• Journal of Food Hygiene and Safety
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• v.14 no.4
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• pp.346-351
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• 1999

To develop a lactic starter to produce antimicrobial substance for inhibiting the growth of a variety of foodborne spoilage bacteria in fermented foods, we investigated the anti-bacterial effect of the antibacterial substance, produced by Lactobacillus amylovorus IMC-1, against foodborne spoilage strains, and its sensitivity on the treatment of proteolytic enzymes. L. amylovorus IMC-1, which was isolated from a traditional cheese in Inner Mongolia, produced a maximum amount of antibacterial substance in the skim milk medium after 72 h incubation at 37$^{\circ}C$, and further incubation resulted in the same activity. The substance obtained from gel filtration inhibited all strains used such as Bacillus subtilis IFO 3025, Staphylococcus aureus IAM 1011, Listeria monocytogenes VTU 206, Escherichia coli RB, and Pseudomonas fragi IFO 3458 at the concentration of 20 units/ml. This substance was found to show bactericidal action against B. subtilis, E. coli, and Ps. fragi, and bacteriostatic activity against both Staph. aureus and L. monocytogenes. The bactericidal action was due to cellular Iysis. The substance is not organic acid, hydrogen peroxide and proteinaceous compound.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.157-161
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• 2002

A lactic acid bacteria with ${\beta}$-gal activity was isolated from Kimchi, a traditional fermented vegetable food in Korea. The isolate was identified as a Lactococcus lactis strain and named L. lactis A2. The gene encoding ${\beta}$-gal of L. lactis A2 was cloned as a 5.8 kb PstI fragment. DNA sequencing identified the complete lacA (galactoside acetyltransferase)-lacZ (${\beta}$-galactosidase) genes together with the 3' part of upstream galT (galactose-1-phosphate uridyltransferase), and the 5'region of downstream galE (UDP-galactose-4-epimerase) genes. L. lactis A2 had the same gal/lac operon structure as in L. lactis subsp. lactis 7962. Other genes of the Leloir pathway are most likely to be located in the 5'upstream of the 5.8 kb fragment on the A2 chromosome. Sequences downstream of galE were different from those of L. lactis subsp. lactis 7962.

• Journal of Life Science
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• v.30 no.10
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• pp.896-904
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• 2020

The purpose of this study was to investigate the probiotic characteristics and immune activities of selected lactic acid bacterial (LAB) strains as feed additives in livestock. 301 LAB strains isolated from traditional fermented foods were first assessed for their antibacterial activity potential. Of the 301 isolates, five showed antibacterial activity against five livestock pathogens (Esherichia coli KCCM11234, Listeria monocytogens KCTC3710, Salmonella Typhimurium KCTC1926, Staphylococcus aureus KCCM11593, and Shigella flexneri KCTC2517). The probiotic characteristics of the five selected strains were also investigated by antioxidative activity, hemolysis, bile salt hydrolase, acid resistance and bile tolerance. The SRCM102607 strain was found to have superior probiotic properties and was selected for further experimentation. 16S rRNA gene sequencing showed that SRCM102607 is Pediococcus acidilactici, which was labeled as P. acidilactici SRCM102607 (KCCM 12246P). The survival characteristics of P. acidilactici SRCM102607 in artificial gastrointestinal conditions were assessed under exposed acidic (pH 2.0) and bile (0.5% and 1.0%) conditions. P. acidilactici SRCM102607 was also confirmed to have resistance to various antibiotics, including amikacin, gentamicin, vancomycin, and etc. The TNF-α production by P. acidilactici SRCM102607 was 171.86±4.00 ng/ml. These results show that P. acidilactici RCM102607 has excellent potential for use as a probiotic livestock feed additive.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.153-159
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• 2013

Lactic acid bacteria are microorganisms that are closely associated with human and/or animal environments, and are categorized as generally recognized as safe (GRAS) organisms due to their ubiquitous appearance in foods and their contribution to the healthy microflora of mucosal surfaces. This study was performed to isolate and identify lactic acid bacteria with antagonistic effects against food-borne pathogens. A total of 3,000 acid-producing bacteria were isolated from infant feces, cattle feces, goat feces, dog feces, pig feces, vaginal tracts, vegetables, fruits, Kimchi, Jeotgal, fermented sausages, raw milk, cheese, yogurt, Cheonggukjang, Meju, and Makgeolli cultured on MRS agar with 0.05% bromocresol purple. For the isolation of bacteriocin-producing bacteria, the diameter of the clear zone was measured on MRS agar plates. Twenty-six isolates exhibited strong antibacterial activity against indicator strains such as Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica serovar Enteritidis. Lactic acid bacteria were identified as Enterococcus faecalis, Enterococcus faecium, Enterococcus hirae, Lactobacillus acidophilus, Lactobacillus amylovorus, Lactobacillus curvatus, Lactobacillus plantarum, and Pediococcus acidilactici by 16S rDNA gene sequence analysis. The results of this study suggest that the isolates could be used as potential probiotic starters for functional food applications.

