• Journal of Life Science
• /
• v.20 no.2
• /
• pp.269-274
• /
• 2010

An antifungal antibiotic-producing strain, BCNU 2003, was isolated from forest soil in Korea. The morphological and physiological characters, and 16S rRNA sequences analysis of strain BCNU 2003 identified this strain as Bacillus genus. The Bacillus sp. BCNU 2003 showed strong antifungal activities against Aspergillus niger, Trichophyton mentagrophytes and Trichophyton rubrum with inhibition ranging from 62.05 to 63.49% by using dual culture technique. Bacillus sp. BCNU 2003 produced a maximum level of antifungal substances under aerobic incubation at 28oC and pH 6.5-7.2 for 6 days in LB broth. Ethyl acetate extract of the cultured broth showed strong antifungal activity and a broad antifungal spectrum against various pathogenic fungi. The minimum inhibitory concentration (MIC) values for its active extracts ranged between 0.0625 mg/ml and 1 mg/ml. In addition, Bacillus sp. BCNU 2003 was determined to have the ability to produce enzymes such as amylase, protease, gelatinase and catalase.

• Journal of Food Hygiene and Safety
• /
• v.33 no.5
• /
• pp.369-374
• /
• 2018

In this study, Lactobacillus brevis SM61 from traditional Kimchi was used for fermentation of aqueous extract of P. brevitarsis larva and mountain ginseng. As measured by MTT assay, aqueous extract of P. brevitarsis larva and fermented mixture of aqueous extract and mountain ginseng did not show specific cellular toxicity in RAW264.7 cells until a concentration of $5-1000{\mu}g/mL$. The polyphenol contents was highest in the fermented mixture of aqueous extract and mountain ginseng. DPPH radical scavenging activity was stronger in the fermented mixture of aqueous extract and mountain ginseng than the aqueous extract. Also, antibacterial activity was tested against E. coli, L. monocytogenes and S. aureus. The fermented mixture of aqueous extract and mountain ginseng showed antibacterial activity against the tested bacteria. Therefore, L. brevis SM61 as a starter might be used to improve functionality of P. brevitarsis larva.

• Journal of Periodontal and Implant Science
• /
• v.50 no.3
• /
• pp.171-182
• /
• 2020

Purpose: The aims of this study were to examine the salivary microbiota in conditions of periodontal health and disease and to explore microbial changes following nonsurgical periodontal treatment. Methods: Non-stimulated saliva samples were collected from 4 periodontally healthy participants at baseline and from 8 patients with chronic periodontitis at baseline and 3 months following nonsurgical periodontal therapy. The V3 and V4 regions of the 16S rRNA gene from the DNA of saliva samples were amplified and sequenced. The salivary microbial compositions of the healthy participants and patients with periodontitis prior to and following nonsurgical treatment of periodontitis were compared based on the relative abundance of various taxa. Results: On average, 299 operational taxonomic units were identified in each sample. The phylogenetic diversity in patients with periodontitis was higher than that in healthy participants and decreased following treatment. The abundance of the phylum Spirochaetes and the genus Treponema in patients with periodontitis was 143- and 134-fold higher than in the healthy control group, respectively, but decreased significantly following treatment. The species that were overabundant in the saliva of patients with periodontitis included the Peptostreptococcus stomatis group, Porphyromonas gingivalis, the Fusobacterium nucleatum group, Parvimonas micra, Porphyromonas endodontalis, Filifactor alocis, and Tannerella forsythia. The phylum Actinobacteria, the genus Streptococcaceae_uc, and the species Streptococcus salivarius group were more abundant in healthy participants than in those with periodontitis. There was a trend toward a decrease in disease-associated taxa and an increase in health-associated taxa following treatment. Conclusions: Our results revealed differences in the taxa of salivary microbiota between conditions of periodontal health and disease. The taxa found to be associated with health or disease have potential for use as salivary biomarkers for periodontal health or disease.

• Journal of Food Hygiene and Safety
• /
• v.29 no.1
• /
• pp.40-46
• /
• 2014

We have screened Bacillus strains suitable for the fermentation of soybean products with respect to the control of Bacillus cereus and the reduction of biogenic amines. Of 26 isolates, a strain named as the SCK A08 carried antimicrobial activity against B. cereus and Staphylococcus aureus, major food poisoning species in soybean products. PCR analysis revealed that the SCK A08 strain did not contain genes for Bacillus cereus toxins including nonhemolytic enterotoxin, hemolytic enterotoxin, cytotoxin K, cereulide and certrax. The SCK A08 strain could degrade histamine, tyramine, putrescine, and cadaverine by 67.41%, 76.59%, 57.32%, and 50.69%, respectively, during fermentation in cooked soybeans containing 0.5% (w/w) of each biogenic amine. The morphological and biochemical properties and phylogenetic relationships based on 16S rRNA gene sequences indicated that the isolate was most closely related to Bacillus licheniformis. Use of the strain SCK A08 would be a potential measure to overcome two hygienic problems that were frequently faced during manufacture of traditionally fermented soybean products.

