• Journal of Microbiology and Biotechnology
• /
• v.18 no.3
• /
• pp.490-496
• /
• 2008

Symbiobacterium toebii is a commensal symbiotic thermophile that cannot grow without support from a partner bacterium. We investigated the properties of Symbiobacterium growth-supporting factors (SGSFs) produced by the partner bacterium Geobacillus toebii. SGSFs occurred in both the cell-free extract (CFE) and culture supernatant of G. toebii and might comprise multifarious materials because of their different biological properties. The heavy SGSF contained in the cytosolic component exhibited heat- and proteinase-sensitive proteinaceous properties and had a molecular mass of >50 kDa. In contrast, the light SGSF contained in the extracellular component exhibited heat-stable, proteinase-resistant, nonprotein properties and had a molecular mass of <10 kDa. Under morphological examination using light microscopy, S. toebii cultured with the culture supernatant of G. toebii was filamentous, whereas S. toebii cultured with the CFE of G. toebii was rod-shaped. These results strongly suggest that the SGSFs produced by G. toebii comprise two or more types that differ in their growth-supporting mechanisms, although all support the growth of S. toebii. Upon the examination of the distribution of SGSFs in other bacteria, both cytosolic and extracellular components of Geobacillus kaustophilus, Escherichia coli, and Bacillus subtilis had detectable growth-supporting effects for S. toebii, indicating that common SGSF materials are widely present in various bacterial strains.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.1
• /
• pp.59-64
• /
• 2018

Listeria monocytogenes can asymptomatically inhabit the human intestine as a commensal bacterium. However, the mechanism by which L. monocytogenes is able to inhabit the intestine without pathogenic symptoms remains unclear. We compared the invasion efficiency of L. monocytogenes strains with the 268- and 385-bp-long actA gene. Clinical strains SMFM-CI-3 and SMFM-CI-6 with 268-bp actA isolated from patients with listeriosis, and strains SMFM-SI-1 and SMFM-SI-2 with the 385-bp gene isolated from carcasses, were used for inoculum preparation. The invasion efficiency of these strains was evaluated using Caco-2 cells (intestinal epithelial cell line), prepared as normal and healthy cells with tightened tight junctions and senescent cells with loose tight junctions that were loosened by adriamycin treatment. The invasion efficiency of L. monocytogenes strains with the 268-bp-long actA gene was 1.1-2.6-times lower than that of the strains with the 385-bp-long gene in normal and healthy cells. However, the invasion efficiency of both types of strains did not differ in senescent cells. Thus, L. monocytogenes strains with the 268-bp-long actA gene can inhabit the intestine asymptomatically as a commensal bacterium, but they may invade the intestinal epithelial cells and cause listeriosis in senescent cells.

• Asian-Australasian Journal of Animal Sciences
• /
• v.14 no.3
• /
• pp.414-422
• /
• 2001

Antibiotic resistance in human pathogens is a major public health issue. Some of the resistance problem can be attributed to the transfer of resistant bacteria from animals to people and the transfer of resistance genes from animal pathogens and commensal bacteria to human pathogens. Control measures include improvements in food hygiene to reduce the spread of zoonotic bacteria to people via the food chain. However, to specifically address the issue, the medical profession must control misuse and overuse of antibiotics in hospitals and community practice. In addition, the livestock industries and their advisors must reduce and refine the use of antibiotics in animal production and replace antibiotics with alternative disease control measures as much as possible.

