• Journal of Dairy Science and Biotechnology
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• v.32 no.2
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• pp.141-145
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• 2014

There is a burgeoning number of products on the market that contain probiotics, but do they do you any good? What exactly are probiotics? They have been defined as living organisms that, when ingested in sufficient quantities, provide health benefits beyond basic nutrition. They are often referred to as "friendly bacteria" or "good bacteria." Probiotics have been claimed, amongst other things, to (i) reduce the incidence of colon cancer and other diseases of the colon, such as IBS, (ii) stimulate the immune system, (iii) have anti-hypertensive and anti-cholesterolemic properties, (iv) mitigate against the effect of antibiotics on the intestinal microbiota, and (v) protect against gastrointestinal infections. However, the scientific basis for many of these claims is not well-established. Indeed, the European Food Safety Authority has denied the use of several health claims associated with probiotics, particularly those related to mitigation of diarrhea following consumption of antibiotics. Thus, there is a need for research on the mechanisms of action of probiotics. We have been mainly interested in the use of probiotics to control enteric infections. There are several possible modes of action to explain how probiotics may protect the host from enteric pathogens, including competitive exclusion and immunomodulation. We have shown that probiotics produce bioactive molecules that interfere with bacterial cell-cell communication (also called quorum sensing), and this results in a down-regulation of virulence genes that are responsible for attachment of the pathogen to the gastrointestinal epithelium. These bioactive molecules act on a variety of bacteria, including enterohemorrhagic and enterotoxigenic Escherichia coli, Salmonella, Clostridium difficile and Clostridium perfringens, and there is evidence that they can inhibit the formation of biofilms by Listeria monocytogenes. These bioactive molecules, which are peptidic in nature, can exert their effects not only in vitro but also in vivo, and we have shown that they mitigate against E. coli O157:H7 and Salmonella in mice and Salmonella and E. coli K88 infections in pigs. They can be delivered in foods such as yoghurt and maintain their activity.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1663-1665
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• 2008

Acyl-coenzyme A: cholesterol acyltransferase (ACAT) catalyzes cholesterol esterification and plays an important role in the intestinal absorption of cholesterol, hepatic production of lipoproteins, and accumulation of cholesteryl ester within cells. During the course of screening to find ACAT inhibitors from microbial sources, the present authors isolated pyripyropene A from Penicillium griseofulvum F1959. Pyripyropene A, an ACAT2-specific inhibitor, has already been produced from Aspergillus fumigatus. Yet, Aspergillus fumigatus is a pathogen and only produces a limited amount of pyripyropene A, making the isolation of pyripyropene A troublesome. In contrast, Penicillium griseofulvum F1959 was found to produce approximately 28 times more pyripyropene A than Aspergillus fumigatus, plus this report also describes the ideal conditions for the production of pyripyropene A by Penicillium griseofulvum F1959 and its subsequent purification.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2006.11a
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• pp.7-16
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• 2006

Poultry products including meat and eggs constitute a major protein source in the American diet and disease - causing pathogens represent major challenges to the poultry industry. More than 95 % of pathogens enter the host through the mucosal surfaces of the respiratory, digestive and reproductive tracts and over the past few decades, the two main mechanisms used to control diseases have been the use of vaccines and antibiotics. However, in the poultry industry, there are mounting concerns over the ability of current vaccines to adequately protect against emerging hyper - virulent strains of pathogens and a lack of suitable, cost effective adjuvants. Thorough investigation of the immunogenetic responses involved in host-pathogen interactions will lead to the development of new and effective strategies for improving poultry health, food safety and the economic viability of the US poultry industry. In this paper, I describe the development of immunogenomic and proteomic tools to fundamentally determine and characterize the immunological mechanisms of the avian host to economically significant mucosal pathogens such as Eimeria. Recent completion of poultry genome sequencing and the development of several tissue-specific cDNA libraries in chickens are facilitating the rapid application of functional immunogenomics in the poultry disease research. Furthermore, research involving functional genomics, immunology and bioinformatics is providing novel insights into the processes of disease and immunity to microbial pathogens at mucosal surfaces. In this presentation, a new strategy of global gene expression using avian macrophage (AMM) to characterize the multiple pathways related to the variable immune responses of the host to Eimeria is described. This functional immunogenomics approach will increase current understanding of how mucosal immunity to infectious agents operates, and how it may be enhanced to enable the rational development of new and effective strategies against coccidiosis and other mucosal pathogens.

