• Journal of Yeungnam Medical Science
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• v.9 no.2
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• pp.248-255
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• 1992

Eight bacterial strains were examined whether they have phoP/phoQ genes which were known to be involved in the intracellular survival of Salmonella typhimurium. The phoP/phoQ operon were known to sense the stimuli of the genes involved in the adaptation of the environment. Using 514-basepairs EcoRV DNA fragment of phoP region of Salmonella typhimurium as a probe, dot blot hybridization were performed. Chromosomal DNAs of Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marscescens, Enterobacter cloacae, Salmonella typhimurium, Escherichia coli, Shigella dysenteriae, and Listeria monocytogenes were examined by DNA hybridization assay. Against our expectation, intracellular pathogen, L. monocytogenes, did not have similar DNA sequences to phoP/phoQ of S. typhimurium, while E. coli, S. dysenteriae, and E. cloacae showed the positive signal even though they were not intracellular pathogens. This result suggested that the phoP/PhoQ operon was absent in intracellular pathogenic bacterias other than S. typhimurium. Rather it was found in phylogenetically closer bacterias to S. typhimurium, which were not able to survive in intracellular environment. Some different mechanism, which is not dependent on phoP/PhoQ operon, could be involved in the intracelluar survival of L. monocytogenes.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.4
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• pp.619-622
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• 1993

Rumen bacterial amino acids in sheep on urea diet were monitored to assess a possible change in amino acid synthesis as a long term response to high rumen ammonia environment. A sheep was fed a semipurified diet with soybean meal, followed by a diet with urea as a main nitrogen source. Mixed rumen bacteria were harvested from ruminal fluid taken 3 h after feeding (twice in soybean meal feeding and 6 times in urea feeding) and fractionated as cell wall, proteins and protein-free cell supernatant of monitor amino acids in each fraction. Ruminal ammonia concentration at the sampling ranged from 5.7 to 39.5 mgN/dl. Cell wall and protein fractions of mixed rumen bacteria were stable in their amino acid composition regardless of nitrogen sources of diet and the feeding duration. However, protein-free cell supernatant fraction showed a higher alanine proportion with urea feeding (18.6 and 28.2 molar % of alanine for samples from sheep fed soybean meal and urea, respectively) and its duration (20.6 and 32.9 molar % for samples from sheep on urea diet for 1 and 65 days, respectively). Total free amino acid level of bacteria was depressed in the initial period of urea feeding but restored on 65th day of the feeding. These results suggest that an alanine synthesizing system may develop in rumen bacteria as urea feeding becomes longer.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.349-354
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• 2006

Furaneol, a key aroma compound found in strawberry, pineapple, and processed foodstuffs, has been known to possess various biological activities on animal models. In this study, the antimicrobial effects of furaneol against human pathogenic microorganisms were investigated. The results indicated that furaneol displayed a broad spectrum of antimicrobial activities against Gram-positive and Gram-negative bacteria and fungi without hemolytic activity on human erythrocyte cells. To confirm the antifungal activity of furaneol, we examined the accumulation of intracellular trehalose as a stress response marker on toxic agents and its effect on dimorphic transition of Candida albicans. The results demonstrated that furaneol induced significant accumulation of intracellular trehalose and exerted its antifungal effect by disrupting serum-induced mycelial forms. These results suggest that furaneol could be a therapeutic agent having a broad spectrum of antimicrobial activity on human pathogenic microorganisms.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1330-1336
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• 2005