• BMB Reports
• /
• v.45 no.8
• /
• pp.433-441
• /
• 2012

Human milk, which nourishes the early infants, is a source of bioactive components for the infant growth, development and commensal formulation as well. Human milk oligosaccharide is a group of complex and diverse glycans that is apparently not absorbed in human gastrointestinal tract. Although most mammalian milk contains oligosaccharides, oligosaccharides in human milk exhibit unique features in terms of their types, amounts, sizes, and functionalities. In addition to the prevention of infectious bacteria and the development of early immune system, human milk oligosaccharides are able to facilitate the healthy intestinal microbiota. Bifidobacterial intestinal microbiota appears to be established by the unilateral interaction between milk oligosaccharides, human intestinal activity and commensals. Digestibility, membrane transportation and catabolic activity by bacteria and intestinal epithelial cells, all of which are linked to the structural of human milk oligosaccharides, are crucial in determining intestinal microbiota.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.11 no.sup2
• /
• pp.59-66
• /
• 2008

Genome-wide association studies using large case-control samples and several hundred thousand genetic markers efficiently and powerfully assay common genetic variations. The application of these studies to inflammatory bowel disease has led to the identification of susceptibility genes and affirmed the importance of innate and adaptive immunity in the pathogenesis of disease. Efforts directed towards the identification of environmental factors have implicated commensal bacteria as determinants of dysregulated immunity and inflammatory bowel disease. Host genetic polymorphisms most likely interact with functional bacterial changes to stimulate aggressive immune responses that lead to chronic tissue injury.

• Pediatric Infection and Vaccine
• /
• v.26 no.3
• /
• pp.129-139
• /
• 2019

The human respiratory tract hosts both pathogenic and commensal bacteria. The development of well-conserved 16S rRNA sequencing and culture-independent techniques has enabled many achievements in the study of the human microbiome. Microbial composition of the respiratory tract in early childhood has been shown to correlate to respiratory health in later stages of life. This review highlights current understandings of respiratory microbiota development in healthy children, examples of microbial interactions, impacts on the host immune system, and the relationship between respiratory tract microbiome and respiratory health.

• Proceedings of the Korean Society of Veterinary Pathology Conference
• /
• 2003.10a
• /
• pp.39-39
• /
• 2003

Balantidiasis is an infectious disease worldwide which is produced by a protozoan Balantidium coli. This single-celled organism is characterized by their large size ranging from 50 $\mu\textrm{m}$ to more than 500 $\mu\textrm{m}$ [1] which indicated by the presence of cilia on its cell surface. The parasite occurs in the lumen of cecum and colon of swine, humans and nonhuman primates as commensal, but can turn opportunist and invade injury tissues by other diseases [2]. It is difficult to diagnose the disease clinically since they are asymptomatic [3]; and can be complicated with other disease or parasitism. Here we report the incidental findings of Balantidiasis in the lymphatic ducts of gastric lymph node of Barbary sheep (Ammotragus lervia). (omitted)

• IMMUNE NETWORK
• /
• v.15 no.1
• /
• pp.1-8
• /
• 2015

Innate immune cells survey antigenic materials beneath our body surfaces and provide a front-line response to internal and external danger signals. Dendritic cells (DCs), a subset of innate immune cells, are critical sentinels that perform multiple roles in immune responses, from acting as principal modulators to priming an adaptive immune response through antigen-specific signaling. In the gut, DCs meet exogenous, non-harmful food antigens as well as vast commensal microbes under steady-state conditions. In other instances, they must combat pathogenic microbes to prevent infections. In this review, we focus on the function of intestinal DCs in maintaining intestinal immune homeostasis. Specifically, we describe how intestinal DCs affect IgA production from B cells and influence the generation of unique subsets of T cell.

• Korean Journal of Veterinary Research
• /
• v.59 no.3
• /
• pp.157-160
• /
• 2019

The production of rmtB-encoded 16S rRNA methylases has emerged as a novel mechanism promoting high-level resistance toward aminoglycosides in Gram-negative bacteria. Between 2015 and 2017, 636 distinct commensal Escherichia (E.) coli isolates were collected from different farms in South Korea to determine the prevalence and molecular characteristics of rmtB. The positive rates of rmtB between all the isolates and amikacin-resistant isolates were 1.1 and 100%, respectively. High-level aminoglycoside resistance could be transferred by conjugation from rmtB-positive donors to higher amikacin-resistance efficacies. This is the first report of 16S rRNA methylase-encoding genes in E. coli isolated from food-producing animals in Korea.

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