and deconjugated bile acids. Herein we review current knowledge on the distribution of BSH activity among various microorganisms with respect to their biochemical and molecular characteristics. The proposed physiological impact of BSH activity on the host animal as well as on the BSH-producing bacterial cells is discussed. BSH activity of the probiotic strains is examined on the basis of BSH hypothesis, which was proposed to explain cholesterol-lowering effects of probiotics. Finally, the potential applications of BSH research are briefly discussed.

• Journal of Korean Academy of Dental Administration
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• v.6 no.1
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• pp.1-10
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• 2018

Prior to the end of the 20th century, microorganism research was limited to culture and has since been revolutionized by genetic analysis. Microorganisms, including bacteria, can cause disease, but most of them are commensal microorganisms in our bodies. This knowledge changes the pathological approach to infectious diseases and lends to a new perspective on the effects of gut and oral microorganisms on disease and health. The oral cavity, particularly the periodontal pocket, is considered to be a reservoir of microbes that cause disease, and oral microbial control is becoming more important. In this review, I will examine the changes in the microbiological revolution and the meaning of oral healthcare management based on those changes.

• Clinical and Experimental Pediatrics
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• v.60 no.5
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• pp.145-150
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• 2017

Purpose: The gut microbiota can influence several diseases through immune modulation; however, the exact role of microbes such as Clostridium difficile and the relationship between microbiota colonization and allergic diseases are not well known. This study aimed to determine the relationship between C. difficile colonization and/or infection (CDCI) during infancy and allergic diseases during early childhood. Methods: Infants 1-12 months of age presenting changes in bowel habits for more than 2 weeks were enrolled in this study. After dividing them into 2 groups according to the presence and absence of C. difficile, the risk of allergic disease development during childhood was identified and compared. Results: Sixty-five patients were included in this study; 22 (33.8%) were diagnosed with CDCI. No significant differences were observed in baseline characteristics between the C. difficile-positive and-negative groups except for antibiotic exposure (22.7% vs. 60.5%, P=0.004). Compared to the C. difficile-negative group, the risk of developing at least one allergic disease was higher in the C. difficile-positive group after adjusting other variables (adjusted odds ratios, 5.61; 95% confidence interval, 1.52-20.74; P=0.007). Furthermore, food allergies were more prevalent in the C. difficile-positive group (P=0.03). Conclusion: CDCI during infancy were associated with a higher risk of developing allergic diseases during early childhood. These results suggest that CDCI during infancy might reflect the reduced diversity of the intestinal microbiota, which is associated with an increased risk of allergic sensitization. To identify the underlying mechanism, further investigation and a larger cohort study will be needed.