• Journal of Life Science
• /
• v.31 no.10
• /
• pp.922-928
• /
• 2021

To profile the microbial compositions of Korean traditional fermented paste made from whole soybeans, Doenjang and Cheonggukjang, and compare their taxonomic differences, we analyzed the V3-V4 region of 16S rRNA of naturally fermented foods by using next generation sequencing. α-Diversity results showed that values indicating bacterial community abundances (OTUs) and richness (ACE, Chao1) were statistically significant (p=0.0001) in Doenjang and Cheonggukjang. Firmicutes was the most common phylum in both groups, representing 97.02% and 99.67% in the Doenjang and Cheonggukjang groups, respectively. Bacillus was the most dominant genus, accounting for 71.70% and 59.87% in both groups. Linear discriminant (LDA) effect size (LEfSe) analysis was performed to reveal the significant ranking of abundant taxa in different fermented foods. A size-effect threshold of 2.0 on the logarithmic LDA score was used for discriminative functional biomarkers. On the species level, Bacillus subtilis, Tetragenococcus halophilus, and Clostridium arbusti were significantly more abundant in Doenjang than in Cheonggukjang, whereas Bacillus thermoamylovorans, Enterococcus faecium, and Lactobacillus sakei were significantly more abundant in Cheonggukjang than in Doenjang. Permutational multivariate analysis of variance (PERMANOVA) showed that the statistical difference in microbial clusters between the two groups was significant at the confidence level of p=0.001. This research could be used as basic research to identify the correlation between the biochemical characteristics of Korean fermented foods and the distribution of microbial communities.

• Korean Journal of Food Science and Technology
• /
• v.53 no.6
• /
• pp.775-784
• /
• 2021

After isolating the DIMO 52 strain with a large inhibition zone diameter for Clostridium perfringens and maximum butyric acid production from the fecal sample of a breastfeeding infant, it was identified as Clostidium butyricum. The maximum growth of the DIMO 52 strain was reached 24 h after inoculation, and the maximum butyric acid concentration was approximately 34.73±4.27 mM. The DIMO 52 strain survived approximately 67.5% of the initial inoculum at pH 2.0, and approximately 64.9% survived in RCM broth supplemented with 0.3% (w/v) oxgall. In addition, DIMO 52 showed antibacterial activity against Escherichia coli KCTC 2441 and Salmonella Typhimurium KCTC 1925. In LPS-stimulated RAW264.7 cells, 1×10³ CFU/mL viable cells of the DIMO 52 strain also exhibited significant NO (nitric oxide) production inhibitory activity (33%, p<0.01). This result suggests that C. butyricum DIMO 52 has anti-inflammatory activity related to NO radical-scavenging activity. In conclusion, C. butyricum DIMO 52 isolated in this study has the potential to be used as a probiotic.

• Journal of Life Science
• /
• v.33 no.1
• /
• pp.25-33
• /
• 2023

The fermentation process of kimchi, which is a traditional Korean food, influences the resulting compo- sition of microorganisms, such as the genera Leuconostoc, Weissella, and Lactobacillus. In addition, several factors, including the type of kimchi, fermentation conditions, materials, and ingredients, can influence the distribution of the kimchi microbial community. In this study, next-generation sequencing (NGS) of kimchi samples obtained from central (Gangwon-do and Gyeonggi-do) and southern (Jeolla-do and Gyeongsang-do) regions in Korea was performed, and the microbial communities in samples from the two regions were compared. Good's coverage prediction for all samples was higher than 99%, indicating that there was sufficient reliability for comparative analysis. However, in a α -diversity analysis, there was no significant difference in species richness and diversity between samples. The Firmicutes phylum was common in both regions. At the species level, Weissella kandleri dominated in central (46.5%) and southern (30.8%) regions. Linear discriminant analysis effect size (LEfSe) analysis was performed to identify biomarkers representing the microbial community in each region. The LEfSe results pointed to statistically significant differences between the two regions in community composition, with Leuconostocaceae (71.4%) dominating in the central region and Lactobacillaceae (61.0%) dominating in the southern region. Based on these results, it can be concluded that the microbial communities of kimchi are significantly influenced by regional properties and that it can provide more useful scientific data to study the relationship between regional characteristics of kimchi and their microbial distribution.

