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( Sojeong Heo ),( Jungmin Lee ),( Jong-hoon Lee ),( Do-won Jeong ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.10
To shed light on the genetic basis of salt tolerance in Enterococcus faecium, Enterococcus faecalis, and Tetragenococcus halophilus, we performed comparative genome analysis of 10 E. faecalis, 11 E. faecium, and three T. halophilus strains. Factors involved in salt tolerance that could be used to distinguish the species were identified. Overall, T. halophilus contained a greater number of potassium transport and osmoprotectant synthesis genes compared with the other two species. In particular, our findings suggested that T. halophilus may be the only one among the three species capable of synthesizing glycine betaine from choline, cardiolipin from glycerol and proline from citrate. These molecules are well-known osmoprotectants; thus, we propose that these genes confer the salt tolerance of T. halophilus.
( Sojeong Heo ),( Jung-sug Lee ),( Jong-hoon Lee ),( Do-won Jeong ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.3
To shed light on the genetic differences among food-originated coagulase-negative Staphylococcus (CNS), we performed pan-genome analysis of five species: Staphylococcus carnosus (two strains), Staphylococcus equorum (two strains), Staphylococcus succinus (three strains), Staphylococcus xylosus (two strains), and Staphylococcus saprophyticus (one strain). The pan-genome size increases with each new strain and currently holds about 4,500 genes from 10 genomes. Specific genes were shown to be strain dependent but not species dependent. Most specific genes were of unknown function or encoded restriction-modification enzymes, transposases, or prophages. Our results indicate that unique genes have been acquired or lost by convergent evolution within individual strains.
Safety Assessment Systems for Microbial Starters Derived from Fermented Foods
( Sojeong Heo ),( Tao Kim ),( Hong-eun Na ),( Gawon Lee ),( Jung-hyun Park ),( Hee-jung Park ),( Do-won Jeong ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.10
Microorganisms involved in food fermentation not only improve the aroma and taste of the food, but also enhance its preservation. Thus, they are added as starter cultures to boost the final product quality of commercial fermented foods. Although these microorganisms originate from fermented foods and have a long history of consumption, the European Union recently applied the concept of Qualified presumption of Safety (QPS), which is a safety evaluation system for microorganisms used in food or feed in Europe. The QPS system is a species-level safety system and shares results with the European Novel Food System, a strain-level safety evaluation system. In the United States, microorganisms added to fermented foods are considered as food additives or Generally Recognized as Safe substance. In Korea, food microbe lists are presented at the species level. Moreover, the nation has established a strain-oriented evaluation system that applies temporary safety evaluation methods for food raw materials as well as new raw materials. However, when it comes to microorganisms isolated from traditional fermented foods and other fermented food products, there is no definition of the term “species,” and there is a lack of an evaluation system at the species level. Therefore, such an evaluation system for microbial species used in Korean fermented foods is necessary.
바이오제닉아민 분해 유전자 보유 Bacillus 균주 선발 및 특성
허소정 ( Sojeong Heo ),정근철 ( Keuncheol Jeong ),이현동 ( Hyundong Lee ),정도원 ( Do-won Jeong ),이종훈 ( Jong-hoon Lee ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 한국미생물·생명공학회지 Vol.45 No.2
메주와 된장에서 분리한 Bacillus 속 126균주를 대상으로 amine oxidase 활성을 나타낸 10균주를 분리하였다. 그 중, B. licheniformis 8MI05와 8MS03 균주는 동일한 염기서열을 가진 amine oxidase 유전자(yobN)를 보유하고 있었다. 공개된 B. licheniformis 유전체 정보를 대상으로 yobN 유전자의 보유를 검색한 결과, yobN 유전자 보유는 균주 특이적인 특성으로 확인되었다. 두 균주 모두 4종류 바이오제닉아민(cadaverine, histamine, putrescine, tyramine) 분해 활성을 나타냈고, yobN 유전자를 보유한 재조합균주에서도 바이오제닉아민 분해 활성이 확인되었다. Amine oxidase 유전자보유 균주들은 14% NaCl 농도에서 생육 가능하였고, 균주특이적인 protease 및 lipase 활성을 나타내었다. Ten Bacillus strains possessing amine oxidase activity were selected from 126 Bacillus isolates from meju and doenjang (two traditional Korean soybean foods). Among the isolates, two B. licheniformis strains (8MI05 and 8MS03) harbored the amine oxidase gene yobN. By conducting a gene search against published B. licheniformis genomes, the possession of yobN was proved to be a strain-specific property. Both strains degraded four types of biogenic amines (cadaverine, histamine, putrescine, and tyramine) supplemented in tryptic soy broth during their culture. A recombinant harboring yobN also degraded the four types of bio-genic amines during cultivation. Both Bacillus strains could grow at a NaCl concentration of 14% and exhibited strain-specific protease and lipase activities.