Polyhydroxyalkanoic acid (PHA) inclusion bodies were analyzed in situ by $^{13}C$-nuclear magnetic resonance ($^{13}C$-NMR) spectroscopy. The PHA inclusion bodies studied were composed of poly(3-hydroxybutyrate) or poly(3hydroxybutyrate-co-4-hydroxybutyrate), which was accumulated in Hydrogenophaga pseudoflava, and medium-chain-length PHA (MCL-PHA), which was accumulated in Pseudomonas fluorescens BM07 from octanoic acid or 11-phenoxyundecanoic acid (11-POU). The quantification of the $^{13}C$-NMR signals was conducted against a standard compound, sodium 2,2-dimethyl-2-silapentane-5-sulfonate (DSS). The chemical shift values for the in vivo NMR spectral peaks agreed well with those for the corresponding purified PHA polymers. The intracellular degradation of the PHA inclusions by intracellular PHA depolymerase(s) was monitored by in vivo NMR spectroscopy and analyzed in terms of first-order reaction kinetics. The H. pseudoflava cells were washed for the degradation experiment, transferred to a degradation medium without a carbon source, but containing 1.0 g/l ammonium sulfate, and cultivated at $35^{\circ}C$ for 72 h. The in vivo NMR spectra were obtained at $70^{\circ}C$ for the short-chain-length PHA cells whereas the spectra for the aliphatic and aromatic MCL-PHA cells were obtained at $50^{\circ}C\;and\;80^{\circ}C$, respectively. For the H. pseudoflava cells, the in vivo NMR kinetics analysis of the PHA degradation resulted in a first-order degradation rate constant of 0.075/h ($r^{2}$=0.94) for the initial 24 h of degradation, which was close to the 0.050/h determined when using a gas chromatographic analysis of chloroform extracts of sulfuric acid/methanol reaction mixtures of dried whole cells. Accordingly, it is suggested that in vivo $^{13}C$-NMR spectroscopy is an important tool for studying intracellular PHA degradation in terms of kinetics.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.169-175
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• 2011

The ${\beta}$-xylosidase (EC 3.2.1.37) production capabilities of lactic acid bacteria in the genus Leuconostoc, isolated from a variety of kimchi (fermented vegetables), were examined. The intracellular levels of ${\beta}$-xylosidase were similar to the extracellular levels, when most Leuconostoc lactic acid bacteria were grown in a medium containing xylose as the carbon source. Intracellular ${\beta}$-xylosidase with a maximum activity of $1.2{\pm}0.1units/mL$ (mean${\pm}$standard error) was obtained from Leuconostoc lactis KCTC 13344, which was isolated from fermented Chinese cabbage. The optimum reaction conditions for Leu. lactis KCTC 13344 ${\beta}$-xylosidase activity were pH 6.0 and $30^{\circ}C$, and the addition of most divalent cations, except zinc, to the reaction mixture resulted in a slight increase in enzyme activity. Compared with a media containing other carbon sources, the ${\beta}$-xylosidase activity was 5 times higher when Leu. lactis KCTC 13344 was grown in a medium containing xylose as carbon source. Zymographic analysis indicated that the synthesis of Leu. lactis KCTC 13344 ${\beta}$-xylosidase (approximate size, 64 kDa) is induced by xylose. A maximum intracellular ${\beta}$-xylosidase activity of $7.1{\pm}0.3units/mL$ was obtained in a batch cultivation in an MRS medium containing 30 g/L xylose.

• Applied Microscopy
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• v.48 no.4
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• pp.96-101
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• 2018

The release of nanoscale membrane-bound vesicles is common in all three domains of life. These vesicles are involved in a variety of biological processes such as cell-to-cell communication, horizontal gene transfer, and substrate transport. Prokaryotes including bacteria and archaea release membrane vesicles (MVs) (20 to 400 nm in diameter) into their extracellular milieu. In spite of structural differences in cell envelope, both Gram-positive and negative bacteria produce MVs that contain the cell membrane of each bacterial species. Archaeal MVs characteristically show surface-layer encircling the vesicles. Filamentous fungi and yeasts as eukaryotic microbes produce bilayered exosomes that have varying electron density. Microbes also form intracellular vesicles and minicells that are similar to MVs and exosomes in shape. Electron and fluorescence microscopy could reveal the presence of DNA in MVs and exosomes. Given the biogenesis of extracellular vesicles from the donor cell, in situ high-resolution microscopy can provide insights on the structural mechanisms underlying the formation and release of microbial extracellular vesicles.

