• Natural Product Sciences
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• v.19 no.4
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• pp.297-302
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• 2013

The current study was conducted to evaluate the antibacterial and antioxidant activities of the essential oil fraction from the roots of Angelica tenuissima Nakai and its main components. We extracted the essential oil fraction from the roots of A. tenuissima using steam distillation and isolated its main components. Their antibacterial activities were determined by broth dilution test against food-borne pathogenic bacteria. Antioxidant activities were evaluated by DPPH-scavenging assay and reducing-power test. Also tested was their ability to inhibit the growth of two gastrointestinal cancer cell lines, Caco-2 and MKN-45. The A. tenuissima oil fraction and its main components, ligustilide and butylidene phthalide exhibited marked inhibitory effects against most of the tested antibiotic-susceptible and antibiotic-resistant bacterial strains with minimum inhibiting concentrations (MICs) from $0.21{\pm}0.08$ to $3.60{\pm}0.89mg/ml$. They also showed growth-inhibiting activity against Caco-2 and MKN-45 cells. The oil fraction showed significant antioxidant activities in DPPH radical scavenging assay and reducing-power test. Taken together, A. tenuissima essential oil could be used as a safe additive for preventing food contamination by pathogenic bacteria. Additionally, its antioxidative activity and the ability to inhibit gastrointestinal carcinoma cell lines could increase its value for functional foods and prevention of cancer.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.129-134
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• 2002

To isolate probiotic lactic acid bacteria having superior inhibitory activities against animal gastro-intestinal pathogenic bacteria such as Salmonella gallinarum, Staphylococcus aureus and Escherichia coli, 130 strains were initially isolated from the small intestines of Korean native chickens and 7 lactic acid bacteria were finally selected. By using API CHL kit and 16S rRNA sequencing method, the selected lactic acid bacteria were found to be belonged to genus Lactobacillus except BD14 identified as Pediococcus pentosaceus. Especially, Lactobacillus pentosus K34 showed the highest resistancy to both of HCl and bile salt, as well as the highest inhibitory activities against S. gallinarum, S. aureus and E. coli. All the selected strains were sensitive to various antibiotics such as neomycin, erythromycin, cephalosporin, amoxicillin/clavulanic acid, ampicillin, oxytetracycline, but resistant to ciprofloxacin. All the selected strains except BL strain were resistant to colistin and streptomycin, and BD14, BD16, K34 strains were resistant to gentamicin.

• Journal of Dairy Science and Biotechnology
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• v.39 no.2
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• pp.51-62
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• 2021

Escherichia coli are the predominant facultative bacteria found in the gastrointestinal tract of animals and humans. Some strains of E. coli that acquire virulence factors and cause foodborne and waterborne diseases in humans are called pathogenic E. coli and can be divided into five pathotypes according to the virulence mechanism: EAEC, EHEC, EIEC, EPEC, and ETEC. Although selective media have been developed to detect E. coli, distinguishing pathogenic strains from non-pathogenic ones is difficult because of their similar biochemical properties. Therefore, it is very important to find a new and effective diagnostic method to identify pathogenic E. coli. With recent advances in molecular biology and whole genome sequencing, the use of polymerase chain reaction (PCR) is increasing rapidly. In this review paper, we provide an overview of pathogenic E. coli and present a review on PCR detection methods that can be used to diagnose pathogenic E. coli. In addition, the possibility of real-time PCR incorporating IAC is introduced. Consequently, this review paper will contribute to solving the current challenges related to the detection of pathogenic E. coli.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.276-286
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• 2020

Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. This study was conducted for the isolation of potential lactic acid bacteria (LAB) with probiotic properties from goat milk and yogurt. Several tests were conducted in vitro using the standard procedures for evaluating the inhibitory spectra of LAB against pathogenic bacteria; tolerance to NaCl, bile salt, and phenol; hemolytic, milk coagulation, and bile salt hydrolase activities; gastrointestinal transit tolerance; adhesion properties; and antibiotic susceptibility. Among 40 LAB strains screened according to culture characteristics, five isolates exhibited antagonistic properties. Three were identified as Pediococcus acidilactici, and two were identified as Enterococcus faecium, exploiting 16S rRNA gene sequencing. All the isolates succeeded in the gastrointestinal transit tolerance assay and successively colonized mucosal epithelial cells. Based on the results of these in vitro assays, both P. acidilactici and E. faecium can be considered as potential probiotic candidates.

• Journal of Animal Science and Technology
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• v.58 no.7
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• pp.26.1-26.11
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• 2016

The use of probiotics for human and animal health is continuously increasing. The probiotics used in humans commonly come from dairy foods, whereas the sources of probiotics used in animals are often the animals' own digestive tracts. Increasingly, probiotics from sources other than milk products are being selected for use in people who are lactose intolerant. These sources are non-dairy fermented foods and beverages, non-dairy and non-fermented foods such as fresh fruits and vegetables, feces of breast-fed infants and human breast milk. The probiotics that are used in both humans and animals are selected in stages; after the initial isolation of the appropriate culture medium, the probiotics must meet important qualifications, including being non-pathogenic acid and bile-tolerant strains that possess the ability to act against pathogens in the gastrointestinal tract and the safety-enhancing property of not being able to transfer any antibiotic resistance genes to other bacteria. The final stages of selection involve the accurate identification of the probiotic species.

• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.857-863
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• 2023

Pathogenic bacteria that colonize the human intestinal tract have evolved strategies to overcome acidic conditions when they pass through the gastrointestinal tract. Amino acid-mediated acid resistance systems are effective survival strategies in a stomach that is full of amino acid substrate. The amino acid antiporter, amino acid decarboxylase, and ClC chloride antiporter are all engaged in these systems, and each one plays a role in protecting against or adapting to the acidic environment. The ClC chloride antiporter, a member of the ClC channel family, eliminates negatively charged intracellular chloride ions to avoid inner membrane hyperpolarization as an electrical shunt of the acid resistance system. In this review, we will discuss the structure and function of the prokaryotic ClC chloride antiporter of amino acid-mediated acid resistance system.

• Fisheries and Aquatic Sciences
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• v.6 no.1
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• pp.27-33
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• 2003

A lactic acid bacterium showing antimicrobial activity against fish pathogen was isolated from gastrointestinal tract of flounder for the purpose of use as an aquaculture probiotics. From the analysis of morphological and physiological characteristics, the isolated strain was named as Lactococcus sp. HM58. Antimicrobial substance (AMS) from Lactococcus sp. HM58 showed strong growth inhibitory activity against Streptococcus sp., which is a fish pathogenic bacterium. AMS was presumed a proteinaceous compound with stability in heat and wide pH range from 2 to 10. It was started to produce in exponential growth phase and was not produced any more in stationary phase. It showed comparatively broad antimicrobial spectrum against most of gram positive bacteria used for this study. About $84\%$ of Lactococcus sp. HM58 was able to survive in the artificial gastric juice though it was low to the extent in the artificial bile juice. In the sensitivity test for various antibiotics, this strain was highly sensitive for doxycycline, erythromycin, amoxicillin clavu1anic acid and ampicillin.

• Journal of Life Science
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• v.32 no.5
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• pp.391-410
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• 2022

Human microbiota is a community of microorganisms, including bacteria, fungi, and viruses, that inhabit various locations of the body, such as the gut, oral, and skin. Along with the development of metabolomic analysis and next-generation sequencing techniques for 16S ribosomal RNA, it has become possible to analyze the population for subtypes of microbiota, and with these techniques, it has been demonstrated that bacterial microbiota are involved in the metabolic and immunological processes of the hosts. While specific bacteria of microbiota, called commensal bacteria, positively affect hosts by producing essential nutrients and protecting hosts against other pathogenic microorganisms, dysbiosis, an abnormal microbiota composition, disrupts homeostasis and thereby has a detrimental effect on the development and progression of various types of diseases. Recently, several studies have reported that oral and gut bacteria of microbiota are involved in the carcinogenesis of gastrointestinal tumors and the therapeutic effects of anticancer therapy, such as radiation, chemotherapy, targeted therapy, and immunotherapy. Studying the complex relationships (bacterial microbiota-cancer-immunity) and microbiota-related carcinogenic mechanisms can provide important clues for understanding cancer and developing new cancer treatments. This review provides a summary of current studies focused on how bacterial microbiota affect gastrointestinal cancer and anticancer therapy and discusses compelling possibilities for using microbiota as a combinatorial therapy to improve the therapeutic effects of existing anticancer treatments.

• Journal of Veterinary Science
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• v.25 no.5
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• pp.65.1-65.11
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• 2024

Importance: Recent developments in genetic analytical techniques have enabled the comprehensive analysis of gastrointestinal symbiotic bacteria as a screening tool for animal health conditions, especially the endangered gibbons at the National Wildlife Rescue Centre (NWRC). Objective: High-throughput sequencing based on 16S ribosomal RNA genes was used to determine the baseline gut bacterial composition and identify potential pathogenic bacteria among three endangered gibbons housed in the NWRC. Methods: Feces were collected from 14 individuals (Hylobates lar, n = 9; Hylobates agilis, n = 4; and Symphalangus syndactylus, n = 1) from March to November 2022. Amplicon sequencing were conducted by targeting V3-V4 region. Results: The fecal microbial community of the study gibbons was dominated by Bacteroidetes and Firmicutes (phylum level), Prevotellaceae and Lachnospiraceae/Muribaculaceae (family level), and Prevotella (and its subgroups) (genera level). This trend suggests that the microbial community composition of the study gibbons differed insignificantly from previously reported conspecific or closely related gibbon species. Conclusions and Relevance: This study showed no serious health problems that require immediate attention. However, relatively low alpha diversity and few potential bacteria related to gastrointestinal diseases and streptococcal infections were detected. Information on microbial composition is essential as a guideline to sustain a healthy gut condition of captive gibbons in NWRC, especially before releasing this primate back into the wild or semi-wild environment. Further enhanced husbandry environments in the NWRC are expected through continuous health monitoring and increase diversity of the gut microbiota through diet diversification.

• Journal of Dairy Science and Biotechnology
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• v.32 no.1
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• pp.1-6
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• 2014

Probiotics have been extensively studied for their beneficial effects on human health. In particular, Lactobacillus and Bifidobacterium strains have gained considerable attention as major groups of probiotic bacteria that improve gastrointestinal health. However, emerging evidence suggests that probiotics offer benefits beyond those observed in the gut recent studies suggest that probiotics and/or their components exert favorable effects on alcoholic liver disease (ALD) pathogenesis such as decreasing intestinal permeability, inhibiting pathogenic bacteria growth, increasing the activity of alcohol metabolism enzymes, modulating the adaptive immune system, and suppressing fatty acid synthesis genes. In this review, we discuss the results of in vivo and in vitro studies that have examined the use of probiotics to prevent ALD, primarily focusing on those that explore the cellular and molecular mechanisms underlying the activities of promising probiotic strains. The evidence presented in this review could help in screening for probiotic strains that have protective effects in ALD patients and in further elucidating the mechanisms of their actions.