• Journal of Microbiology and Biotechnology
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• 제28권1호
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• pp.87-94
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• 2018

This study investigated the feasibility of the lytic, tailed Bacillus cereus-specific phage for use in a ferromagnetoelastic (FME) biosensor as a novel recognition element. The phage was immobilized at various concentrations through either direct adsorption or a combination of 11-mercapto-1-undecanoic acid (11-MUA) and [N-(3-dimethylaminopropyl)-N'-carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS)]. The effects of time and temperature on its lytic properties were investigated through the exposure of B. cereus (4 and 8 logCFU/ml) to the phage (8 logPFU/ml) for various incubation periods at $22^{\circ}C$ and at various temperatures for 30 and 60 min. As the phage concentration increased, both immobilization methods also significantly increased the phage density (p < 0.05). SEM images confirmed that the phage density on the FME platform corresponded to the increased phage concentration. As the combination of 11-MUA and EDC/NHS enhanced the phage density and orientation by up to 4.3-fold, it was selected for use. When various incubation was conducted, no significant differences were observed in the survival rate of B. cereus within 30 min, which was in contrast to the significant decreases observed at 45 and 60 min (p < 0.05). In addition, temperature exerted no significant effects on the survival rate across the entire temperature range. This study demonstrated the feasibility of the lytic, tailed B. cereus-specific phage as a novel recognition element for use in an FME biosensor. Thus, the phage could be placed on the surface of foods for at least 30 min without any significant loss of B. cereus, as a result of the inherent lytic activity of the B. cereus-specific phage as a novel recognition element.

• 한국식품저장유통학회지
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• 제30권1호
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• pp.42-51
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• 2023

This study aimed to characterize a lytic Salmonella Typhimurium-specific (ST) phage and its biofilm control capability against S. Typhimurium biofilm on polypropylene surface. ST phage was isolated, propagated, and purified from water used in a slaughterhouse. The morphology of ST phage was observed via transmission electron microscopy. Its bactericidal effect was evaluated by determining bacterial concentrations after the phage treatment at various multiplicities of infection (MOIs) of 0.01, 1.0, and 100. Once the biofilm was formed on the polypropylene tube after incubation at 37℃ for 48 h, the phage was treated and its antibiofilm capability was determined using crystal violet staining and plate count method. The phage was isolated and purified at a final concentration of ~11 log PFU/mL. It was identified as a myophage with an icosahedral head (~104 nm) and contractile tail (~90-115 nm). ST phage could significantly decrease S. Typhimurium population by ~2.8 log CFU/mL at an MOI of 100. After incubation for 48 h, biofilm formation on polypropylene surface was confirmed with a bacterial population of ~6.9 log CFU/cm². After 1 h treatment with ST phage, the bacterial population in the biofilm was reduced by 2.8 log CFU/cm². Therefore, these results suggest that lytic ST phage as a promising biofilm control agent for eradicating S. Typhimurium biofilm formed on food contact surfaces.

• 한국어병학회지
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• 제11권2호
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• pp.137-141
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• 1998

TSB 해수배지와 숙주로서 L. garvieae No. 44를 배양조건으로 사용한 경우, L. garvieae 111균주중 용원화되었다고 추정되어진 96균주의 cells에서 temperate Phage가 효과적으로 분리되었다. 하지만 동일한 배양조건에서 보통의 TSB 배지를 사용한 경우에서는 temperate phage는 전혀 나타나지 않았다. 이 temperate phages는 TSB 해수배지와 ultraviolet irradiation를 병용한 경우 역시 효과적으로 분리되었다. 분리된 모든 temperate Phages는 기존의 phage(PLgY, PLgW, PLgS) 의 lytic nature와는 달리 오직 L.garvieae No. 44만을 lysis하였다. 배양후 약 1시간후 phage가 나타났으며 12시간 후 virulent phage의 최고농도($10^{10}$ PFU/ml) 보다 훨씬 낮은 농도인 $10^6$ PFU/ml까지 증가하였다.