• Journal of Periodontal and Implant Science
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• v.38 no.4
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• pp.691-698
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• 2008

Purpose: Periodontal pathogens can invade the host tissue. Morphologic studies have revealed bacteria within the pocket epithelium, gingival connective tissues, alveolar bone, and oral epithelium. The objective of this study was to visualize and evaluate presence of Porphyromonas gingivalis and Tannerella forsythia in crevicular epithelial cells of periodontally healthy subjects and chronic periodontitis patients. Materials and Methods: A total of 666 crevicular epithelial cells in the samples obtained from 27 chronic periodontitis patients and 9 healthy volunteers were examined. Specific probes for P. gingivalis and T. forsythia and a universal probe for detection of all eubacteria targeting 168 rRNA for fluorescence in situ hybridization was used in conjunction with confocal laser scanning microscopy. Results: 98.99% of sulcular epithelial cells from healthy volunteers and 84.40% of pocket epithelial cells from periodontitis patients were found to harbor bacteria. P. gingivalis and T. forsythia were discovered more often in crevicular epithelial cells from periodontitis patients. Conclusion: P. gingivalis and T. forsythia can invade crevicular epithelial cells and intracellular bacteria may act as a source of bacteria for persistent infection.

• Microbiology and Biotechnology Letters
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• v.23 no.4
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• pp.373-377
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• 1995

We investigated the survival, $\beta$-galactosidase activity and cellular permeability of lactic acid bacteria such as Lactobacillus acidophilus ATCC 4356, Lactobacillus casei subsp. casei IFO 3533, Streptococcus thermophilus KCTC 2185, Lactobacillus delbrueckii subsp. lactis ATCC 4797, and Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 in anaerobic condition of pH 1.5-3.5 range. Numbers of all tested viable cells did not decrease at pH 3.5, but decreased rapidly at pH 1.5 and pH 2.5 during 2 hour incubation at modified EG medium. Immediately after 2 hour incubation, the decrease in population at pH 1.5 and pH 2.5 was about 6-8 and 5-7 log cycles/ml, respectively. Lactobacillus acidophilus ATCC 4356 showed the higest survival of all tested bacteria. The $\beta$-galactosidase activity from Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 and Streptococcus thermophilus KCTC 2185 decreased rapidly at pH 1.5 and 2.5, but there was a little decrease at pH 3.5. The cellular permeability that was measured by the leakage of intracellular materials increased with decrease of pH. These results suggest that the ingested lactic acid bacteria may be destroyed in contact with low pH of gastric acid.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.280-286
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• 2021

This study was performed to screen the antimicrobial activities and proteolytic enzyme stability of the acidified extract of the Blue mussel Mytilus edulis. The acidified extract showed potent antimicrobial activities against Gram-positive bacteria, Bacillus subtilis, and Gram-negative bacteria, Escherichia coli D31, but had no activity against Candida albicans. Treatment of extract with trypsin completely abolished all or significant antibacterial activity against the tested bacteria, but slightly decreased antimicrobial activity against B. subtilis, and treatment of extract with chymotrypsin retained almost antibacterial activity against the tested bacteria except for E. coli D31. To confirm the additional enzyme stability of the extract, antimicrobial activity of the extract was tested after treated with several enzymes. Enzymes treated extract showed potent antimicrobial activity against B. subtilis and its activity was also retained for 5 h after trypsin treatments. Non-proteinaceous materials in the acidified extract also showed strong DNA-binding ability but did not show bacterial membrane permeabilizing ability. All our results indicate that mussel extract might contain the proteinaceous or non-proteinaceous antibacterial materials target not bacterial membrane but intracellular components. These results could be used to develop mussel extract as an additive for the improvement of stability or antimicrobial activity of antibiotics against specific bacteria.

• Microbiology and Biotechnology Letters
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• v.12 no.4
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• pp.305-309
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• 1984

A selective medium which allows growth of only cellulolytic bacteria was developed. The medium composed of 0.5% carboxymethylcellulose (CMC), 0.005% yeast extract, minerals and agar. Colony formation on this medium indicates overall activities of cellulose utilization. A subsequent test with Congo Red dye could distinguish extracellular cellulolysis from intracellular type.