• 한국환경보건학회지
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• 제37권5호
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• pp.376-386
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• 2011

Objectives: The aim of this study was to evaluate the microbial hazards posed by food utensils and fixtures in food service operations at selected middle and high schools located in Seoul, Korea. Methods: We collected 200 samples of utensils and fixtures including cups, spoons/chopsticks, food trays and tables from five different schools in Seoul. Target microorganisms of this study were divided into two groups: total bacterial count and total coliform as indicators of microbial contamination and Bacillus cereus and Staphylococcus aureus as pathogens of food poisoning. We used selective media to quantify microbial concentration and 16S rRNA PCR assay for qualitative analysis. In addition, intensive interviews with nutritionists were conducted and observations were made to identify factors that may affect microbial contamination. Logistic regression analysis was employed to examine the relationship between the microbial concentration and operation characteristics of each operation. Results: The level of microbial concentration in school B and C were significantly lower than in school A, D and E (p<0.05). Some samples from school A, D and E showed over 3.4 log CFU/100 $cm^2$ (total bacterial count) and 1.0 log CFU/100 $cm^2$ (total coliform), which requires immediate hygienic action. The number of customers per staff member, periodicity of hygiene education for staff and daily operation time of sterilizers were also found to be important factors related with the microbial contamination of food service operations. Conclusions: These results suggested that not only a HACCP (Hazard Analysis and Critical Control Point) approach, but also efforts to assess internal risk factors within operations be needed to reduce the microbial contamination of food utensils and fixtures. This study is expected to provide preliminary data for assessing microbial hazards in food service operations.

• 한국환경과학회지
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• 제25권6호
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• pp.789-798
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• 2016

Lactic acid bacteria (LAB) are industrially important microorganisms for probiotics. The recent widespread application of LAB for preparation of functional food is attributable to the accumulating scientific evidence showing their beneficial effects on human health. In this study, we isolated and characterized plant-derived LAB that show angiotensin-converting enzyme (ACE) inhibitory and antioxidant activities. The selected strain K2 was isolated from Kimchi, and identified as Lactobacillus plantarum by 16S rRNA gene analysis. The strain grew under static and shaking culture systems. They were also able to grow in different culture conditions like $25^{\circ}C{\sim}37^{\circ}C$ temperature, 4~10 pH range and ~6% NaCl concentration. L. plantarum K2 was highly resistant to acid stress; survival rate of the strain at pH 2.5 and 3 were 80% and 91.6%, respectively. The strain K2 also showed high bile resistance to 0.3% bile bovine and 0.3% bile extract with more than 74% of survival rate. The cell grown on MRS agar plate containing bile extract formed opaque precipitate zones around the colonies, indicating they have bile salt hydrolase activity. The strain showed an inhibitory activity against pathogenic bacteria such as Escherichia coli, Staphylococcus aureus and Listeria monocytogenes; antibacterial activity was probably due to the lactic acid. The K2 strain showed relatively higher autoaggregation values, antihypertensive and antioxidant activities. These results suggest that L. plantarum K2 could be not only applied as a pharmabiotic for human health but also is also starter culture applicable to fermentative products.

• Tuberculosis and Respiratory Diseases
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• 제79권3호
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• pp.165-178
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• 2016

Background: Although recent metagenomic approaches have characterized the distinguished microbial compositions in airways of asthmatics, these results did not reach a consensus due to the small sample size, non-standardization of specimens and medication status. We conducted a metagenomics approach by using terminal restriction fragment length polymorphism (T-RFLP) analysis of the induced whole sputum representing both the cellular and fluid phases in a relative large number of steroid $na{\ddot{i}}ve$ asthmatics. Methods: Induced whole sputum samples obtained from 36 healthy subjects and 89 steroid-$na{\ddot{i}}ve$ asthma patients were analyzed through T-RFLP analysis. Results: In contrast to previous reports about microbiota in the asthmatic airways, the diversity of microbial composition was not significantly different between the controls and asthma patients (p=0.937). In an analysis of similarities, the global R-value showed a statistically significant difference but a very low separation (0.148, p=0.002). The dissimilarity in the bacterial communities between groups was 28.74%, and operational taxonomic units (OTUs) contributing to this difference were as follows: OTU 789 (Lachnospiraceae), 517 (Comamonadaceae, Acetobacteraceae, and Chloroplast), 633 (Prevotella), 645 (Actinobacteria and Propionibacterium acnes), 607 (Lactobacillus buchneri, Lactobacillus otakiensis, Lactobacillus sunkii, and Rhodobacteraceae), and 661 (Acinetobacter, Pseudomonas, and Leptotrichiaceae), and they were significantly more prevalent in the sputum of asthma patients than in the sputum of the controls. Conclusion: Before starting anti-asthmatic treatment, the microbiota in the whole sputum of patients with asthma showed a marginal difference from the microbiota in the whole sputum of the controls.