• Journal of Animal Science and Technology
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• v.44 no.4
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• pp.491-498
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• 2002

The inhibitory effect of lactobacilli and bifidobacteria on the growth of typical intestinal pathogens, Escherichia coli and Salmonella typhimurium was studied. The degree of inhibition was measured by well disc assay and turbidimetry method. The strains which showed the higher antimicrobial activity were L. acidophilus La-5, L. acidophilus NCFM, L. casei Lc-01 on the average by using two different methods. The associative cultures were performed with selected 3 lactobacilli and 2 enteropathogens E. coli and S. typhimurium, respectively. Inhibition of pathogen began at 9hr after culturing so that viable counts was decreased rapidly. After 30hr incubation, there were no viable pathogens from the mixed culture. Under this experimental condition, the antimicrobial activity of lactic acid bacteria was not due to pH alone and supposed to different to the strains.

• Korean Journal of Microbiology
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• v.54 no.2
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• pp.149-151
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• 2018

Clostridium perfringens is a Gram-positive, rod-shaped, anaerobic, spore-forming pathogenic bacterium, which belongs to the Clostridiaceae family. C. perfringens causes diseases including food poisoning in vertebrates and intestinal tract of humans. Bacteriophages that can kill target bacteria specifically have been considered as one of control methods for bacterial pathogens. Here, we report a draft genome sequence of the bacteriophage CP3 effective to C. perfringens. The phage genome comprises 52,068 bp with a G + C content of 34.0%. The draft genome has 74 protein-coding genes, 29 of which have predicted functions from BLASTp analysis. Others are conserved proteins with unknown functions. No RNAs were found in the genome.

• Animal Bioscience
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• v.34 no.9
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• pp.1525-1531
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• 2021

Objective: The objective of this study was to evaluate the antimicrobial effects of fermented Maillard reaction products made by milk proteins (FMRPs) on Clostridium perfringens (C. perfringens), and to elucidate antimicrobial modes of FMRPs on the bacteria, using physiological and morphological analyses. Methods: Antimicrobial effects of FMRPs (whey protein plus galactose fermented by Lactobacillus rhamnosus [L. rhamnosus] 4B15 [Gal-4B15] or Lactobacillus gasseri 4M13 [Gal-4M13], and whey protein plus glucose fermented by L. rhamnosus 4B15 [Glc-4B15] or L. gasseri 4M13 [Glc-4M13]) on C. perfringens were tested by examining growth responses of the pathogen. Iron chelation activity analysis, propidium iodide uptake assay, and morphological analysis with field emission scanning electron microscope (FE-SEM) were conducted to elucidate the modes of antimicrobial activities of FMRPs. Results: When C. perfringens were exposed to the FMRPs, C. perfringens cell counts were decreased (p<0.05) by the all tested FMRPs; iron chelation activities by FMRPs, except for Glc-4M13. Propidium iodide uptake assay indicate that bacterial cellular damage increased in all FMRPs-treated C. perfringens, and it was observed by FE-SEM. Conclusion: These results indicate that the FMRPs can destroy C. perfringens by iron chelation and cell membrane damage. Thus, it could be used in dairy products, and controlling intestinal C. perfringens.

• Korean Journal of Microbiology
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• v.55 no.1
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• pp.64-66
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• 2019

Cutibacterium acnes is a member of normal flora of human skin, conjunctiva, intestinal tract, the external auditory canal as well as oral cavity. It has been identified as an opportunistic pathogen related to acne vulagris, endocarditis infections, sarcoidosis, brain abscess, periodontitis, and osteomyelitis of the humerus. C. acnes KCOM 1315 (= ChDC KB81) was isolated from a human jaw osteomyelitis lesion. Here, we present the complete genome sequence of C. acnes KCOM 1315.

