• Journal of Microbiology and Biotechnology
• /
• v.31 no.10
• /
• pp.1420-1429
• /
• 2021

The safety of the probiotic strain Q180, which exerts postprandial lipid-lowering effects, was bioinformatically and phenotypically evaluated. The genome of strain Q180 was completely sequenced, and single circular chromosome of 3,197,263 bp without any plasmid was generated. Phylogenetic and related analyses using16S rRNA gene and whole-genome sequences revealed that strain Q180 is a member of Lactiplantibacillus (Lp., formerly Lactobacillus) plantarum. Antimicrobial resistance (AMR) genes were bioinformatically analyzed using all Lp. plantarum genomes available in GenBank, which showed that AMR genes are present differently depending on Lp. plantarum strains. Bioinformatic analysis demonstrated that some mobile genetic elements such as prophages and insertion sequences were identified in the genome of strain Q180, but because they did not contain harmful genes such as AMR genes and virulence factor (VF)- and toxin-related genes, it was suggested that there is no transferability of harmful genes. The minimum inhibition concentrations of seven tested antibiotics suggested by the European Food Safety Authority guidelines were slightly lower than or equal to the microbiological cut-off values for Lp. plantarum. Strain Q180 did not show hemolytic and gelatinase activities and biogenic amine-producing ability. Taken together, this study demonstrated the safety of strain Q180 in terms of absence of AMR genes and VF- and toxin-related genes as a probiotic strain.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.4
• /
• pp.550-555
• /
• 1997

Vibrio cholerae non-O1 (V. cholerae non-O1) was previously called nonagglutinable or noncholera vibrios, since it fails to react with polyvalent O1 antisera. This organism is biochemically and genetically indistinguishable from V. cholerae O1 except serological difference. V. cholerae non-O1 strains are often detected in the environment including bays, estuaries, and fresh water, and also found in food. Therefore it is designated food borne bacterium in Japan. However, research papers on V. cholerae non-O1 are very rare in Korea. In order to investigate bacteriological characteristics of V. cholerae non-O1, we isolated V. cholerae non-O1 from the environmental sea water. Among the isolated V. cholerae non-O1 strains, we selected the strain which had the most strong hemolytic activity, named as V. cholerae non-O1 FM-3. The optimum growth conditions of V. cholerae non-O1 FM-3 were $37^{\circ}C$ and pH 8.5 in BHI broth (containing $0.5\%$ sodium chloride), and it grew better than V. cholerae non-O1 ATCC 25872. But both were not able to grow in BHI broth added $5.0\%$ of sodium chloride or adjusted to pH 5.0. According to the experimental results on the susceptibility test against various antibiotics, there were no significant differences between the isolated strain and reference strain (V. cholerae non-O1 ATCC 25872). Most of the antibiotics examined had bacteriostatic action against V. cholerae non-O1 FM-3 while vancomycin, oxacillin, colistin, polymyxin B, and sulfadiazine had no bacteriostatic activity.

• Clinical and Experimental Pediatrics
• /
• v.46 no.2
• /
• pp.143-153
• /
• 2003

Purpose : Infection with Shiga-like toxin (SLT)-producing Escherichia coli, an emerging human pathogen found particularly in young children under 5 years of age, causes a spectrum of illnesses with high morbidity and mortality, ranging from diarrhea to hemorrhagic colitis and hemolytic uremic syndrome. Host mediators play an important role in the pathogenesis of SLT-I toxicity. The experiments described here were designed to investigate the effect of SLT-I on TNF-${\alpha}$ production and to understand the effect of TNF-${\alpha}$ on GB3 expression. We also further examine the relationship between the Gb3 level and the differential susceptibility of cells to the cytotoxic action of SLT-I. Methods : The effect of purified SLT-1 from E. coli O157 : H7 (ATCC 43890) on tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) production in Raw264.7 cells was investigated. Many mediators regulate endothelial cell membrane expression of the glycolipid globotriaosyleramide (Gb3), which serves as the toxin receptor, suggesting that the host response to the toxin or other bacterial products may contribute to pathogenesis by regulating target cell sensitivity to the toxins. Therefore, the relationships between Gb3 expression and cytotoxicity against SLT-I on three types of cells were evaluated. Results : Detectable levels of TNF-${\alpha}$ were produced as early as six hours after induction and continued to increase during 48 hours by SLT-I. It was also found that Vero cells and dendritic cells (DC2.4 cells) expressed high levels of Gb3, 83% and 68%, respectively, and that Raw264.7 cells had a low level of Gb3 (29%) and appeared refractory to cytotoxicity against SLT-I. Vero cells and DC2.4 cells expressing high levels of Gb3 were highly susceptible to SLT-I. Furthermore, macrophages showed a resistance to SLT-I cytotoxicity, despite the fact that Gb3 expression was enhanced. Conclusion : These results strongly suggest that the expression of Gb3 is necessary but not sufficient to confer sensitivity of macrophages to SLT-I and further underpin the important role of SLT-I and its Gb3 receptors in the pathogenesis of E. coli O157 infection.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.3
• /
• pp.314-322
• /
• 2009