• Applied Biological Chemistry
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• v.46 no.3
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• pp.165-170
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• 2003

The antioxidative activity of antioxidative substances produced from several bacterial strains isolated from fermented foods were tested by $DPPH\;({\alpha},{\alpha}'-diphenyl-{\beta}-picrylhydrazyl)$ free radical scavenging activity. One of the strains showing the highest antioxidative activity was identified as Bacillus sp. based on the morphological, biochemical, physiological characteristics, and 16S rRNA sequence, and named FF-7. The most optimal medium condition for the production of antioxidative substance from Bacillus sp. FF-7 was 2% galactose as carbon source and l% tryptone as nitrogen source. The antioxidative substance produced from FF-7 in these cultural medium was also tested by in vitro experimental models, the peruxidation of linoleic acid and the peroxidation of rat tissues microsomes by using thiobarbituric acid (TBA) for assay of free malondialdehyde production. The antioxidative activity against lipid peroxidation of rat tissues microsomes was shown in the following order; brain 97.50% > heart 79.95% > kidney 77.84% > spleen 77.47% > testis 69.96% > liver 62.45%. The antioxidative substance produced from FF-7 on linoleic acid peroxidation by IBA method was effectively inhibited during four days, and 0.05% BHT (butylated hydroxytoluene) used comparative control was also effectively inhibited. Results showed that the highest antioxidative activity by DPPH method of antioxidative substance produced from Bacillus sp. FF-7 was obtained by supplementing 2% galactose as carton source and l% tryptone as nitrogen source in cultured medium, this substance effectively inhibited the formation of TBARS in brain microsome in vit개 system and in linoleic acid peroxidation.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.249-253
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• 2017

This study aimed to compare the automated most-probable-number (MPN) TEMPO BC and the quantitative mannitol-egg yolk-polymyxin (MYP) plate methods for enumeration of Bacillus cereus in food samples known to be frequently contaminated. Food products that were naturally or artificially contaminated with B. cereus were analyzed by both methods. A difference of less than 1 log (CFU/g) between the two methods was noted in 95.3% samples. There were no significant differences in artificially contaminated products between the two methods in terms of $R^2$ values for sauce products, jorim products, fish products, etc. However, a significant difference was noted for sunsik, fermented soybean products, and products. The linear equation of naturally versus artificially contaminated food was $log_{(TEMPO\;BC)}=0.8453{\times}log_{(MYP\;plate\;agar)}+0.1642$. Statistical analysis of the results showed good agreement between the two methods. Due to growing interest in food safety, the use of the TEMPO BC method may increase. In response to this trend, the results from this study will offer valuable comparative data on the feasibility of existing methods and help develop new approaches for food safety testing.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.479-486
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• 2019

This study investigated the anti-inflammatory effects of mixed extracts of Achyranthes japonica Nakai (Aj) and Aralia continentalis Kitagawa (Ac) (ratios of 1 : 2, 1 : 3, 1 : 5, 2 : 1, 3 : 1 and 5 : 1) on RAW264.7 macrophages. Cell toxicity was determined using a cell counting kit (CCK) assay. We evaluated anti-inflammatory effects of the mixed extracts of Aj and Ac by measuring interleukin $(IL)-1{\beta}$, IL-6, and tumor necrosis factor $(TNF){\alpha}$ using an enzyme-linked immunosorbent assay (ELISA) kit assay. The mixed extracts of Aj and Ac inhibited lipopolysaccharide (LPS)-induced $IL-1{\beta}$ and $TNF{\alpha}$ in LPS-stimulated macrophages. Comparing different ratios of the mixed extracts, the 2 : 1 ratio of Aj and Ac has much more potency and inhibited the production of $TNF{\alpha}$ in LPS-induced RAW264.7 cells. The results of the present study showed that the mixed extracts of Aj and Ac have potential anti-inflammatory effects on RAW264.7 macrophages. Therefore, these extracts may be used as a good source of functional foods for the protection against inflammatory diseases.