• Parasites, Hosts and Diseases
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• v.57 no.3
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• pp.225-232
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• 2019

Innate lymphoid cells (ILCs) are key players during an immune response at the mucosal surfaces, such as lung, skin, and gastrointestinal tract. Giardia lamblia is an extracellular protozoan pathogen that inhabits the human small intestine. In this study, ILCs prepared from the lamina propria of mouse small intestine were incubated with G. lamblia trophozoites. Transcriptional changes in G. lamblia-exposed ILCs resulted in identification of activation of several immune pathways. Secretion of interleukin (IL)-17A, IL-17F, $IL-1{\beta}$, and interferon-${\gamma}$ was increased, whereas levels of IL-13, IL-5, and IL-22, was maintained or reduced upon exposure to G. lamblia. Goup 3 ILC (ILC3) was found to be dominant amongst the ILCs, and increased significantly upon co-cultivation with G. lamblia trophozoites. Oral inoculation of G. lamblia trophozoites into mice resulted in their presence in the small intestine, of which, the highest number of parasites was detected at the 5 days-post infection. Increased ILC3 was observed amongst the ILC population at the 5 days-post infection. These findings indicate that ILC3 from the lamina propria secretes IL-17 in response to G. lamblia, leading to the intestinal pathology observed in giardiasis.

• Journal of Environmental Health Sciences
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• v.48 no.3
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• pp.176-182
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• 2022

Background: The risk of imported infectious diseases has been increasing with the annual rise in the number of international travelers. Objectives: This study aims to analyze the distribution and characteristics of intestinal bacteria isolated in 2019 from residents of Chungcheongnam-do Province with experience of travelling overseas. Methods: Twenty-three former overseas travelers with diarrhea were analyzed to detect viruses and bacteria according to the Manual for Detection of Foodborne Pathogens at Outbreaks. Additionally, antibiotic susceptibility tests and 16s rRNA sequencing were performed. Results: Twenty-five strains of ten pathogens were isolated from 18 samples. Pathogenic E. coli was the most common at 57.7%, followed by Clostridium perfringens (15.4%), Campylobacter spp. (7.7%), and Salmonella spp. (7.7%). The serotype of Salmonella was confirmed as Salmonella Braenderup, II 9,46:g,[m],[s],t:[e,n,x]. Conclusions: It was confirmed that the major enteric bacterial pathogens isolated from overseas travelers in Chungcheongnam-do Province were pathogenic E. coli, as found in other studies. The study on Plesiomonas shigelloides is meaningful in that it is reported as a rare case of infection in Korea. Antibiotic resistance and 16s rRNA analysis were performed, which is expected to provide important basic data for the prevention of traveler's diarrhea.

• Korean Journal of Agricultural Science
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• v.49 no.1
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• pp.1-10
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• 2022

One hundred and twenty imprinting control region (ICR) mouse with initial body weights of 26 ± 2 g (5 weeks old) were assigned to six treatments for a two-week feeding trial to determine the effect of Pediococcus pentosaceus strains (PpS) which were isolated from three different types of Kimchi in ICR mice infected with Escherichia coli (Ec) or Salmonella Typhimurium (ST). Six groups constituted a normal control group without Ec or ST orally administrated (NC-; n = 20), a normal control group (NC+; n = 20), a group for which Lactobacillus plantarum was orally administrated (LP; n = 20), a group for which PpS A was orally administrated (PSA; n = 20), a group for which PpS B was orally administrated (PSB; n = 20), and a group for which PpS C was orally administrated (PSC; n = 20), the latter five groups constituted the Ec infected groups and the ST infected groups of 10 mice each. LP and PSC showed significantly (p < 0.05) improved growth performance compared to the other groups, except for NC- in the Ec infected mice group. NC+ showed significantly lower (p < 0.05) growth performance compared to the other groups, except for NC- in the ST infected mice groups. Regarding the Ec and Salmonella counts in the intestine, the LP and PSC groups had significantly lower (p < 0.05) counts than the NC+ and PSB groups. In conclusion, LP and PSC strains isolated from Kimchi can act as probiotics by inhibiting Ec and ST.