• BMB Reports
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• v.44 no.9
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• pp.590-594
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• 2011

The production of antileukemic enzyme methionine ${\gamma}$-lyase (MGL) in distinctly related bacteria, Citrobacter freundii and in their recombinants expressing the Vitresocilla hemoglobin (VHb) has been studied. This study concerns the potential of Citrobacter freundii expressing the Vitreoscilla hemoglobin gene (vgb) for the methionine ${\gamma}$- liyase production. Methionine ${\gamma}$- liyase production by Citrobacter freundii and its $vgb^-$ and $vgb^+$ bearing recombinant strain was studied in shake-flasks under 200 rpm agitation, culture medium and $30^{\circ}C$ in a time-course manner. The $vgb^+$ and especially the carbon type had a dramatic effect on methionine ${\gamma}$- liyase production. The $vgb^+$ strain of C. freundii had about 2-fold and 3.1-fold higher levels of MGL than the host and $vgb^-$ strain, respectively.

• Korean Journal of Microbiology
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• v.54 no.1
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• pp.79-80
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• 2018

Citrobacter freundii is a facultative anaerobic and a Gram-negative bacterium of Enterobacteriaceae family, and is an opportunistic pathogen. Bacteriophages infecting C. freundii can be an effective treatment for C. freundii infections. Here, the complete genomic sequence is announced for a lytic bacteriophage CF1 infecting C. freundii isolates.

• Journal of Veterinary Clinics
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• v.26 no.2
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• pp.150-154
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• 2009

In this paper, we described a case of mass mortality of doctor fish from a private fish hatchery farm in Korea with a history of abnormal swimming behavior, diffuse bleeding on the skin and fins and sudden death caused by fish pathogenic bacteria, Citrobacter freundii. Twelve moribund fish fingerling samples were submitted to College of Veterinary Medicine, Seoul National University in October 2008 for diagnostic examination. Diagnostic results showed that the morphological and biochemical properties of the bacteria isolated from the moribund fish were C. freundii. The remaining diseased fish from the hatchery farm were given treatment based on our recommendation and successfully recovered.

• Journal of the Korean Chemical Society
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• v.32 no.4
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• pp.333-341
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• 1988

The bio-electrode for cytosine has been constructed by immobilizing Proteus mirabilis and Citrobacter freundii on an ammonia gas-sensor. Bacteria containing cytosine deaminase convert one molecule of cytosine into one molecule of ammonia. The Proteus mirabilis bacterial electrode showed linear response to cytosine concentration in the $1.0{\times}10^{-3}\;-\;5.0{\times}10^{-2}$M with a slope of 45-48 mV/decade in 0.2 M phospbate buffer solution at pH 8.4. The Citrobacter freundii bacterial electrode showed linear response to cytosine concentration in the $7.0{\times}10^{-5}\;-\;7.0{\times}10^{-3}$M with a slope of 48 mV/decade in 0.05M phosphate buffer solution at pH 7.6. These electrode were investigated for the effects of pH, temperature, buffer solutions, amounts of bacteria, interferences, inorganic salts and lifetime.

• Archives of Pharmacal Research
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• v.24 no.4
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• pp.316-322
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• 2001

Arylsulfate sulfotransferase (ASST) transfers a sulfate group from a phenolic sulfate ester to a phenolic acceptor substrate. In the present study, the gene encoding ASST was cloned from a genomic library copy of Citrobacter freundii, subcloned into the vector pGEM3Zf(-) and sequenced. Sequencing revealed two contiguous open reading frames (ORF1 and ORF2) on the same strand and based on amino acid sequence homologyl they were designated as astA and dsbA, respectively. The amino acid sequence of astA deduced from C. freundii was highly similar to that of the Salmonella typhimurium, Enterobacter amnigenus, Klebsiella, Pseudomonas putida, and Campylobacter jejuni, encoded by the astA genes. However, the ASST activity assay revealed different acceptor specificities. Using p-nitrophenyl sulfate (PNS) as a donor substrate, $\alpha$-naphthol was found to be the best acceptor substrate, followed by phenol, resorcinol, p-acetaminophen, tyramine and tyrosine.

• Journal of the Korean Chemical Society
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• v.34 no.5
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• pp.424-429
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• 1990

A bio-sensor for the determination of glucose has been constructed by immobilizing the Citrobacter freundii or its organelle on carbon dioxide gas-sensor. The bacterial sensor was better than organelle in response, but the latter showed a shorter response time. The bacterial sensor gave linearity between 7.0 ${\times}\;10^{-4}$ and 1.0 ${\times}\;10^{-2}$ M glucose with a slope of 42.2 mV/decade in pH 7.0, 0.2 M tris-HCl buffer at 30$^{\circ}C$. The selectivity of this sensor was very high for glucose. Employing for the determination of glucose in serum, the sensor showed a good agreement with a routine analyzer.