• 한국축산식품학회지
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• 제31권4호
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• pp.557-562
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• 2011

본 연구는 국내에서 유통되고 있는 액란의 냉장저장 중 미생물 및 이화학적 성상을 구명하기 위해 수행하였다. 본 실험에 사용된 액란은 살균 및 비살균 처리된 전란액, 난황액 및 난백액으로 여름철과 겨울철 생산 제품에 대해 각각 조사하였다. 냉장저장 중 세균수의 경우 여름철에 생산된 비살균 액란(전란액, 난황액 및 난백액)은 1,270-83,300 CFU/g 수준으로 겨울철에 생산된 비살균 액란의 0-4,330 CFU/g 에 비해 증가하는 것으로 나타났다. 살균 전란액과 살균 난황액에서는 저장기간 동안 액란생산 계절과 관계 없이 대장균군이 검출되지 않는 것으로 나타났다. 반면, 비살균 액란은 냉장저장 중 겨울철에 생산된 난백액에서만 대장균군이 검출되지 않는 것으로 나타났다. Salmonella는 살균 및 비살균 액란 모두에서 냉장저장 중 액란 생산 계절과 관계없이 검출되지 않았다. 그러나, 여름철에 생산된 비살균 전란액으로부터 Salmonella 의심균을 동정한 결과, Pseudomonas sp, Pseudomonas geezenne, Pseudomonas otitidis, Pseudomonas aeruginosa인 것으로 판명되었다. 액란의 냉장저장 중 pH 및 점도변화는 살균과 비살균 처리구간 뚜렷한 차이가 없는 것으로 나타났다. 이상의 결과를 종합해 볼 때 여름철에 비살균 액란 생산시 교차오염에 각별한 주의가 필요할 것으로 사료된다.

• Journal of Dairy Science and Biotechnology
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• 제38권2호
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• pp.89-98
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• 2020

본 연구의 목적은 한국 전통 음식 김치에서 분리한 유산균의 특성을 연구하기 위해 형태학적, 생화학적 특성을 조사하였다. 한국의 전통 발효 식품에서 젖산균을 확인하기 위해 분리된 균주의 그람염색을 수행한 후 Macrogen에서 16S rRNA 분석 결과, DKGF9(Lactobacillus plantarum), DKGF1(Lactobacillus paracasei ), DKGF8(Lactobacillus casei ), DK207(Lactobacillus casei ), DK211(Lactobacillus casei )이 확인되었다. 우리는 한국의 전통 발효 식품인 김치에서 분리된 5가지 LAB의 기본 생물학적 활성에 대한 실험을 수행했다. 37℃, 55℃, 65℃, 75℃에서 각각 5분, 15분 5균주의 내열성 확인 결과, 상업 균주인 Lactobacillus acidophilus LA-5의 내열성과 유사하거나 더 높음을 보여주었다. 장내부착능에서는 선발균주 모두 상용균주와 비교했을 때 10⁷ CFU/mL 이상으로 우수한 결합능을 보여주었고, KCTC(한국생명공학연구원 생물자원센터)에서 분양받은 Escherichia coli KCTC1682, Salmonella enterica KCTC2054, Bacillus cereus KCTC3624 3종을 활용한 항균활성 결과, 모든 균주는 상업용 균주인 L. acidophilus LA-5와 비교하여 유사하거나 더 높은 항균 활성을 나타냈다. 단백질분해능력 실험에서, 5개의 균주는 clear-zone의 직경이 24시간에서 72시간으로 갈수록 점차 증가하고, L. paracasei DKGF1이 가장 큰 직경을 갖고 있어 단백질분해능력이 가장 우수한 것으로 나타났다. 5개의 균주로부터 선택된 3개의 균주는 ABTS, DPPH, FRAP, Hydroxyl radical scanenging 활성을 포함하여 다양한 항산화활성 효과를 나타냈다. 결과적으로, 5가지 균주 중에서 우수한 기능성을 갖는 L. paracasei DKGF1이 잠재적인 프로바이오틱스 활성을 나타내며, 건강 관련 제품의 개발에 유용한 균주라고 판단된다.

