Young-Duck Lee

Complete Genome Sequence of Enterococcal Bacteriophage SAP6

ABSTRACT Enterococcus faecalis is an important bacterium for use as a probiotic and is an opportunistic pathogen in human beings. The antibiotic resistance acquired by E. faecalis is restricted to antibiotics used in the clinical setting. While screening for alternative antibiotics for use against multidrug-resistant E. faecalis, we isolated a virulent enterococcal bacteriophage, SAP6, belonging to the family Siphoviridae. To our knowledge, this study is the first to report the complete genome sequence of bacteriophage SAP6, which might be used as a therapeutic agent in combination with alternative antibiotics for multidrug-resistant E. faecalis.

Complete Genome of Temperate Phage ENT39118 from Cronobacter sakazakii

ABSTRACT Cronobacter sakazakii infection is particularly harmful to infants, and putative virulence factors of prophage origin have been identified in C. sakazakii. In this study, the phage ENT39118 was isolated from wild-type C. sakazakii; it belongs to the family Siphoviridae. The genomic sequence of phage ENT39118 was composed of circular double-stranded DNA with a length of 39,012 bp. The sequence of ENT39118 showed weak sequence similarity to some reported regions of the prophage sequences in the C. sakazakii BAA-894 genome. To our knowledge, this is the first study of the genomic sequencing and annotation of this temperate phage, which was obtained from a C. sakazakii isolate from powdered infant formula.

Biocontrol of Biofilm-forming Bacillus cereus by Using Organic Acid, Ethanol, and Sodium Chloride

Food poisoning by Bacillus cereus is one of the common food-borne diseases and B. cereus is widely distributed in natural and commercial products owing to the strong resistance caused by biofilm or spore. The ethanol, NaCl, and organic acids of acetic acid, citric acid, and lactic acid for biocontrol of biofilm-forming B. cereus on glass wool were investigated. The biofilm on glass wool was observed in many developments after 48 h incubation. As the results of reduction of biofilm-forming B. cereus by sanitizers, reduction levels of each organic acid treatment ranged to 5-6 log CFU/g-glass wool. In case of combination treatments of 20% ethanol, 10% NaCl, and 1% of each organic acid for 1-5 min, the reduction level of biofilm-forming B. cereus was 7-8 log CFU/g-glass wool. Therefore, combination treatments of ethanol, NaCl, and an organic acid might effectively reduce biofilm-forming B. cereus in various food processes and industries.

Microbial Prevalence and Quality of Organic Farm Produce from Various Production Sites

To analyze the presence of microbes in organic farm produce, green chillies, lettuce, tomatoes, apples, pears, and rice were collected at 47 production sites with organic and conventional produce. Total average bacterial counts of 4.07 log CFU/g in organic green chillies, 3.71 log CFU/g in conventional green chillies, and 6.766.90 log CFU/g in the both lettuce were detected. Mean bacterial counts of 4.48 log CFU/g and 2.84 log CFU/g were detected in organic and conventional pear produce, respectively. Differences in bacterial counts in tomatoes, apples, and rice in organic and conventional produce were less pronounced. Clostridium perfringens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus were not detected in any produce sample. However, Bacillus cereus was detected with average counts of 1.04 log CFU/g in 11/47 (23%) conventional produce samples and 1.97 log CFU/g in 6/ 47 (13%) organic produce samples. Therefore, organic and conventional produce showed similar microbial prevalence patterns, and comparable safety in terms of pathogen contamination.

Characteristics and growth inhibition of isolated bacteriophages for Enterococcus faecalis

Enterococcus faecalis has been used as a starter for fermented food and probiotics, but it can produce biogenic amine in foods and also cause infectious diseases in humans. The antibiotic resistance acquired by E. faecalis restricts antibiotic prescriptions in clinical settings. Bacteriophages EFP4 and EFP7 for E. faecalis, isolated from soil samples, impeded E. faecalis growth. Morphological analysis showed that bacteriophages EFP4 and EFP7 belonged to the Siphoviridae. Bacteriophages EFP4 and EFP7 were susceptible to temperatures above 70°C; however, stability was slightly reduced to 2–3 log PFU/mL after 30 min in 70% ethanol. Two bacteriophages did not suffer phage resistant in E. faecalis for 24 h. Therefore, bacteriophages EFP4 and EFP7, after more study, are candidates for use in biocontrol and controlled fermentation of E. faecalis through food applications.