• Journal of Microbiology and Biotechnology
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• 제17권2호
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• pp.262-270
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• 2007

Of the twelve lytic bacteriophages recovered from five different fermenting cucumber tanks that were inoculated with Pediococcus sp. LA0281, a lytic phage, ${\phi}ps05$, was characterized in the present study. The plaques were mostly clear and round-shaped on the lawn of starter strain, indicating lytic phage. Overall appearance indicated that it belongs to the Siphoviridae family or Bradley's group B1, with a small isometric head and a flexible noncontractile tail with swollen base plate. The average size was found to be 51.2 nm in head diameter and 11.6 nm wide ${\times}$ 129.6 nm long for the tail. The single-step growth kinetics curve showed that the eclipse and the latent period were 29 min and 34 min, respectively, and an average burst size was calculated to be 12 particles per infective center. The optimum proliferating temperature ($35^{\circ}C$) was slightly lower than that of cell growth ($35\;to\;40^{\circ}C$). The structural proteins revealed by SDS-PAGE consisted of one main protein of 33 kDa and three minor proteins of 85, 58, and 52 kDa. The phage genome was a linear double-stranded DNA without cohesive ends. Based on the single and double digestion patterns obtained by EcoRI, HindIII, and SalI, the physical map was constructed. The overall size of the phage genome was estimated to be 24.1 kb. The present report describes the presence of a lytic phage active against a commercial starter culture Pediococcus sp. LA0281 in cucumber fermentation, and a preliminary study characterizes the phage on bacterial successions in the process of starter-added cucumber fermentation.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1613-1620
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• 2012

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of many economically important crops. Since there is no promising control strategy for bacterial wilt, phage therapy could be adopted using virulent phages. We used phage PE204 as a model lytic bacteriophage to investigate its biocontrol potential for bacterial wilt on tomato plants. The phage PE204 has a short-tailed icosahedral structure and double-stranded DNA genome similar to that of the members of Podoviridae. PE204 is stable under a wide range of temperature and pH, and is also stable in the presence of the surfactant Silwet L-77. An artificial soil microcosm (ASM) to study phage stability in soil was adopted to investigate phage viability under a controlled system. Whereas phage showed less stability under elevated temperature in the ASM, the presence of host bacteria helped to maintain a stable phage population. Simultaneous treatment of phage PE204 at $10^8$ PFU/ml with R. solanacearum on tomato rhizosphere completely inhibited bacterial wilt occurrence, and amendment of Silwet L-77 at 0.1% to the phage suspension did not impair the disease control activity of PE204. The biocontrol activities of phage PE204 application onto tomato rhizosphere before or after R. solanacearum inoculation were also investigated. Whereas pretreatment with the phage was not effective in the control of bacterial wilt, post-treatment of PE204 delayed bacterial wilt development. Our results suggested that appropriate application of lytic phages to the plant root system with a surfactant such as Silwet L-77 could be used to control the bacterial wilt of crops.

• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1704-1707
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• 2007

Monitoring of the phage-host system of Microlunatus phosphovorus indigenous in activated sludge was attempted. A laboratory-scale activated sludge process was operated for 5 weeks with synthetic wastewater. The phage-host system population in the process was monitored by plaque assay and FISH methods at every 3 days. During the process operation, the phage-host system populations were more or less steady, except for 1 week in the middle of the operation. In that period, initially M. phosphovorus decreased significantly and its lytic bacteriophages increased, and then M. phosphovorus increased back to its original level while its lytic bacteriophages decreased. This observation suggests that lytic bacteriophages should be considered as one of the biological factors affecting the bacterial population dynamics in activated sludge processes.

• 한국미생물·생명공학회지
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• 제11권1호
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• pp.1-4
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• 1983

CaC $l_2$를 제거한 MRT 액체배지에 phage가 MOI =$10^{0}$ 이상으로 감염된 경우에는 0. 15% sodium pyrophosphate 농도에서 유산균이 용균되었으나. 0.175% 이상의 농도에서는 유산균이 정상적으로 증식함을 알 수 있었다. 그러므로 phage 감염 후 유산균의 증식은 sodium pyrophosphate농도와 phage 감염수에 의해 결정된다고 사료된다. 이 때에 sodium pyrophosphate의 phage 증식억제 농도에서 phage불활성화는 나타나지 않았다. 0.15% sodium pyrophosphate를 첨가한 배지에서는 MOI=$10^{-1}$ 이하로 phage가 감염되면 유산균이 증식하여 배양 24시간 후 약 $10^{8-9}$/$m\ell$의 균수를 나타냈으며, 무첨가 배지에서는 MOI =$10^{-3}$ 이상일 때 유산균이 거의 사멸하였고 $10^{-4}$ 일 때는 약 1$\times$$10^{5}$ /$m\ell$로 용균됨을 나타내었다.다.

