• Clean Technology
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• v.24 no.4
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• pp.293-300
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• 2018

Sulfamethoxazole (SMX) is sulfaamide-based synthetic antibiotics, which are widely prescribed pharmaceutical compound to treat bacterial infections in both human and animals. Most of them are not completely decomposed as refractory substances. The environmental impact of pharmaceuticals as emerging contaminants has generated severe concerns. In this study, catalytic wet peroxide oxidation (CWPO) of SMX was carried out with $Cu/Al_2O_3$ catalyst and investigated the optimum reaction conditions of temperature, dosage of catalyst and concentration of $H_2O_2$ to completely decompose the SMX. It was observed that SMX was completely decomposed within 20 min using 0.79 mM $H_2O_2$ and 6 g $Cu/Al_2O_3$ catalyst at 1 atm and $40^{\circ}C$, but SMX was not fully mineralized and converted to intermediates as hydroylated-SMX, sulfanilic acid, 4-aminobenzenesulfinic acid and nitrobenzene. After that these are completely mineralized through organic acid. We proposed the decomposition reaction path ways of SMX by analyzing the behavior of these intermediates. To investigate the durability of heterogeneous catalyst, decomposition of SMX was observed by continuously recycling catalysts. When the heterogeneous catalyst of 10 wt% $Cu/Al_2O_3$ was continuously reused 5 times, decomposition of SMX was a little lowered, but the activity of catalyst was overall very stable.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.131-142
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• 2019

The primary objective of this study was to determine the content of biogenic amines in Korean traditional fermented soybean pastes (doenjang) and to isolate potential probiotic Bacillus sp. with the ability to inhibit biogenic amines accumulation. There were significant differences in the bacterial cell counts, pH value, titratable acidity, salinity, and biogenic amine content between the samples. Among Bacillus strains isolated from doenjang, Bacillus (B.) licheniformis DB102, B. subtilis DB203, B. stearothermophilus DB206, Bacillus sp. DB209, Bacillus sp. DB310, B. coagulans DB311, B. cereus DB313, B. amyloliquefaciens DB714, Bacillus sp. DB917, B. cereus DB 915, B. subtilis DB1020, and Bacillus sp. DB1022 were found to be able to produce biogenic amines. On the other hand, biogenic amine-degrading strains were identified as Bacillus sp. DB403, Bacillus sp. DB407, B. subtilis DB517, B. licheniformis DB612, and B. subtilis DB821. In particular, Bacillus sp. DB407 and B. subtilis DB821 showed probiotic properties including tolerance to artificial digestive juices, adherence to intestinal epithelial cells, resistance to antibiotics, and antibacterial activity against biogenic amine-producing strains. In conclusion, the two probiotic Bacillus strains may be considered as the suitable starter for manufacture of fermented soybean foods with low biogenic amines content.

• Korean Journal of Microbiology
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• v.55 no.3
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• pp.242-247
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• 2019

Biological factors (e.g. microorganism activity) in wastewater treatment plant (WWTP) play essential roles for degradation and/or removal of organic matters. In this study, to understand the microbial functional roles in WWTP, we tried to isolate and characterize a bacterial strain from activated sludge sample. Strain S16 was isolated from the activated sludge of a municipal WWTP in Daejeon metropolitan city, the Republic of Korea. The cells were a Gram-stain-positive, non-motile, facultative anaerobe, and rod-shaped. Strain S16 grew at a temperature of $15{\sim}40^{\circ}C$ (optimum, $30^{\circ}C$), with 0~9.0% (w/v) NaCl (optimum, 1.0~2.0%), and at pH 5.5~9.0 (optimum, pH 7.0~7.5). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain S16 was most closely related to the unique species Miniimonas arenae NBRC $106267^T$ (99.79%, 16S rRNA gene sequence similarity) of the genus Miniimonas. The cell wall contained alanine, glutamic acid, serine, and ornithine. Although the isolation source of the type strain NBRC $106267^T$ which considered as a marine microorganism is sea sand, that of strain S16 is terrestrial environment. It might raise an ecological question for habitat transition. Therefore, comparative genome analysis will be valuable investigation for shedding light on their potential metabolic traits and genomic streamlining.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.3
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• pp.316-322
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• 2019