Moon Yura,Heo Sojeong,Park Hee-Jung,Park Hae Woong,Jeong Do-Won 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.12
Leuconostoc lactis strain DMLL10 was isolated from kimchi, a fermented vegetable, as a starter candidate through safety and technological assessments. Strain DMLL10 was susceptible to ampicillin, chloramphenicol, clindamycin, erythromycin, gentamicin, kanamycin, streptomycin, and tetracycline. It did not show any hemolytic activity. Regarding its phenotypic results related to its safety properties, genomic analysis revealed that strain DMLL10 did not encode for any toxin genes such as hemolysin found in the same genus. It did not acquire antibiotic resistance genes either. Strain DMLL10 showed protease activity on agar containing NaCl up to 3%. The genome of DMLL10 encoded for protease genes and possessed genes associated with hetero- and homo-lactic fermentative pathways for lactate production. Finally, strain DMLL10 showed antibacterial activity against seven common foodborne pathogens, although bacteriocin genes were not identified from its genome. These results indicates that strain DMLL10 is a novel starter candidate with safety, enzyme activity, and bacteriocin activity. The complete genomic sequence of DMLL10 will contribute to our understanding of the genetic basis of probiotic properties and allow for assessment of the effectiveness of this strain as a starter or probiotic for use in the food industry.
( Tao Kim ),( Sojeong Heo ),( Hong-eun Na ),( Gawon Lee ),( Jong-hoon Kim ),( Mi-sun Kwak ),( Moon-hee Sung ),( Do-won Jeong ) 한국미생물 · 생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.3
In this study, the bacterial community of galchi-baechu kimchi was determined using culture-based and culture-independent techniques (next generation sequencing:NGS), and showed discrepancies between results. Weissella koreensis and Pediococcus inopinatus were the dominant species according to the NGS results, while Bacillus species and P. inopinatus were dominant in the culture-dependent analysis. To identify safe starter candidates, sixty-five Bacillus strains isolated from galchi-baechu kimchi using culture-dependent methods were evaluated for their antibiotic resistance, presence of toxin genes, and hemolytic activity. Strains were then assessed for salt tolerance and protease and lipase activity. As a result, four strains-B. safensis GN5_10, B. subtilis GN5_19, B. velezensis GN5_25, and B. velezensis GT8-were selected as safe starter candidates for use in fermented foods.
Lee Gawon,Heo Sojeong,Kim Tao,Na Hong-Eun,Park Junghyun,Lee Eungyo,이종훈,정도원 한국미생물·생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.8
Bacillus subtilis is a useful bacterium in the food industry with applications as a starter strain for fermented food and as a probiotic. However, it is difficult to discriminate B. subtilis from other Bacillus species because of high phenotypic and genetic similarity. In this study, we employed five previously constructed multilocus sequence typing (MLST) methods for the discrimination of B. subtilis from other Bacillus species and all five MLST assays clearly distinguished B. subtilis. Additionally, the 17 housekeeping genes used in the five MLST assays also clearly distinguished B. subtilis. The pyruvate carboxylase (pyrA) and shikimate dehydrogenase (aroE) genes were selected for the discrimination of B. subtilis because of their high number of polymorphic sites and the fact that they displayed the lowest homology among the 17 housekeeping genes. Specific primer sets for the pyrA and aroE genes were designed and PCR products were specifically amplified from B. subtilis, demonstrating the high specificity of the two housekeeping genes for B. subtilis. This species-specific PCR method provides a quick, simple, powerful, and reliable alternative to conventional methods in the detection and identification of B. subtilis.