• Food Engineering Progress
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• v.21 no.2
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• pp.132-137
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• 2017

The purpose of this study was to optimize dough properties using response surface methodology (RSM) and to demonstrate the performances of dough prepared under optimized conditions. Dough mixed with yeast, margarine, salt, sugar and wheat flour was prepared by fermentation process. Hardness, cohesiveness and springiness of dough were selected as critical quality attributes. The critical formulations (yeast and water) and process (fermentation time) variables were selected as critical input variables based on preliminary experiment. Box-Behnken design (BBD) was used as RSM. As a result, the quardratic, the squared and the linear model respectively provided the most appropriate fit ($R^2$>90) and had no significant lack of fit (p>0.05) on critical quality attributes (hardness, cohesiveness and springiness). The accurate prediction of dough characteristics was possible from the selected models. It was confirmed by validation that a good correlation was obtained between the actual and predicted values. In conclusion, the methodologies using RSM in this study might be applicable to the optimization of fermented foods containing various wheat flour and yeast.

• Journal of Microbiology and Biotechnology
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• v.33 no.1
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• pp.83-95
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• 2023

These days, bacterial detection methods have some limitations in sensitivity, specificity, and multiple detection. To overcome these, novel detection and identification method is necessary to be developed. Recently, NGS panel method has been suggested to screen, detect, and even identify specific foodborne pathogens in one reaction. In this study, new NGS panel primer sets were developed to target 13 specific virulence factor genes from five types of pathogenic Escherichia coli, Listeria monocytogenes, and Salmonella enterica serovar Typhimurium, respectively. Evaluation of the primer sets using singleplex PCR, crosscheck PCR and multiplex PCR revealed high specificity and selectivity without interference of primers or genomic DNAs. Subsequent NGS panel analysis with six artificially contaminated food samples using those primer sets showed that all target genes were multi-detected in one reaction at 10⁸-10⁵ CFU of target strains. However, a few false-positive results were shown at 10⁶-10⁵ CFU. To validate this NGS panel analysis, three sets of qPCR analyses were independently performed with the same contaminated food samples, showing the similar specificity and selectivity for detection and identification. While this NGS panel still has some issues for detection and identification of specific foodborne pathogens, it has much more advantages, especially multiple detection and identification in one reaction, and it could be improved by further optimized NGS panel primer sets and even by application of a new real-time NGS sequencing technology. Therefore, this study suggests the efficiency and usability of NGS panel for rapid determination of origin strain in various foodborne outbreaks in one reaction.

• Journal of Life Science
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• v.34 no.8
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• pp.576-587
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• 2024

In this study, diverse bacterial strains were isolated from fermented foods to screen those with antibacterial activity. Among them, one strain, identified as Bacillus vallismortis MCBL 1012 through 16S rRNA gene sequence analysis, was selected for its bacteriocin production. The culture supernatant of B. vallismortis MCBL 1012 showed antibacterial activity, mainly against Gram-positive bacteria. Scanning electron microscopy (SEM) revealed that bacteriocin treatment led to cellular content leakages in Listeria monocytogenes KCCM 40307, Enterococcus faecium KCCM 12118, and Streptococcus mutans KCTC 3065. PCR analysis confirmed B. vallismortis MCBL 1012 harbored subtilosin A gene (sbo A). Antibacterial activity was decreased by proteolytic enzymes like proteinase K, subtilisin A, and α-chymotrypsin. The bacteriocin demonstrated stability at 40℃ and 60℃ for 120 min, and up to 80℃ for 60 min, with rapid activity loss at 100℃. It retained full antibacterial activity within a pH range of 4.0 to 8.0 and was not affected by up to 100% organic solvents like ethanol, methanol, acetonitrile, and tetrahydrofuran. Nevertheless, activity decreased with more than 40% isopropanol and 80% acetone. Most tested inorganic salts and detergents had no effect on antibacterial activity except, CuSO₄ and NiSO₄ at specified concentrations. The bacteriocin exerted its antibacterial effect through bactericidal action against L. monocytogenes KCCM 40307. The bacteriocin was purified by ammonium sulfate precipitation, DEAE anion exchange chromatography, and RP-HPLC. The purification resulted in a final yield of 0.03% and a 283.7-fold increase in specific activity. MALDI-TOF MS analysis determined the exact molecular weight of purified bacteriocin to be 3,326.1 Da.