• Fisheries and Aquatic Sciences
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• 제11권2호
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• pp.76-81
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• 2008

We isolated 1,916 strains of bacteria from gut and feces of abalone. The most active agarolytic bacterium, DAG-130, was identified from the gut of the abalone Haliotis gigantea. Of the bacteria harbored by both H. discus hannai and H. gigantea, 59% were agarolytic. There was no significant difference in the number of agarolytic bacteria isolated from abalone fed on the seaweeds Gelidium amansii, Laminaria japonica, or Undaria pinnatifida. Of the agarolytic bacteria, 72% were isolated from the guts of all sources tested while 43% came from the feces. The strain DAG-130 showed 100% identity with the bacterium Vibrio cyclotrophicus based on phylogenetic analysis of l6S rDNA. The bacterium produced monomers and oligomers from the agar substrate.

• Journal of Applied Biological Chemistry
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• 제65권4호
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• pp.447-451
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• 2022

Phytoestrogenic S-equol production in human gut exclusively depends on the biotransformation of daidzein to dihydrodaidzein (DHD). With a growing demand for the DHD enriched biomaterials, the commercial soybean hypocotyl extract (SHE) was chosen as a substrate for the microbial DHD production by human gut bacterium MRG-1, anaerobic DHD producer. To optimize the production of DHD, anaerobic fermentation conditions, including sterilization time, growth stage of inoculum, and growth media, were investigated. Maximum DHD production (1.2 g/L) was achieved after 48 h incubation when 1% (w/v) of SHE in the 20-min-sterilized Gifu Anaeboic Medium media was inoculated with OD₆₀₀ 0.3-0.4 of MRG-1. This is the first report that crude soy biomaterial, instead of pure compounds, such as daidzin and daidzein, is utilized for the production of the DHD enriched biomaterial.

• 한국응용곤충학회지
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• 제49권3호
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• pp.251-259
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• 2010

톱다리개미허리노린재(Riptortus clavatus)의 장내세균이 분리되었다. 형태학적 분석과 생화학적 분석을 통하여 세균이 Staphylococcus succinus와 가장 유사한 것으로 동정되었다. 16S rRNA 유전자의 염기서열은 이러한 동정 결과를 뒷받침했다. 페니실린G를 톱다리개미허리노린재 성충에게 경구투여 하였을 때 장내세균 밀도 감소와 치사 효과를 유발하였다. 동일한 방법으로 곤충병원세균(Xenorhabdus nematophila)의 세 가지 대사물질(benzylideneacetone, proline-tyrosine, and acetylated phenylalanine-glycine-valine)을 처리하였을 때, 톱다리개미허리노린재 장내세균의 밀도감소와 치사효과를 확인하였다. 이러한 결과는 톱다리개미허리노린재의 장내세균이 Staphylococcus sp.이며, 곤충병원세균 대사물질의 항균 활성이 장내세균과 궁극적으로 톱다리개미허리노린재의 생존에 영향을 미친다는 것을 제시하였다.

• Journal of Microbiology and Biotechnology
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• 제29권12호
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• pp.1904-1915
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• 2019

Resistant starch (RS) is metabolized by gut microbiota and involved in the production of short-chain fatty acids, which are related to a variety of physiological and health effects. Therefore, the availability of RS as a prebiotic is a topic of interest, and research on gut bacteria that can decompose RS is also important. The objectives in this study were 1) to isolate a human gut bacterium having strong degradation activity on non-gelatinized RS, 2) to characterize its RS-degrading characteristics, and 3) to investigate its probiotic effects, including a growth stimulation effect on other gut bacteria and an immunomodulatory effect. Bifidobacterium adolescentis P2P3 showing very strong RS granule utilization activity was isolated. It can attach to RS granules and form them into clusters. It also utilizes high-amylose corn starch granules up to 63.3%, and efficiently decomposes other various types of commercial RS without gelatinization. In a coculture experiment, Bacteroides thetaiotaomicron ATCC 29148, isolated from human feces, was able to grow using carbon sources generated from RS granules by B. adolescentis P2P3. In addition, B. adolescentis P2P3 demonstrated the ability to stimulate secretion of Th1 type cytokines from mouse macrophages in vitro that was not shown in other B. adolescentis. These results suggested that B. adolescentis P2P3 is a useful probiotic candidate, having immunomodulatory activity as well as the ability to feed other gut bacteria using RS as a prebiotic.