• 한국미생물·생명공학회지
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• 제10권4호
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• pp.253-258
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• 1982

본 실험의 결과를 요약해 보면 인산염의 종류와 농도에 따라서 유산균의 증식과 phage 감염후의 유산균 증식에 미치는 영향을 검토하였다. 특히, phage 증식억제를 나타내는 물질은 sodium metaphosphate, sodium pyrophosphate, sodium phosphate (dibasic), potassium phosphate(dibasic)으로써 각각 0.2∼0.4%, 0.1∼0.2%, 0.2∼0.3%, 0.2∼0.35%에서 phage 감염 후 유산균의 증식을 가능하게 하였다. 그리고 phage 감염 후에도 증식한 유산균 배양액을 새로운 배지에 1,2차 계대 하였을 때, 역시 인산염의 종류와 농도에 따라 배양액에 존재하는 phage에 의해 유산균의 증식에 큰 영향을 미쳤다. 특히 sodium pyrophosphate의 경우, 0.17%이상에서는 1차 계대 후에도 phage의 증식이 억제되어 유산균이 증식하기 때문에 starter 배양액용 P.R.M제조에 이용이 가능한 것으로 보여 진다.

• Journal of Microbiology and Biotechnology
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• 제16권10호
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• pp.1518-1522
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• 2006

In the present study, it was observed how the phage-host system that is naturally reproduced in activated sludge is affected by the host inoculation. The system of Microlunatus phosphovorus and its phages was selected as the phage-host system native to an activated sludge system operated for 19 days under sequencing anaerobic-aerobic conditions with glutamate as the main carbon source. The phage-host system related to M. phosphovorus was monitored by plaque assay for the phages and by fluorescent in situ hybridization (FISH) for the bacterial host. In addition, the whole phage structure was also monitored by pulsed-field gel electrophoresis (PFGE). During the first 9 days, the phage-host system was more or less steady at approx. 9% (FISH/ DAPI) for M. phosphovorus and approx. 10,000 PFU/ml for its lytic phages. Microlunatus phosphovorus JCM9379 was inoculated into the activated sludge on day 10. Right after the inoculation, M. phosphovorus was approx. 24% (FISH/DAPI) whereas its lytic phages dropped down to approx. 500 PFU/ ml. After the host inoculation (within 9 days), however, the phage-host system eventually reverted to its original level in each population. On the other hand, the whole phage structure was not significantly changed by M. phosphovorus inoculation but stable throughout the process operation. Only the minor change that four phage groups gradually became abundant after the host inoculation was observed.

• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1946-1954
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• 2018

The aim of this study was to isolate and characterize a lytic Yersinia enterocolitica-specific phage (KFS-YE) as a biocontrol agent. KFS-YE was isolated and purified with the final concentration of ($11.72{\pm}0.03$) log PFU/ml from poultry. As observed by transmission electron microscopy, KFS-YE consisted of an icosahedral head and a contractile tail, and was classified in the Myoviridae family. KFS-YE showed excellent narrow specificity against Y. enterocolitica only. Its lytic activity was stable at wide ranges of pH (4-11) and temperature ($4-50^{\circ}C$). The latent period and burst size of KFS-YE were determined to be 45 min and 38 PFU/cell, respectively. KFS-YE showed relatively robust storage stability at -20, 4, and $22^{\circ}C$ for 40 weeks. KFS-YE demonstrated a bactericidal effect in vitro against Y. enterocolitica and provided excellent efficiency with a multiplicity of infection as low as 0.01. This study demonstrated the excellent specificity, stability, and efficacy of KFS-YE as a novel biocontrol agent. KFS-YE may be employed as a practical and promising biocontrol agent against Y. enterocolitica in food.