( Jungmin Lee ),( Sojeong Heo ),( Jihoon Choi ),( Minsoo Kim ),( Eunji Pyo ),( Myounghee Lee ),( Sangick Shin ),( Jaehwan Lee ),( Jaehun Sim ),( Do-won Jeong ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.2
Comparative genomic analysis was performed on eight species of lactic acid bacteria (LAB)― Lactococcus (L.) lactis, Lactobacillus (Lb.) plantarum, Lb. casei, Lb. brevis, Leuconostoc (Leu.) mesenteroides, Lb. fermentum, Lb. buchneri, and Lb. curvatus―to assess their glutamic acid production pathways. Glutamic acid is important for umami taste in foods. The only genes for glutamic acid production identified in the eight LAB were for conversion from glutamine in L. lactis and Leu. mesenteroides, and from glucose via citrate in L. lactis. Thus, L. lactis was considered to be potentially the best of the species for glutamic acid production. By biochemical analyses, L. lactis HY7803 was selected for glutamic acid production from among 17 L. lactis strains. Strain HY7803 produced 83.16 pmol/μl glutamic acid from glucose, and exogenous supplementation of citrate increased this to 108.42 pmol/μl. Including glutamic acid, strain HY7803 produced more of 10 free amino acids than L. lactis reference strains IL1403 and ATCC 7962 in the presence of exogenous citrate. The differences in the amino acid profiles of the strains were illuminated by principal component analysis. Our results indicate that L. lactis HY7803 may be a good starter strain for glutamic acid production.
Increased Production of γ-Aminobutyric Acid from Brewer’s Spent Grain Through Bacillus Fermentation
Kim Tao,Heo Sojeong,Na Hong-Eun,Lee Gawon,Lee Jong-Hoon,Kim Ji Yeon,Jeong Do-Won 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.4
Brewer’s spent grain (BSG) is a waste product of the beer industry, and γ-aminobutyric acid (GABA) is a physiologically active substance important for brain and neuron physiology. In this study, we used the bacterial strains Bacillus velezensis DMB06 and B. licheniformis 0DA23-1, respectively, to ferment BSG and produce GABA. The GABA biosynthesis pathways were identified through genomic analysis of the genomes of both strains. We then inoculated the strains into BSG to determine changes in pH, acidity, reducing sugar content, amino-type nitrogen content, and GABA production, which was approximately doubled in BSG inoculated with Bacillus compared to that in uninoculated BSG; however, no significant difference was observed in GABA production between the two bacterial strains. These results provide the experimental basis for expanding the use of BSG by demonstrating the potential gain in increasing GABA production from a waste resource.
글루탐산 생산을 위한 Lactococcus lactis HY7803 균주의 대두 발효 적용
Lee Jungmin,Heo Sojeong,Choi Jihoon,Pyo Eunji,Lee Myounghee,Shin Sangick,Lee Jaehwan,Lee Junglyoul,정도원 한국미생물·생명공학회 2023 한국미생물·생명공학회지 Vol.51 No.1
The glutamic acid producing strain for development savory taste enhancing foods was identified the possibility through application into soybean fermentation. To check the effects on glutamic acid production during soybean fermentation, Lactococcus lactis HY7803 was introduced as a starter. The soybean samples were analyzed on days 0, 7, 14 and 21. The numbers of bacteria decreased gradually, while the content of amino-type nitrogen increased during fermentation in the soybean with L. lactis HY7803. Glutamic acid content in soybeans with L. lactis HY7803 increased from 114.99 ± 9.37 pmol/ul on day 0 to 138.14 ± 1.76 pmol/ul on day 21, showing an overall higher amino acid content than soybeans without L. lactis HY7803 and similar content to soybeans with Aspergillus oryzae SNU-G. It was clearly distinguished through principal component analysis. Consequently, our results indicate that L. lactis HY7803 is available as a fungus replacement and may be a good starter strain for enhancing savory taste in vitro as well as soybean fermentation.