• Korean Journal of Microbiology
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• v.49 no.3
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• pp.262-269
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• 2013

The object of this study was to improve the quality of Cheonggukjang with new starter, Bacillus subtilis BC-P1. Twenty strains were isolated from the commercial cheonggukjang and 1 Bacillus strain (BC-P1) with protease activity was selected. The 16S rRNA gene sequence revealed that the BC-P1 was closely related to B. subtilis with 99% homology. The quality characteristics of chunggukjang fermented with B. subtilis BC-P1, Bacillus nato (PC) and commercial chunggukjang (NC) were investigated. The characteristics of fermentation were determined by protease, lipase, xylanase, chitinase, and fibrinolytic activities, reducing sugar, nutrient composition and amino acid contents of cheonggukjang sample. Cheonggukjang fermented with B. subtilis BC-P1 showed the strongest fibrinolytic, xylanase, and chitinase activities. Reducung sugar contents of Cheonggukjang samples were $30.16{\pm}2.11$ mg/g (NC), $28.56{\pm}1.52$ mg/g (PC), $32.39{\pm}1.87$ mg/g (BC-P1). And their total amino acid contents were 338.99 mg% (NC), 445.19 mg% (PC), 741.35 mg% (BC-P1). These results suggested that B. subtilis BC-P1 was suitable to be used as a starter to enhance the quality and effects of cheonggukjang.

• Journal of Environmental Health Sciences
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• v.39 no.2
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• pp.166-177
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• 2013

Objectives: The genus Legionella is common in aquatic environments. Some species of Legionella are recognized as potential opportunistic pathogens for human, notably Legionella pneumophila that causes, Legionellosis. Thus, we investigated the contamination of Legionella pneumophila on water supply systems in Seoul, including cooling towers, public baths, hospitals and fountains. Methods: The existence of 16S rRNA and mip gene of L. pneumophila was confirmed in the genome of the isolated strains by PCR. Results: During the summer season of 2010 and 2011, Legionella pneumophila were detected from 163 samples (21.1%) out of 772 samples collected. Among the 163 strains of L. pneumophila, eighty one isolates belonged to serogroup 1 (57.4%), 23 isolates were serogroup 5 (16.3%), 21 isolates were serogroup 6 (14.9%), 8 isolates were serogroup 2 (5.79%), and 8 isolates were identified in serogroup 3 (5.7%). Through PFGE (pulsed-field gel electrophoresis) analysis using Sfi I, genetic types of L. pneumophila were classified into five (A to E) patterns by the band similarity with excess of 70% from public baths. Conclusions: The PFGE patterns of the serotypes showed a tendency for diversity of L. pneumophila. Our results suggest the existence of serological and genetic diversity among the L. pneumophila isolates.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.612-624
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• 2022

A novel Gram-positive, motile, non-spore forming aerobic marine bacterium, designated 107-1^T was isolated from tidal mud collected in Gyehwa-do, South Korea. Cells of strain 107-1^T were short rod or coccoid, oxidase negative, catalase positive and grew at 10-40℃ (with optimum growth at 25-30℃). It utilized menaquinones MK-7 and 8 as its respiratory quinones and its major fatty acids were anteiso-C_15:0 (37.9%), iso-C_16:0 (14.9%), and iso-C_14:0 (10.8%). Phylogenetic analysis based on 16S rRNA gene sequences revealed a distinct clade containing strain 107-1^T and close species Planococcus ruber CW1^T(98.52% sequence similarity), P. faecalis KCTC 33580^T(97.67%), P. kocurii ATCC 43650T(97.48%), P. donghaensis DSM 22276T(97.47%), and P. halocryophilus DSM 24743T(97.37%). Strain 107-1^T contains one circular chromosome (3,513,248bp in length) with G+C content of 44.6 mol%. Estimated ranges for genome to genome distance, average nucleotide identity, and average amino acid identity comparing strain 107-1^T with close taxa were 20.3-34.8%, 77.9-86.9%, and 73.6-92.8%, respectively. Based on polyphasic analysis, strain 107-1^T represents a novel species belonging to the genus Planococcus.

• Journal of Periodontal and Implant Science
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• v.50 no.3
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• pp.171-182
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• 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
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• v.29 no.1
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• pp.40-46
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• 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 Marine Life Science
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• v.1 no.1
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• pp.18-24
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• 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.