• The Korean Journal of Food And Nutrition
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• v.21 no.1
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• pp.15-21
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• 2008

In this study, the minimum inhibition concentration(MIC), growth inhibition activity, and colony forming inhibitory activity of water soluble propolis against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Streptococcus mutans, Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae and Salmonella enteritidis were tested. The MICs of the water soluble propolis against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Streptococcus mutans, Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, and Salmonella enteritidis were 312.5 ppm, below 156.3 ppm, 625 ppm, 10,000 ppm, above 10,000 ppm, 10,000 ppm, above 10,000 ppm, above 10,000 ppm, 10,000 ppm, and above 10,000 ppm, respectively. The growth inhibition concentrations against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Streptococcus mutans, Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, and Klebsiella pneumoniae were 156.3 ppm, below 156.3 ppm, 625 ppm, 5,000 ppm, 10,000 ppm, 10,000 ppm, 10,000 ppm, 10,000 ppm, and 5,000 ppm, respectively. However, 10,000 ppm did not inhibit the growth of Salmonella enteritidis. Finally, the colony forming inhibitory activities against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Streptococcus mutans, Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, and Salmonella enteritidis were 98.0%, 99.8%, 69.8%, 98.1%, 62.0%, 63.1%, 79.5%, 61.9%, 79.6%, and 0.0%, respectively.

• Journal of fish pathology
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• v.35 no.1
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• pp.77-92
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• 2022

Aquaculture development is based on the ideas of increasing production while reducing economic losses. Bacterial diseases are the leading source of fish cases. Citrobacter freundii has been linked to septicemia and mortality all over the world. In the current study, the cause of mortality in O. niloticus was C. freundii MW279218. External hemorrhages were seen on the affected fish, as well as paleness in the liver and kidney congestion. C. freundii MW279218 had a median lethal dosage of 1.5×10⁵ CFU/mL. Zinc oxide and zinc oxide nanoparticles (ZnO-NPs) were tested for their biocidal effectiveness against C. freundii MW279218. The lethal effect of ZnO-NPs for C. freundii MW279218 was 100% when compared to zinc oxide compound, and the inhibition zone width was 2.31.1mm at the highest tested concentrations (70 mg/L) compared to the lowest (35 and 45 mg/L, respectively). Fish were fed three different diets for 28 days: diet 1 (no additives), diet 2 (100 mg of ZnO-NPs/kg of feed), and diet 3 (200 mg of ZnO-NPs/kg of feed). Organs were also collected for histopathology 96 hours after injection (P<0.05). In the groups given 200 mg of ZnO-NPs, there was 10% mortality and 80% RPS. The group fed 100 mg of ZnO-NPs/kg, on the other hand, had 20% mortality and 60% RPS, compared to 50% mortality in the control positive group. Histopathological examinations demonstrated significant alterations in the control positive group and mild lesions in the hepatopancreas of the groups administered 100 mg ZnO-NPs/kg of feed. The groups fed 200 mg of ZnO-NPs/kg diet, on the other hand, showed no histological alterations. ZnO-NPs were found to be effective in the up regulation of both IL-10 and complement 5 immune-related genes.

• Journal of Microbiology and Biotechnology
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• v.32 no.2
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• pp.176-186
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• 2022

Continued fenvalerate use has caused serious environmental pollution and requires large-scale remediation. Dibutyl phthalate (DBP) was discovered in fenvalerate metabolites degraded by Citrobacter freundii CD-9. Coculturing is an effective method for bioremediation, but few studies have analyzed the degradation pathways and potential mechanisms of cocultures. Here, a DBP-degrading strain (BDBP 071) was isolated from soil contaminated with pyrethroid pesticides (PPs) and identified as Stenotrophomonas acidaminiphila. The optimum conditions for DBP degradation were determined by response surface methodology (RSM) analysis to be 30.9 mg/l DBP concentration, pH 7.5, at a culture temperature of 37.2℃. Under the optimized conditions, approximately 88% of DBP was degraded within 48 h and five metabolites were detected. Coculturing C. freundii CD-9 and S. acidaminiphila BDBP 071 promoted fenvalerate degradation. When CD-9 was cultured for 16 h before adding BDBP 071, the strain inoculation ratio was 5:5 (v/v), fenvalerate concentration was 75.0 mg/l, fenvalerate was degraded to 84.37 ± 1.25%, and DBP level was reduced by 5.21 mg/l. In addition, 12 fenvalerate metabolites were identified and a pathway for fenvalerate degradation by the cocultured strains was proposed. These results provide theoretical data for further exploration of the mechanisms used by this coculture system to degrade fenvalerate and DBP, and also offer a promising method for effective bioremediation of PPs and their related metabolites in polluted environments.

• Proceedings of the Korean Society of Life Science Conference
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• 2000.09a
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• pp.58-58
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• 2000