• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.169-175
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• 2000

The filamentous soil bacterium Streptomyces coelicolor is known to produce four distinct antibiotics. The simultaneous global regulation for the biosynthesis of those four antibiotics was previously confirmed by absA and absB mutations that blocked all four antibiotics' biosynthesis without influencing their morphological differentiation. To study the complex regulatory cascade that controls the secondary metabolism in Streptomyces, a new abs-like mutation was characterized. namely absR, which is slightly leaky on a complete R2YE medium, yet tight on a minimal medium. A genetic analysis of the absR locus indicated that it is located at 10 o'clock on the genetic map, near the site of absA. A cloned copy of the absA gene that encoded bacterial two-component regulatory kinases did not restore antibiotic biosyntheis to the absR mutant. Accordingly, it is proposed that absR is another abs-type mutation which is less tight than the previously identified absA or absB mutations income medium conditions, and can be used to characterize another global regulatory gene for secondary metabolete formation in S. coelicolor.

• Journal of Microbiology
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• v.39 no.3
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• pp.213-218
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• 2001

The treatment of Patients with bacteraemia and septicemia requires accurate and rapid identification of the pathogen so that the physician can be guided regarding the selection of the proper antimicrobial therapy. The usual procedure is to withdraw an aliquot of the positive blood culture sample for gram staining and subculturing on the media for the growth and subsequent identification, and susceptibility determinations. It was noticed that during the process some microbiologists would sniff the effluent gases that are products of metabolism and in some cases guess the identity of the bacterium. That Prompted us to engage in systematic investigation of two gram positive and two gram negative bacteria using an electronic nose that had been proven successful in distinguishing the aroma of coffee beans from different sources. The investigation was successful in illustrating the efficacy of such a device in this clinical setting to distinguish Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis. A representative set of patterns obtained with this apparatus is displayed as well. A representative set of patterns obtained with this apparatus is displayed as well. No effort was made to determine an optimal set of sensors for some specific set of bacterial metabolism gaseous products.

• Archives of Pharmacal Research
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• v.21 no.1
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• pp.17-23
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• 1998

Flavonoid glycosides were metabolized to phenolic acids via aglycones by human intestinal microflora producing ${\alpha}$-rhamnosidase, exo-${\beta}$-glucosidase, endo- ${\beta}$-glucosidase and/or ${\beta}$-glucuronidase. Rutin, hesperidin, naringin and poncirin were transformed to their aglycones by the bacteria producing ${\alpha}$-rhamnosidase and ${\beta}$-glucosidase or endo- ${\beta}$-glucosidase, and baicatin, puerarin and daidzin were transformed to their aglycones by the bacteria producing ${\beta}$glucuronidase, C-glycosidase and ${\beta}$-glycosidase, respectively. Anti-platelet activity and cytotoxicity of the metabolites of flavonoid glycosides by human intestinal bacteria were more effective than those of the parental compounds. 3,4-Dihydroxyphenylacetic acid and 4-hydroxyl-phenylacetic acid were more effective than rutin and quercetin on anti-platelet aggregation activity. 2,4,6-Trihydroxybenzaidehyde, quercetin and ponciretin were more effective than rutin and ponciretin on the cytotoxicity for tumor cell lines. We insist that these flavonoid glycosides should be natural prodrugs.

• Journal of Ginseng Research
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• v.48 no.3
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• pp.253-265
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• 2024

Orally administered ginsenosides, the major active components of ginseng, have been shown to be biotransformed into a number of metabolites by gastric juice, digestive and bacterial enzymes in the gastrointestinal tract and also in the liver. Attention is brought to pharmacokinetic studies of ginseng that need further clarification to better understand the safety and possible active mechanism for clinical application. Experimental results demonstrated that ginsenoside metabolites play an important role in the pharmacokinetic properties such as drug metabolizing enzymes and drug transporters, thereby can be applied as a metabolic modulator. Very few are known on the possibility of the consistency of detected ginsenosides with real active metabolites if taken the recommended dose of ginseng, but they have been found to act on the pharmacokinetic key factors in any clinical trial, affecting oral bioavailability. Since ginseng is increasingly being taken in a manner more often associated with prescription medicines, ginseng and drug interactions have been also reviewed. Considering the extensive oral administration of ginseng, the aim of this review is to provide a comprehensive overview and perspectives of recent studies on the pharmacokinetic properties of ginsenosides such as deglycosylation, absorption, metabolizing enzymes and transporters, together with ginsenoside and drug interactions.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.9-19
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• 2011