• Korean Journal of Food Science and Technology
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• v.44 no.5
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• pp.600-606
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• 2012

A Bacillus sp. that produces fibrinolytic enzyme was isolated from Cheonggukjang, a traditional Korean soybean-fermented food. According to 16S rRNA gene base sequencing, the bacillus was identified as a variety of Bacillus subtilis, and named Bacillus subtilis IDCC 9204. Fibrinolytic enzyme NK-IL9204 was stable up to $60^{\circ}C$ and within pH range of 5-10. Purified NK-IL9204 was detected through fibrin zymography. The molecular weight and isoelectric point of the enzyme were estimated to be 27.7 kDa and 6.7 by SDS-PAGE and 2D electrophoresis, respectively. Its amino acid sequence was similar to that of nattokinase (identities 99.5%) and different from that of nattokinase BPN (identities 86.4%). The plasma fibrinolytic activity of NK-IL9204 was measured by euglobulin clot lysis times (ECLT). The NK-IL9204 was orally administered to SD rats for 3 weeks (1,000 FU/rat/day). The ECLT was significantly shortened by supplementation of NK-IL9204.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1126-1135
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• 2012

In order to produce high-quality fermenting composts, bacteria strains with high activities of extracellular enzymes (cellulase, chitinase, amylase, protease and lipase) were isolated from the soils in 6 provinces of Korea, and characterized by 16S rRNA gene sequence analysis and properties. The selected 7 stains inoculated to livestock manure for 2' fermenting time, and experimental treatment divided into 3 groups, B1, B2 and B3, according to microbial activity and enzyme type. Our results showed that microbe applications (B1, B2 and B3) can increase (p<0.05) both rhizomes (17-38%) and enzyme activities (50-81%) in compost after fermenting time, respectively, compared to non-microbe treatment (control). The microbe application also decreased significantly (p<0.05) the $NH_3$ and $H_2S$ gas contents 13.4 and 27.3% compared with control, and the Propionic acid and Butyric acid gas contents 14.5 and 19.6%, respectively, as compared to the control. The microbial degradation rate (%) of pesticides and heavy metals increased significantly (p<0.05) after fermenting time, respectively, as compared to the control. Especially, microbe applications were more effective in total rhizomes yields and bioactivities than non-microbe treatment. Thus the results of this study could help in development of potential bioinoculants and composting techniques that maybe suitable for crop production, and protectable for earth environment under various conditions.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1883-1895
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• 2018

Alcohol dependence is a global public health problem, yet the mechanisms of alcohol dependence are incompletely understood. The traditional view has been that ethanol alters various neurotransmitters and their receptors in the brain and causes the addiction. However, an increasing amount of experimental evidence suggests that gut microbiota also influence brain functions via gut-to-brain interactions, and may therefore induce the development of alcohol use disorders. In this study, a rat model of alcohol dependence and withdrawal was employed, the gut microbiota composition was analyzed by high-throughput 16S rRNA gene sequencing, and the metagenome function was predicted by PICRUSt software. The results suggested that chronic alcohol consumption did not significantly alter the diversity and richness of gut microbiota in the jejunum and colon, but rather markedly changed the microbiota composition structure in the colon. The phyla Bacteroidetes and eight genera including Bacteroidales S24-7, Ruminococcaceae, Parabacteroides, Butyricimonas, et al were drastically increased, however the genus Lactobacillus and gauvreauii in the colon were significantly decreased in the alcohol dependence group compared with the withdrawal and control groups. The microbial functional prediction analysis revealed that the proportions of amino acid metabolism, polyketide sugar unit biosynthesis and peroxisome were significantly increased in the AD group. This study demonstrated that chronic alcohol consumption has a dramatic effect on the microbiota composition structure in the colon but few effects on the jejunum. Inducement of colonic microbiota dysbiosis due to alcohol abuse seems to be a factor of alcohol dependence, which suggests that modulating colonic microbiota composition might be a potentially new target for treating alcohol addiction.

• Journal of Environmental Health Sciences
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• v.40 no.2
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• pp.88-97
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• 2014

Objectives: The aim of this study was to evaluate the occurrence of microbiological contamination of kitchen utensils and environments of food service operations at university located in Seoul, Korea. Methods: We collected swab samples from the surfaces of knives, chopping boards, floors, and drains, as well as drinking water and airborne bacteria samples from 20 food service operations. Three bacterial indicators and five food poisoning bacteria were measured quantitatively and qualitatively, respectively. We used selective culture media and the PCR assay targeting 16S rRNA gene for the microbiological analysis. Results: We detected bacterial indicators on knives or chopping boards in eight different food service operations and, three food service operations (I, M, and O) showed more than 3 log colony forming units $(CFU)/100cm^2$ on their knives, significantly higher than the others. The levels of bacterial indicators on the floors and drains in the cooking areas were much higher than those on the cooking utensils. S. aureus was detected on 10 floors and 8 drains. Culturable bacteria were identified in 5 drinking water samples, and food service operation B ($431.1CFU/m^3$) and C ($551.2CFU/m^3$) showed more than $400CFU/m^3$ of total airborne bacteria. Conclusions: These results suggest that some of food service operations in this study may require additional investigation to secure the microbial safety of cooking environments. In addition, further actions including hygiene education for employees and proper guidelines to maintain clean cooking environments should be prepared.