• 한국식품영양과학회지
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• 제46권9호
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• pp.1114-1121
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• 2017

전통장류로부터 식품 유해요소를 생성하지 않는 Bacillus 균주를 분리하여 세포외효소 활성(amylase, protease, cellulase, xylanase)을 측정한 후, 단백질 분해 활성이 우수한 14개 균주와 비교균주 1균주를 선발하였다. 선발된 균주에 대해 16S rRNA 유전자를 이용한 균주 동정을 실시한 결과, B. amyloliquefaciens 10종, B. methylotrophicus 1종, B. velezensis 1종, B. subtilis 3종이 분리 동정되었다. 그중 B. subtilis JBG17019, B. amyloliquefaciens JBD17076, B. amyloliquefaciens JBD17109 균주에서 식중독미생물에 대한 증식 억제능이 확인되었다. Glutamic acid 대사와 관련한 발효특성을 확인하기 위하여 선발된 Bacillus 균주에 대해 glutamate, glutamine 및 ${\gamma}$-PGA 생성능을 측정하였다. 발효특성과 ${\gamma}$-PGA 생성능에 대한 다변량 요인분석을 주성분(PCA) 추출법으로 분석한 결과, PC1(효소 활성(amylase, cellulase, xylanase), PC2(${\gamma}$-PGA 생성능) 및 PC3(protease, glutamate 및 glutamine)의 3가지 주성분이 분류되었다. 주성분(PC)의 추출에 따라 B. amyloliquefaciens JBD17076 및 B. subtilis JBG17019 균주는 우수한 효소 활성 및 ${\gamma}$-PGA 생성을 하는 것으로 평가되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권9호
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• pp.1464-1473
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• 2018

Objective: To describe in-depth sequencing, the bacterial community diversity and its succession during ensiling of whole-plant maize and subsequent exposure to air. Methods: The microbial community dynamics of fermented whole-plant maize for 60 days (sampled on day 5, 10, 20, 40, 60) and subsequent aerobic exposure (sampled on day 63 after exposure to air for 3 days) were explored using Illumina Miseq sequence platform. Results: A total of 227,220 effective reads were obtained. At the genus level, there were 12 genera with relative abundance >1%, Lactobacillus, Klebsiella, Sporolactobacillus, Norank-c-cyanobacteria, Pantoea, Pediococcus, Rahnella, Sphingomonas, Serratia, Chryseobacterium, Sphingobacterium, and Lactococcus. Lactobacillus consistently dominated the bacterial communities with relative abundance from 49.56% to 64.17% during the ensiling process. Klebsiella was also an important succession bacterium with a decrease tendency from 15.20% to 6.41% during the ensiling process. The genus Sporolactobacillus appeared in late-ensiling stages with 7.70% abundance on day 40 and 5.32% on day 60. After aerobic exposure, the Lactobacillus decreased its abundance from 63.2% on day 60 to 45.03% on d 63, and Klebsiella from 5.51% to 5.64%, while Sporolactobacillus greatly increased its abundance to 28.15%. These bacterial genera belong to 5 phyla: Firmicutes (relative abundance: 56.38% to 78.43%) was dominant, others were Proteobacteria, Bacteroidetes, Cyanobacteria, and Actinobacteria. The bacterial communities clearly clustered into early-ensiling (d 5), medium-ensiling (d 10, d 20), late-ensiling (d 40, d 60), and aerobic exposure (d 63) clusters, with early- and late-ensiling communities more like each other than to the aerobic exposure communities. Conclusion: High-throughput sequencing based on 16S rRNA genes proved to be a useful method to explore bacterial communities of silage. The results indicated that the bacterial communities varied during fermentation and more dramatically during aerobic exposure. The study is valuable for understanding the mechanism of population change and the relationship between bacteria and ensilage characteristics.

• Asian-Australasian Journal of Animal Sciences
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• 제30권11호
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• pp.1660-1666
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• 2017