• 한국토양동물학회지
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• 제3권1호
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• pp.19-24
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• 1998

The importance of the gut microorganism in the termite, Reticulitermes Speratus kyushuenesis Morimoto, was estimated by feeding with several antibiotics. Antibiotics which killed the bacterium, but not the fungi (Ampicillin, Kanamycin, Erythromycin), or killed both the microorganismw (Cephaloridine, Tetracycline) reduced the life span of the termite from 245 days to about 15 days. On the other hand, some antibiotics, penicillin and pimaricin, did not greatly reduce the life span of the termite.

• Journal of Microbiology and Biotechnology
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• 제35권8호
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• pp.e2507001.1-e2507001.12
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• 2025

Akkermansia muciniphila, an intestinal bacterium, has garnered attention for its association with metabolic health and anti-inflammatory properties. However, its potential role in mitigating sarcopenia, particularly in the senescence-accelerated mouse-prone 8 (SAMP8) model, remains unexplored. In this study, we aimed to evaluate the potential effects of A. muciniphila supplementation on sarcopenia and its underlying mechanisms. Seven-month-old SAMP8 mice were administered A. muciniphila for 3 months. A. muciniphila supplementation enhanced grip strength and skeletal muscle mass, suppressed cellular senescence, improved the balance between protein degradation and synthesis, increased total ATP, and improved mitochondrial biogenesis. Analysis of the effects of A. muciniphila on gut microbiome using 16S rRNA sequencing showed that supplementation with A. muciniphila shifted the gut microbiota composition, alleviated gut dysbiosis, preserved gut barrier integrity, and reduced the protein expression of inflammatory cytokines in the intestine. Additionally, extracellular vesicles derived from A. muciniphila promoted myogenesis and suppressed dexamethasone-induced atrophy in C2C12 myoblasts. These findings suggest that supplementation with A. muciniphila mitigates sarcopenia by suppressing inflammation and improving the gut microenvironment, highlighting the potential of A. muciniphila as a new therapeutic candidate to treat sarcopenia.

• Journal of Microbiology and Biotechnology
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• 제33권12호
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• pp.1606-1614
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• 2023

Biochemical gut metabolism of dietary bioactive compounds is of great significance in elucidating health-related issues at the molecular level. In this study, a human gut bacterium cleaving C-C glycosidic bond was screened from puerarin conversion to daidzein, and a new, gram-positive C-glycoside-deglycosylating strain, Dorea sp. MRG-IFC3, was isolated from human fecal sample under anaerobic conditions. Though MRG-IFC3 biotransformed isoflavone C-glycoside, it could not metabolize other C-glycosides, such as vitexin, bergenin, and aloin. As evident from the production of the corresponding aglycons from various 7-O-glucosides, MRG-IFC3 strain also showed 7-O-glycoside cleavage activity; however, flavone 3-O-glucoside icariside II was not metabolized. In addition, for mechanism study, C-glycosyl bond cleavage of puerarin by MRG-IFC3 strain was performed in D₂O GAM medium. The complete deuterium enrichment on C-8 position of daidzein was confirmed by ¹H NMR spectroscopy, and the result clearly proved for the first time that daidzein is produced from puerarin. Two possible reaction intermediates, the quinoids and 8-dehydrodaidzein anion, were proposed for the production of daidzein-8d. These results will provide the basis for the mechanism study of stable C-glycosidic bond cleavage at the molecular level.