Helicobacter pylori, a gram-negative bacterium, is one of the risk factors that induces gastritis and gastric cancer. Therefore, much attention has been paid to the compounds that inhibit bacterial growth or eradicate bacteria. Evodiae fructus (EF), the fruit of Evodia rutaecarpa, has been used for treating diarrhea and abdominal pain. EF extract was already found to inhibit the growth of H. pylori. However, to the best of our knowledge, the effect of EF on the virulence factors of H. pylori has not been reported. In this study, when comparing the minimum inhibitory concentration (MIC) of the different methanol concentration extracts, the 95% methanol extract (EF95) showed the lowest MIC value. EF95 extract suppressed the expressions of cagA, vacA and ureB, but interestingly, it up-regulated the expression of ureA. A decrease in production of ammonia in the culture medium and the cell lysates indicated that EF95 inhibited the urease activity in H. pylori, which was the result of EF95 inhibiting the ureB expression. Although the mechanism by which EF95 extract regulates the virulence factors in H. pylori needs further study, EF95 could be used for treatment of gastric troubles induced by H. pylori.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.3
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• pp.323-328
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• 2019

Tuberculosis, a chronic bacterial infection caused by Mycobacterium tuberculosis (MTB), differs in its status latency and activity because of the characteristics of MTB, immune status of the host, and genetic susceptibility. The host defense mechanism against MTB is caused mainly by interactions between macrophages, T cells, and dendritic cells. CD44 is expressed in activated T cells when infected with MTB and regulates lymphocyte migration. In addition, CD44 mediates leukocyte adhesion to the ECM and plays a role in attracting macrophages and $CD4^+$ T cells to the lungs. Therefore, genetic polymorphism of the CD44 gene will inhibit the host cell immune mechanisms against MTB. This study examined whether the genetic polymorphism of the CD44 gene affects the susceptibility of tuberculosis. A total of 237 SNPs corresponding to the CD44 genes were analyzed using the genotype data of 443 tuberculosis cases and 3,228 healthy controls from the Korean Association Resource (KARE). Of these, 17 SNPs showed a significant association with the tuberculosis case. The most significant SNP was rs75137824 (OR=0.231, CI: 1.51~3.56, $P=1.3{\times}10^{-4}$). In addition, rs10488809, one of the 17 significant SNPs, is important for the tuberculosis outbreak can bind to the JUND and FOS transcription factors and can affect CD44 gene expression. This study suggests that polymorphism of the CD44 gene modulates the host susceptibility to tuberculosis in a variety of ways, resulting in differences in the status of tuberculosis.

• Korean Journal of Poultry Science
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• v.49 no.2
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• pp.69-77
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• 2022

Antimicrobial peptides (AMPs) play an important role in innate immunity against pathogenic infections. AMPs exterminate pathogenic bacteria by disrupting cell membranes or inhibiting intracellular molecules. NK-2, first identified in pigs and derived from NK-lysin, has antimicrobial effects against bacteria and parasites. In this study, chimeric peptides (cpNK) of chicken and pig NK-2 and cpNK-derived peptides (cpNK-a1 and cpNK-a2) were synthesized, and their antimicrobial effects against various pathogenic bacteria such as Escherichia coli, Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA) were investigated. The structure of chimeric peptides from chicken and pig NK-2, cpNK, include α-helix like NK-2 and peptide net charge was +9 like porcine NK-2. The cpNK peptide showed powerful bactericidal effects against most bacterial species, including MRSA, especially against gram-negative bacteria. Furthermore, cpNK-derived short peptides, cpNK-a1 and a2 also showed bactericidal activity, but the effects were weaker than those of cpNK. Therefore, we conclude that cpNK- and cpNK-derived short peptides have the potential to be used as antibiotic alternatives.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.2
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• pp.140-148
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• 2022

This study aimed to evaluate the effect of silver diamine fluoride (SDF) and potassium iodide (KI) on the formation of cariogenic biofilm and surface roughness in vitro. A total of 48 bovine dentin specimens with artificially induced caries were prepared and divided into 3 groups of 16: untreated control, SDF-treated, and SDF-treated followed by KI (SDFKI). Ten specimens from each group were used to observe microbial adhesion. Multispecies cariogenic biofilms including Streptococcus mutans, Lactobacillus casei, and Candida albicans were cultured on the specimens. Microbes were cultured for 24 hours, and the colony-forming unit was calculated. The remaining specimens were observed by atomic force microscope and scanning electron microscope (SEM). The number of bacteria was significantly lower in the SDF and SDFKI groups. KI did not inhibit the antibacterial activity of SDF significantly. SEM images showed particles generated after SDF and SDFKI application were deposited on the dentin, but there was no significant difference in surface roughness between the 3 groups. This study confirmed that SDF and SDFKI application did not have a significant effect on the surface roughness of dentin, but effectively inhibited the formation of the early cariogenic bacterial film after 24 hours compared to the control.