The Bacillus subtilis pyrimidine biosynthetic (pyr) operon encodes all of the enzymes for the de novo biosynthesis of Uridine monophosphate (UMP) and additional cistrones encoding a uracil permease and the regulatory protein PyrR. The PyrR is a bifunctional protein with pyr mRNA-binding regulatory funtion and uracil phosphoribosyltransferase activity. To study the global regulation by the pyrR deletion, the proteome comparison between Bacillus subtilis DB104 and Bacillus subtilis DB104 ${\Delta}$pyrR in the minimal medium without pyrimidines was employed. Proteome analysis of the cytosolic proteins from both strains by 2D-gel electrophoresis showed the variations in levels of protein expression. On the silver stained 2D-gel with an isoelectric point (pI) between 4 and 10, about 1,300 spots were detected and 172 spots showed quantitative variations in which 42 high quantitatively variant proteins were identified. The results showed that production of the pyrimidine biosynthetic enzymes (PyrAA, PyrAB, PyrB, PyrC, PyrD, and PyrF) were significantly increased in B. subtilis DB104 ${\Delta}$pyrR. Besides, proteins associated carbohydrate metabolism, elongation protein synthesis, metabolism of cofactors and vitamins, motility, tRNA synthetase, catalase, ATP-binding protein, and cell division protein FtsZ were overproduced in the PyrR-deficient mutant. Based on analytic results, the PyrR might be involved a number of other metabolisms or various phenomena in the bacterial cell besides the pyrimidine biosynthesis.

• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.152-161
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• 2015

CodY is a highly conserved protein in low G+C gram-positive bacteria that regulates genes involved in sporulation and stationary-phase adaptation. Bacillus thuringiensis is a grampositive bacterium that forms spores and parasporal crystals during the stationary phase. To our knowledge, the regulatory mechanism of CodY in B. thuringiensis is unknown. To study the function of CodY protein in B. thuringiensis, BMB171codY^- was constructed in a BMB171 strain. A shuttle vector containing the ORF of cry1Ac10 was transformed into BMB171 and BMB171codY^-, named BMB171cry1Ac and BMB171codY^-cry1Ac, respectively. Some morphological and physiological changes of codY mutant BMB171codY^-cry1Ac were observed. A comparative proteomic analysis was conducted for both BMB171codY^-cry1Ac and BMB171cry1Ac through two-dimensional gel electrophoresis and MALDI-TOF-MS/MS analysis. The results showed that the proteins regulated by CodY are involved in microbial metabolism, including branched-chain amino acid metabolism, carbohydrate metabolism, fatty acid metabolism, and energy metabolism. Furthermore, we found CodY to be involved in sporulation, biosynthesis of poly-β-hydroxybutyrate, growth, genetic competence, and translation. According to the analysis of differentially expressed proteins, and physiological characterization of the codY mutant, we performed bacterial one-hybrid and electrophoretic mobility shift assay experiments and confirmed the direct regulation of genes by CodY, specifically those involved in metabolism of branched-chain amino acids, ribosomal recycling factor FRR, and the late competence protein ComER. Our data establish the foundation for in-depth study of the regulation of CodY in B. thuringiensis, and also offer a potential biocatalyst for functions of CodY in other bacteria.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.723-726
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• 2001

This study was performed to improve the yield of bacterial cellulose(BC) by UV and NTG mutagenesis of strain KJ-1 which produced largely BC. some mutants showed high BC productivity with twice elevation compared to that the wild strain KJ-1. A difference was found in production and bioconversion phase of synthesized organic acid, such as gluconic acid, 2-keto gluconic acid, and 5-keto gluconic acid between mutants and strain KJ-1 in the static culture. The organic acid produced in secondary metabolism phase, were more rapidly consumed in the culture with the mutants than that the parent strain after glucose in the broth was conversed to a limiting substrate. Therefore, we suggested the reason for increasing of BC production that the mutant strain consumed more efficiently synthesized acids as substrates than that of the parent strain.