• Journal of Microbiology and Biotechnology
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• 제35권10호
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• pp.e2506004.1-e2506004.13
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• 2025

Probiotics offer a promising avenue for combating muscle atrophy, which is a debilitating condition associated with muscle disuse, aging, and disease. This study investigated the anti-atrophic potential of Limosilactobacillus reuteri ATG-F4, a human gut-derived bacterium, in a mouse model of staple-induced immobilization. ATG-F4 administration significantly preserved muscle mass and improved grip strength and endurance. Mechanistically, ATG-F4 activated mTOR signaling and promoted protein synthesis. Additionally, ATG-F4 downregulated MuRF1, a key atrophy factor. Furthermore, ATG-F4 administration significantly altered the composition of the gut microbiota, favoring the presence of the Muribaculaceae family and decreasing the abundance of Lachnospiraceae and Lactobacillaceae. Administration of ATG-F4 increased serum levels of the short-chain fatty acids (SCFAs) butyrate and acetate. SCFAs, which are produced by bacterial fermentation in the gut, possess anti-inflammatory and beneficial muscle properties and exert several effects on host metabolism and the immune system. Therefore, we suggest that the potential mechanism underlying the anti-atrophic effects of ATG-F4 on muscles involves the enhancement of muscle protein synthesis, suppression of protein degradation, and modulation of the gut-muscle axis. These findings highlight the potential of ATG-F4 as a prophylactic or therapeutic agent for the treatment of muscle atrophy.

• 한국미생물·생명공학회지
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• 제38권2호
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• pp.117-123
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• 2010

BT toxin is produced by a soil bacterium Bacillus thuringiensis and has long been used as a biological insecticide without any competition. Recently, Photorhabdus, a symbiotic bacterium from entomopathogenic nematodes, family Heterorhabditae, has been researched and discussed as alternatives to B. thuringiensis. Photorhabdus, which lives in the gut of entomopathogenic nematodes, is a highly virulent pathogen of a wide range of insect larvae. When an insect is infected by the nematodes, the bacteria are released into the cadaver, and produce a number of insecticidal toxins. The biological role of the different Photorhabdus toxins in the infection process is still unclear. Photorhabdus toxin complex (Tc) is highly secreted gut-active toxin and has been characterized as a potent three-component (A, B and C) insecticidal protein complex. These components are necessary for full oral activity against insect larvae. The Photorhabdus PirAB binary toxins exhibit a potent injectable activity for Galleria mellonella larvae, and have oral toxicity against mosquitoes and caterpillar pest Plutella xylostella. Other toxin, 'makes caterpillars floppy' (Mcf) showed injectable activity on caterpillars. Recombinant Mcf triggers apoptosis in both insect hemocytes and the midgut epithelium and carries a BH3 domain. In this review, the relationship between the Photorhabdus and the nematode is discussed and recent important insecticidal toxins from Photorhabdus are described.

• Journal of Microbiology and Biotechnology
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• 제34권6호
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• pp.1270-1275
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• 2024

Human gut bacterium Dorea sp. MRG-IFC3 is unique in that it is capable of metabolizing puerarin, an isoflavone C-glycoside, whereas it shows broad substrate glycosidase activity for the various flavonoid O-glycosides. To address the question on the substrate specificity, as well as biochemical characteristics, cell-free biotransformation of flavonoid glycosides was performed under various conditions. The results showed that there are two different enzyme systems responsible for the metabolism of flavonoid C-glycosides and O-glycosides in the MRG-IFC3 strain. The system responsible for the conversion of puerarin was inducible and comprised of two enzymes. One enzyme oxidizes puerarin to 3"-oxo-puerarin and the other enzyme converts 3"-oxo-puearin to daidzein. The second enzyme was only active toward 3"-oxo-puerarin. The activity of puerarin conversion to daidzein was enhanced in the presence of Mn²⁺ and NAD⁺. It was concluded that the puerarin C-deglycosylation by Dorea sp. MRG-IFC3 possibly adopts the same biochemical mechanism as the strain PUE, a species of Dorea longicatena.