• Animal Bioscience
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• v.35 no.12
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• pp.1967-1976
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• 2022

Objective: The aim of this study was to characterize the fecal microbiota of broiler chickens reared in the presence of different shades of light-emitting diode (LED) lights, correlating this information with biochemical and molecular evidence that allowed drawing conclusions on the state of health of the animals. Methods: Overall, the metagenomic approach on fecal samples was associated with evaluations on enzymes involved in the cellular response to oxidative stress: glutathione peroxidase (GPX), superoxide dismutase and catalase; while the inflammatory aspect was studied through the dosage of a proinflammatory cytokine, the interleukin 6 (IL-6), and the evaluation of the matrix metalloproteinases 2 (MMP-2) and 9 (MMP-9). Specifically, analysis was performed on distinct groups of chickens respectively raised in the presence of neutral (K = 3,300 to 3,700), cool (K = 5,500 to 6,000), and warm (K = 3,000 to 2,500) LED lightings, and a direct comparison was performed with animals reared with traditional neon lights. Results: The metagenomic analysis highlighted the presence of two most abundant bacterial phyla, the Firmicutes and the Bacteroidetes, with the latter characterized by a greater relative abundance (p<0.05) in the group of animals reared with Neutral LED light. The analysis on the enzymes involved in the antioxidant response showed an effect of the LED light, regardless of the applied shade, of reducing the expression of GPX (p<0.01), although this parameter is not correlated to an effective reduction in the tissue amount of the enzyme. Regarding the inflammatory state, no differences associated with IL-6 and MMP-9 were found; however, is noteworthy the significant reduction of MMP-2 activity in tissue samples obtained from animals subjected to illumination with neutral LED light. Conclusion: This evidence, combined with the metagenomic findings, supports a potential positive effect of neutral LED lighting on animal welfare, although these considerations must be reflected in more targeted biochemical evaluations.

• Food Science of Animal Resources
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• v.43 no.3
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• pp.402-411
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• 2023

This study was conducted to investigate the bactericidal effect of nisin (Nisin) only, atmospheric pressure plasma (APP) only, and a combination of APP and nisin (APP+Nisin)(APP+Nisin) on beef jerky and sliced ham inoculated with Escherichia coli O157:H7, gram-negative bacteria. The bactericidal effect against E. coli O157:H7 and Listeria monocytogenes was confirmed using a nisin solution at a concentration of 0-100 ppm, and APP+Nisin was tested on beef jerky and sliced ham using 100 ppm nisin. Beef jerky and sliced ham were treated with APP for 5 min and 9 min, respectively. In the bacterial solution, 100 ppm nisin out of 0-100 ppm nisin exhibited the highest bactericidal activity against L. monocytogenes (gram-positive bacteria; p<0.05); however, it did not exhibit bactericidal effects against E. coli O157:H7 (gram-negative bacteria). The APP+Nisin APP+Nisin exhibited a 100% reduction rate in both E. coli O157:H7 and L. monocytogenes compared to the control group, and was more effective than the Nisin. The APP+Nisin decreased the number of colonies formed by 0.80 and 1.96 Log CFU/g for beef jerky and sliced ham, respectively, compared to the control, and exhibited a higher bactericidal effect compared to the Nisin (p<0.05). These results demonstrate the synergistic bactericidal effect of APP and nisin, providing a possible method to improve the limitations of nisin against gram-negative bacteria. In addition, this technology has the potential to be applied to various meats and meat products to control surface microorganisms.

• Journal of Life Science
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• v.33 no.1
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• pp.91-101
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• 2023

Bacteriocins are antimicrobial peptides synthesized on ribosomes, produced by bacteria, that inhibit the growth of similar or closely related bacterial strains. Since the discovery of nisin, many bacteriocins with unique structures and various modes of antibacterial activity have been described, and genes encoding production, secretion, and immunity have been reported. Nisin is one of the bacteriocins applied in cheese, liquid eggs, sauces and canned foods. Many of the bacteriocins of the genus Bacillus belong to lantibiotics, which are modified peptides after translation. Other genus Bacillus also produce many non-lantibiotic bacteriocins. Bacteriocins of the genus Bacillus are sometimes becoming more important because of their broader antibacterial spectrum. Bacteriocins are considered attractive compounds in the food and pharmaceutical industries to prevent food spoilage and growth of pathogenic bacteria. Bacteriocins can be used as biological preservatives in a variety of ways in the food system. Biopreservation refers to extending shelf life and improving safety of foods using microorganisms and/or their metabolites. The demand for new antimicrobial compounds has generated great interest in new technologies that can improve food microbiological safety. Applications of bacteriocins are expanding from food to human health. Today, many researchers are shifting their interest in bacteriocins from food preservation to the treatment of bacteria that cause infections and antibiotic-resistant diseases. This exciting new era in bacteriocin research will undoubtedly lead to new inventions and new applications. In this review, we summarize the various properties and applications of bacteriocins produced by the genus Bacillus.