Virulent Bacteriophage for Growth Inhibition of Cronobacter sakazakii and Salmonella enterica Typhimurium

Cronobacter sakazakii and Salmonella enterica Typhimurium are hazardous pathogens, especially for ready-toeat foods. For control of pathogens, the virulent bacteriophages were isolated, identified, and applied to infant formula milk and vegetable juice. The phages were isolated from swine feces and identified by morphology and molecular characteristics. ES2 phage for C. sakazakii and ST2 phage for S enterica Typhimurium were identified as Myoviridae and Siphoviridae, respectively. Their burst sizes were 52±5 PFU/cell for ES2 phage and 21±3 PFU/cell for ST2 phage after latent period of 30-40 minutes. ST2 phage showed higher heat stability at 60℃ than ES2 phage. ES2 phage held the growth of C. sakazakii untill 6 hr afterwhich the number decreased when applied to the infant formula milk and vegetable juice. ST2 phage also showed growth inhibition so that the number of S. enterica Typhimurium decreased. Therefore, virulent bacteriophages might be an agent for the growth inhibition of C. sakazakii and S. enterica Typhimurium in such the ready-to-eat foods.Cronobacter sakazakii and Salmonella enterica Typhimurium are hazardous pathogens, especially for ready-to- eat foods. For control of pathogens, the virulent bacteriophages were isolated, identified, and applied to infant formula milk and vegetable juice. The phages were isolated from swine feces and identified by morphology and molecular characteristics. ES2 phage for C. sakazakii and ST2 phage for S enterica Typhimurium were identified as Myoviridae and Siphoviridae, respectively. Their burst sizes were 52±5 PFU/cell for ES2 phage and 21±3 PFU/cell for ST2 phage after latent period of 30-40 minutes. ST2 phage showed higher heat stability at 60 o C than ES2 phage. ES2 phage held the growth of C. sakazakii untill 6 hr afterwhich the number decreased when applied to the infant formula milk and vegetable juice. ST2 phage also showed growth inhibition so that the number of S. enterica Typhimurium decreased. Therefore, virulent bacteriophages might be an agent for the growth inhibition of C. sakazakii and S. enterica Typhimurium in such the ready-to-eat foods.

Genome Analysis of Phage SMSAP5 as Candidate of Biocontrol for Staphylococcus aureus.

In this study, we reported the morphogenetic analysis and genome sequence by genomic analysis of the newly isolated staphylococcal phage SMSAP5 from soil of slaughterhouses for cattle. Based on transmission electron microscopy evident morphology, phage SMSAP5 belonged to the Siphoviridae family. Phage SMSAP5 had a double-stranded DNA genome with a length of 45,552 bp and 33 % G+C content. Bioinformatics analysis of the phage genome revealed 43 open reading frames. A blastn search revealed that its nucleotide sequence shared a high degree of similarity with that of the Staphylococcus phage tp310-2. In conclusion, this study is the first report to show the morphological features and the complete genome sequence of the phage SMSAP5 from soil of slaughterhouses for cattle.

Growth Inhibition of Listeria monocytogenes by Weissella spp. from Kimchi Through Real-time PCR

ABSTRACT - Weissella spp. from traditional Korean foods of Kimchi were isolated and characterized againstfood-borne pathogenic Listeria monocytogens. The isolates were identified as W. cibaria 0D17 and W. confusa 0D23from Kimchi by the biochemical characteristics and 16S DNA sequencing. The culture solutions of the isolatesadjusted to pH 7.0 showed L. monocytogens inhibition. To analyze the quantitative detection of L. monocytogenes,real-time PCR was performed according to the SYBR Green I method. The isolates grew well and L. monocytogensdid not grow during the co-culture with those strains at 37 o C. Therefore, W. cibaria 0D17 and W. confusa 0D23 mightbe the candidates as the functional lactic acid bacteria for improving food safety.Key words : Weissella spp., L. monocytogenes, Kimchi, Real-time PCR, Inhibition 유산균은 과거부터 현재까지 오랜 시간 동안 식품 발효에 사용되어 왔으며, 발효 동안 생산되는 다양한 영양 물질, 향기 성분, 항균 물질 등 식품의 풍미와 제품 수명에영향을 주는 것으로 알려져 있다. 그리고 probiotics로서 사람의 장내에 서식하면서 장내 균총 개선, 면역 조절 작용,콜레스테롤 저하, 병원성 세균들의 생육 억제, 유당 불내증 개선 등의 다양한 역할을 하는 것으로 알려져 있다

Isolation and Characterization of Temperate Phages in Enterococcus faecium from Sprouts

Department of Food Science and Engineering, Seowon UniversityAbstract To analyze the characteristics of bacteriophages in Enterococcus faecium, D-19 and F6 phages were inducedfrom five E. faecium isolated from sprouts by the treatment with mitomycin C. The bacteriophages of D-19 and F-6 hadlong, non-contractile tails and icosahedral heads, and were members of Siphoviridae family. As the host spectrum, D-19phage lysed five out of 55 strains of E. faecium, whereas F6 phage lysed only three strains. Both D-19 and F6 phagesdisplayed similar and high stabilities against ethanol and pH capable of resisting the exposure to 100% ethanol and pH 4.Keywords: Enterococcus faecium , temperate phage, Siphoviridae, host spectrum, stability