Four different bacterial colonies were isolated from an old stock of an entomopathogenic nematode, Steinernema monticolum. They all showed entomopathogenicity to final instar larvae of beet armyworm, Spodoptera exigua, by hemocoelic injection. However, they varied in colony form, susceptibility to antibiotics, and postmortem change of the infected host insects. Biolog microbial identification and 16S rDNA sequence analyses indicate that these are four different species classified into different bacterial genera. Owing to high entomopathogenicity and a cadaver color of infected insect host, Serratia sp. was selected as a main symbiotic bacterial species and analyzed for its pathogenicity. Although no virulence of Serratia sp. was detected at oral administration, the bacteria gave significant synergistic pathogenicity to fifth instar S. exigua when it was treated along with a spore-forming entomopathogenic bacterium, Bacillus thuringiensis. The synergistic effect was explained by an immunosuppressive effect of Serratia sp. by its high cytotoxic effect on hemocytes of S. exigua, because Serratia sp. caused septicemia of S. exigua when the bacterial cells were injected into S. exigua hemocoel. The cytotoxic factor(s) was present in the culture medium because the sterilized culture broth possessed high potency in the cytotoxicity, which was specific to granular cells and plasmatocytes, two main immune-associated hemocytes in insects.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.11
• /
• pp.1729-1738
• /
• 2019

In sourdough fermentation, lactic acid bacteria perform important roles in the production of volatile and antimicrobial compounds, and exerting health-promoting effects. In this study, we report the probiotic properties and baking characteristics of Lactobacillus plantarum SPC-SNU 72-2 isolated from kimchi. This strain is safe to use in food fermentation as it does not carry genes for biogenic amine production (i.e., hdc, tdc, and ldc) and shows no β-hemolytic activity against red blood cells. The strain is also stable under simulated human gastrointestinal conditions, showing tolerance to gastric acid and bile salt, and adheres well to colonic epithelial cells. Additionally, this strain prevents pathogen growth and activates mouse peritoneal macrophages by inducing cytokines such as tumor necrosis factor-α, interleukin (IL)-6, and IL-12. Furthermore, the strain possesses good baking properties, providing rich aroma during dough fermentation and contributing to the enhancement of bread texture. Taken together, L. plantarum SPC-SNU 72-2 has the properties of a good starter strain based on the observation that it improves bread flavor and texture while also providing probiotic effects comparable with commercial strains.

• Journal of Veterinary Science
• /
• v.21 no.2
• /
• pp.20.1-20.13
• /
• 2020

Actinobacillus pleuropneumoniae (APP) causes a form of porcine pleuropneumonia that leads to significant economic losses in the swine industry worldwide. The apxIBD gene is responsible for the secretion of the ApxI and ApxII toxins and the pnp gene is responsible for the adaptation of bacteria to cold temperature and a virulence factor. The apxIBD and pnp genes were deleted successfully from APP serotype 1 and 5 by transconjugation and sucrose counter-selection. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants lost hemolytic activity and could not secrete ApxI and ApxII toxins outside the bacteria because both mutants lost the ApxI- and ApxII-secreting proteins by deletion of the apxIBD gene. Besides, the growth of these mutants was defective at low temperatures resulting from the deletion of pnp. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants were significantly attenuated compared with wild-type ones. However, mice vaccinated intraperitoneally with APP5ΔapxIBDΔpnp did not provide any protection when challenged with a 10-times 50% lethal dose of virulent homologous (APP5) and heterologous (APP1) bacterial strains, while mice vaccinated with APP1ΔapxIBDΔpnp offered 75% protection against a homologous challenge. The ΔapxIBDΔpnp mutants were significantly attenuated and gave different protection rate against homologous virulent wild-type APP challenging.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.57 no.3
• /
• pp.216-226
• /
• 2024

This study screened the antimicrobial and anti-inflammatory activities of three extracts [1% acetic acid (HAc), distilled water (D.W.), and ethanol] from the common stalked barnacle Pollicipes mitella. Among the extracts, the 1% HAc extract showed the strongest antibacterial activity against several bacteria, but exhibited no activity against Candida albicans. To improve the degree of separation of the 1% HAc extract, solid-phase extraction was performed using a C18 cartridge with three solvents (D.W., 60A, and 100A). The 1% HAc 60A eluate showed the strongest antibacterial activity and enzyme, salt, and temperature stability, with no hemolytic activity. In addition, strong DNA-binding ability but no bacterial membrane permeability was observed. These results indicate that the P. mitella 1% HAc 60A eluate may contain antibacterial organic compounds that target intracellular components but not bacterial membranes. In addition, the 1% HAc 60A eluate exhibited potent inhibitory activity to reduce the production of inflammatory mediators (nitric oxide and prostaglandin E₂) and pro-inflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-6, and IL-1β) with no cytotoxicity. Therefore, the P. mitella 1% HAc 60A eluate has anti-inflammatory activity. Collectively, our results suggest that the P. mitella 1% HAc 60A eluate can be used as a bioactive source with antibacterial and anti-inflammatory activities.