Objective: Burial is associated with environmental effects such as the contamination of ground or surface water with biological materials generated during the decomposition process. Therefore, bacterial communities in leachates originating from the decomposing bovine carcasses were investigated. Methods: To understand the process of bovine (Hanwoo) carcass decomposition, we simulated burial using a lab-scale reactor with a volume of $5.15m^3$. Leachate samples from 3 carcasses were collected using a peristaltic pump once a month for a period of 5 months, and bacterial communities in samples were identified by pyrosequencing of the 16S rRNA gene. Results: We obtained a total of 110,442 reads from the triplicate samples of various sampling time points (total of 15 samples), and found that the phylum Firmicutes was dominant at most sampling times. Differences in the bacterial communities at the various time points were observed among the triplicate samples. The bacterial communities sampled at 4 months showed the most different compositions. The genera Pseudomonas and Psychrobacter in the phylum Proteobacteria were dominant in all of the samples obtained after 3 months. Bacillaceae, Clostridium, and Clostridiales were found to be predominant after 4 months in the leachate from one carcass, whereas Planococcaceae was found to be a dominant in samples obtained at the first and second months from the other two carcasses. The results showed that potentially pathogenic microbes such as Clostridium derived from bovine leachate could dominate the soil environment of a burial site. Conclusion: Our results indicated that the composition of bacterial communities in leachates of a decomposing bovine shifted continuously during the experimental period, with significant changes detected after 4 months of burial.

• Journal of Microbiology and Biotechnology
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• 제23권12호
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• pp.1717-1725
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• 2013

Traditional soybean paste from Shandong Liangshan and Tianyuan Jiangyuan commercial soybean paste were chosen for analysis and comparison of their bacterial and fungal dynamics using denaturing gel gradient electrophoresis and 16S rRNA gene clone libraries. The bacterial diversity results showed that more than 20 types of bacteria were present in traditional Shandong soybean paste during its fermentation process, whereas only six types of bacteria were present in the commercial soybean paste. The predominant bacteria in the Shandong soybean paste were most closely related to Leuconostoc spp., an uncultured bacterium, Lactococcus lactis, Bacillus licheniformis, Bacillus spp., and Citrobacter freundii. The predominant bacteria in the Tianyuan Jiangyuan soybean paste were most closely related to an uncultured bacterium, Bacillus licheniformis, and an uncultured Leuconostoc spp. The fungal diversity results showed that 10 types of fungi were present in the Shandong soybean paste during the fermentation process, with the predominant fungi being most closely related to Geotrichum spp., an uncultured fungal clone, Aspergillus oryzae, and yeast species. The predominant fungus in the commercial soybean paste was Aspergillus oryzae.

• The Plant Pathology Journal
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• 제31권2호
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• pp.152-164
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• 2015

Biological control of major rice diseases has been attempted in several rice-growing countries in Asia during the last few decades and its application using antagonistic bacteria has proved to be somewhat successful for controlling various fungal diseases in field trials. Two novel endophytic Bacillus species, designated strains YC7007 and $YC7010^T$, with antimicrobial, plant growth-promoting, and systemic resistance-inducing activities were isolated from the roots of rice in paddy fields at Jinju, Korea, and their multifunctional activities were analyzed. Strain YC7007 inhibited mycelial growth of major rice fungal pathogens strongly in vitro. Bacterial blight and panicle blight caused by Xanthomonas oryzae pv. oryzae (KACC 10208) and Burkholderia glumae (KACC 44022), respectively, were also suppressed effectively by drenching a bacterial suspension ($10^7cfu/ml$) of strain YC7007 on the rhizosphere of rice. Additionally, strain YC7007 promoted the growth of rice seedlings with higher germination rates and more tillers than the untreated control. The taxonomic position of the strains was also investigated. Phylogenetic analyses based on 16S rRNA gene sequences indicated that both strains belong to the genus Bacillus, with high similarity to the closely related strains, Bacillus siamensis KACC $15859^T$ (99.67%), Bacillus methylotrophicus KACC $13105^T$ (99.65%), Bacillus amyloliquefaciens subsp. plantarum KACC $17177^T$ (99.60%), and Bacillus tequilensis KACC $15944^T$ (99.45%). The DNA-DNA relatedness value between strain $YC7010^T$ and the most closely related strain, B. siamensis KACC $15859^T$ was $50.4{\pm}3.5%$, but it was $91.5{\pm}11.0%$ between two strains YC7007 and $YC7010^T$, indicating the same species. The major fatty acids of two strains were anteiso-$C_{15:0}$ and iso $C_{15:0}$. Both strains contained MK-7 as a major respiratory quinone system. The G+C contents of the genomic DNA of two strains were 50.5 mol% and 51.2 mol%, respectively. Based on these polyphasic studies, the two strains YC7007 and $YC7010^T$ represent novel species of the genus Bacillus, for which the name Bacillus oryzicola sp. nov. is proposed. The type strain is $YC7010^T$ (= KACC $18228^T$). Taken together, our findings suggest that novel endophytic Bacillus strains can be used for the biological control of rice diseases.