• Animal Bioscience
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• v.34 no.9
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• pp.1466-1478
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• 2021

Objective: Ruminants are completely dependent on their microbiota for rumen fermentation, feed digestion, and consequently, their metabolism for productivity. This study aimed to evaluate the rumen bacteria of lactating yaks with different milk protein yields, using high-throughput sequencing technology, in order to understand the influence of these bacteria on milk production. Methods: Yaks with similar high milk protein yield (high milk yield and high milk protein content, HH; n = 12) and low milk protein yield (low milk yield and low milk protein content, LL; n = 12) were randomly selected from 57 mid-lactation yaks. Ruminal contents were collected using an oral stomach tube from the 24 yaks selected. High-throughput sequencing of bacterial 16S rRNA gene was used. Results: Ruminal ammonia N, total volatile fatty acids, acetate, propionate, and isobutyrate concentrations were found to be higher in HH than LL yaks. Community richness (Chao 1 index) and diversity indices (Shannon index) of rumen microbiota were higher in LL than HH yaks. Relative abundances of the Bacteroidetes and Tenericutes phyla in the rumen fluid were significantly increased in HH than LL yaks, but significantly decreased for Firmicutes. Relative abundances of the Succiniclasticum, Butyrivibrio 2, Prevotella 1, and Prevotellaceae UCG-001 genera in the rumen fluid of HH yaks was significantly increased, but significantly decreased for Christensenellaceae R-7 group and Coprococcus 1. Principal coordinates analysis on unweighted UniFrac distances revealed that the bacterial community structure of rumen differed between yaks with high and low milk protein yields. Furthermore, rumen microbiota were functionally enriched in relation to transporters, ABC transporters, ribosome, and urine metabolism, and also significantly altered in HH and LL yaks. Conclusion: We observed significant differences in the composition, diversity, fermentation product concentrations, and function of ruminal microorganisms between yaks with high and low milk protein yields, suggesting the potential influence of rumen microbiota on milk protein yield in yaks. A deeper understanding of this process may allow future modulation of the rumen microbiome for improved agricultural yield through bacterial community design.

• Journal of Ginseng Research
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• v.45 no.2
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• pp.334-343
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• 2021

Background: Gut microbiota mainly function in the biotransformation of primary ginsenosides into bioactive metabolites. Herein, we investigated the effects of three prebiotic fibers by targeting gut microbiota on the metabolism of ginsenoside Rb1 in vivo. Methods: Sprague Dawley rats were administered with ginsenoside Rb1 after a two-week prebiotic intervention of fructooligosaccharide, galactooligosaccharide, and fibersol-2, respectively. Pharmacokinetic analysis of ginsenoside Rb1 and its metabolites was performed, whilst the microbial composition and metabolic function of gut microbiota were examined by 16S rRNA gene amplicon and metagenomic shotgun sequencing. Results: The results showed that peak plasma concentration and area under concentration time curve of ginsenoside Rb1 and its intermediate metabolites, ginsenoside Rd, F2, and compound K (CK), in the prebiotic intervention groups were increased at various degrees compared with those in the control group. Gut microbiota dramatically responded to the prebiotic treatment at both taxonomical and functional levels. The abundance of Prevotella, which possesses potential function to hydrolyze ginsenoside Rb1 into CK, was significantly elevated in the three prebiotic groups (P < 0.05). The gut metagenomic analysis also revealed the functional gene enrichment for terpenoid/polyketide metabolism, glycolysis, gluconeogenesis, propanoate metabolism, etc. Conclusion: These findings imply that prebiotics may selectively promote the proliferation of certain bacterial stains with glycoside hydrolysis capacity, thereby, subsequently improving the biotransformation and bioavailability of primary ginsenosides in vivo.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.67-73
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• 2008

The potential of the exopolysaccharide (EPS) from a Serratia sp. strain Gsm01 as an antiviral agent against a yellow strain of Cucumber mosaic virus (CMV-Y) was evaluated in tobacco plants (Nicotiana tabacum cv. Xanthi-nc). The spray treatment of plants using an EPS preparation, 72h before CMV-Y inoculation, protected them against symptom appearance. Fifteen days after challenge inoculation with CMV-Y, 33.33% of plants showed mosaic symptoms in EPS-treated plants compared with 100% in the control plants. The EPS-treated plants, which showed mosaic symptoms, appeared three days later than the controls. The enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR) analyses of the leaves of the protected plants revealed that the EPS treatment affected virus accumulation in those plants. Analysis of phenylalanine ammonia lyase, peroxidase, and phenols in protected plants revealed enhanced accumulation of these substances. The pathogenesis-related (PR) genes expression represented by PR-lb was increased in EPS-treated plants. This is the first report of a systemic induction of protection triggered by EPS produced by Serratia sp. against CMV-Y.