• Korean Journal of Microbiology
• /
• v.35 no.3
• /
• pp.248-252
• /
• 1999

The PI-oduction of virulence factors such as cholera toxin, heinolysin and hemagglutinin in V cliolerae non-01 and non-0139 were examined. Among 65 strains isolated from environmental and clinical blood sources, 29 (14.6%) strains produced hemolysin only, 35(53.9%) sh.ains produced both hemolysin and hemagglutinin. From one 037 slrain isolated from environmenl, cholera toxin, ctx gene, hemolysin, and hemagglutinin were detected. All of the strains isolated from clinical and environmental sources showed hemolytic activity against human 0 group e~ythrocytes. In inhibition patterns of heinagglotination, 5 of 18 clinical strains (27.8%) were inhibited by less than 1% mannose and galactose, while, among the 47 environmental isolates. hose paltems by less than 1% mannose and galactose 55.4% wel-e inhibited. Thel-ehre, exohamagglutinin positive rate was high in clinical blood isolates but in environnlental sources, the rate was almost similar lo ihe rate or endohemagglutinin positive. These results indicaled that V cholerae non-01 and non-0139 produced various virnlence factors such as cholera toxin, hemolysin, and hemagglutinin but not a single factor. Further studies are need for epidemiological or bacteriological shtdies of V cholerae 037 isolated from environment.

• Journal of Life Science
• /
• v.28 no.12
• /
• pp.1489-1500
• /
• 2018

Honey is made from flower nectar by honey bees. In this study, 120 honeys from various flowers and across eight different provinces in Korea were collected and their components, antioxidants, and hemolytic activities against red blood cell were evaluated. Our results show that total polyphenol (TP) varied widely across the samples, with chestnut honey showing the highest TP ($77.1{\pm}8.4mg/100g$), protein content ($25.9{\pm}0.9mg/100g$), and absorbance at 400 nm ($A_{400}$ : $0.156{\pm}0.036$). In contrast, the acacia honey and sugar honey had a TP of 9.5~30 mg, 12~15 mg/100g of, and the lowest $A_{400}$ of $0.06{\pm}0.02$. High amounts of total flavonoid were quantified in the jujube and chestnut honeys at $8.73{\pm}7.31$ and $8.39{\pm}3.02mg/100g$, respectively. No samples demonstrated hemolytic activity up to 1 mg/ml. Antioxidant activities determined by DPPH, ABTS, and nitrite scavenging placed the chestnut honey highest, followed by jujube, styrax, multi-floral, citrus, acacia and sugar honey. Analysis of parameter correlations indicated that the components and bioactivity of the honey are dependent on the origin of the flower rather than on bee-farming regions. A positive correlation between TP content and antioxidant activity was identified. The correlation coefficients between $A_{400}$ and the TP, ABTS scavenging, and reducing power values were 0.804, 0.772 and 0.741, respectively. We therefore suggest that $A_{400}$ could be used as a noble, economic and simple factor for honey quality evaluation. Our results can potentially be used to develop functional honey for the food and pharmaceutical industries.

• Food Science and Preservation
• /
• v.30 no.6
• /
• pp.1082-1094
• /
• 2023

The purpose of this study was to examine the characteristics of Leuconostoc spp. isolated from radish kimchi and to investigate the potential for the use of functional ingredients by evaluating enzymatic characteristics, safety, and immune-enhancing effects among the isolates, including Lactobacillus rhamnosus ATCC53103 (LGG) as a control strain. All test strains exhibited β-glucosidase enzyme activity that releases β-1,4 sugar chain bonds. In addition, as a result of antibiotic resistance assay among the isolates, MIC values on 8 antibiotics were below compared to the EFSA standard, and hemolytic experiments confirmed that all showed gamma hemolysis without hemolytic ability. As a result of the antibacterial activity experiment, the Leu. mesenteroides K2-4 strain showed a higher activity than LGG against Bacillus cereus and Staphylococcus aureus. Additionally, the activity of the NF-kB/AP-1 transcription factor increased when the isolates were treated in macrophage RAW cells. These results were related to increasing the high mRNA expression levels on TNF-α and IL-6 by Leu. mesenteroides K2-4 strain to be treated at low concentration. Consequently, we suggest that it will be useful as a candidate for functional food ingredients.