• Journal of Marine Life Science
• /
• v.1 no.1
• /
• pp.18-24
• /
• 2016

Since April 2012, doctor fish in the breeding tank and in the quarantine tank in Hanwha Aquaplanet Yeosu Aquarium have been dying, accompanied by diffuse bleeding around the mouth, in the chin, and at the bottom of the abdomen. In this study, the cause of death would be examined through the bacteriological study of doctor fish and the rearing water quality in the aquarium. The water quality and the bacterial counts of the rearing water in the exhibit tank and in the quarantine tank were analyzed once a week, starting from August to November 2014. Water quality was measured based on the following data: temperature was in the range of 24.5~26.8℃, pH at 6.77~7.94, DO at 6.15~8.61 ppm, ammonia at 0~0.93 ppm, nitrite at 0.009~0.075 ppm, and nitrate at 1.1~40.9 ppm. Studies revealed that the differences in these water quality factors were not related to the death of doctor fish. Bacterial counts in the rearing waters of Garra rufa slightly increased to 10³~10⁴ CFU/ml, just before the death of the doctor fish. Twelve strains of bacteria were isolated from the dead fish and rearing waters. The isolates were identified as Aeromonas veronii, Citrobacter freundii, Pseudorhodoferax aquiterrae, Shewanella putrefaciens, and Vibrio anguillarum on the basis of 16S rRNA gene sequences. The most dominant species was C. freundii, which showed medium sensitivity to florfenicol and norfloxacin, and was resistant to amoxacillin, doxycycline, oxytetracycline, tetracycline, and trimethoprim. Ten isolates were confirmed to be pathogenic to the doctor fish. Doctor fish infected with C. freundii and S. putrefaciens showed high mortality in the experimental groups. These results indicate that the variation in bacterial numbers in the rearing water was related to the death of doctor fish. C. freundii and S. putrefaciens were directly implicated in causing the death of doctor fish in the aquarium.

• The Korean Journal of Pesticide Science
• /
• v.18 no.4
• /
• pp.383-395
• /
• 2014

When we investigated seed infestation by fungal pathogens from 51 varieties in 9 crops, the contamination rate of rice and sesame seeds was high. Therefore, to control seed-borne diseases, we obtained extracts from commercial products of Kimchi, Gochujang, Doenjang, Ganjang, Makgeolli and Tohajut and their suppressive effects against seed-borne diseases were studied. In addition, bacterial strains were screened to control rice seed-borne diseases in vitro and in vivo. Among forty food extracts, eleven food-extracts suppressed incidence of seedling rots in vitro and five food extracts increased 8-33% of healthy seedling in the greenhouse. Among 218 isolates from 40 fermented foods, 43 isolates showed high antifungal activity against seven fungal pathogens. When we tested 43 isolates for the reduction of rice seed borne disease, 32 isolates were able to reduce the rice seed borne disease. Among 32 isolates, 17 isolates reduced significantly seedling rot and increased healthy seedlings, the other isolates except for Kc4-2 and Mkl 2-2 increased shoot emergence and the percentage of healthy plants. Thirty isolates with high antifungal activity and suppressive effect against rice seedling rots were identified by 16S rRNA sequencing. Twenty one of thirty isolates were identified as Bacillus spp. Three isolates from Makgeolli were identified as Saccharomyces cerevisiae. B. amyloliquifaciens were isolated from six Korean traditional fermented foods except for Ganjang. B. amyloliquifaciens were majority in the effective bacterial population of Gochujang and Jutgal. Relatively diverse Bacillus species including B. subtilis, B. pumilus, and B. amyloliquificiens were isolated from Kimchi. The selected effective microorganisms from Korean fermented foods founded to be effective for controlling seed-borne diseases of rice in vitro and in the greenhouse. We think that Korean fermented foods and their useful microorganisms can be used as biocontrol agents for suppressing rice seed-borne diseases based on above described results.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.42 no.3
• /
• pp.434-440
• /
• 2013

This study was conducted to screen the characteristics and alginate-degrading activity of marine bacterium isolated from brown seaweed (Sargassum thunbergii). The results of 16S ribosomal RNA sequence analysis the strain the genus Vibrio and the strain was subsequently named Vibrio sp. PKA 1003. The optimum culture conditions for the growth of Vibrio sp. PKA 1003 were at pH 7, 3% NaCl, $25^{\circ}C$, and 6% alginic acid, with a 48-hour incubation time. A crude enzyme preparation from Vibrio sp. PKA 1003, showed its highest levels of alginate-degradation activity when cultured at pH 9, $30^{\circ}C$, and 6% alginic acid, with a 63-hour incubation time. Thin layer chromatography analyses confirmed that the crude enzyme released monomers or oligomers from sodium alginate, and results from trypsin treatment showed that the alginate degrading activity depends on this enzyme produced by Vibrio sp. PKA 1003. These results suggest that Vibrio sp. PKA 1003 and its alginate-degrading crude enzyme is useful for the production of alginate oligosaccharides.