Characterization of LysPBC4, a novel<i>Bacillus cereus</i>-specific endolysin of bacteriophage PBC4

Na, Hongjun,Kong, Minsuk,Ryu, Sangryeol,Millard, Andrew Oxford University Press 2016 FEMS microbiology letters Vol.363 No.12

LysPBC2, a Novel Endolysin Harboring a <i>Bacillus cereus</i> Spore Binding Domain

Kong, Minsuk,Na, Hongjun,Ha, Nam-Chul,Ryu, Sangryeol American Society for Microbiology 2019 Applied and environmental microbiology Vol.85 No.5

<P>Bacteriophages produce highly evolved lytic enzymes, called endolysins, to lyse peptidoglycan and release their progeny from bacterial cells. Due to their potent lytic activity and specificity, the use of endolysins has gained increasing attention as a natural alternative to antibiotics. Since most endolysins from Gram-positive-bacterium-infecting phages have a modular structure, understanding the function of each domain is crucial to make effective endolysin-based therapeutics. Here, we report the functional and biochemical characterization of a <I>Bacillus cereus</I> phage endolysin, LysPBC2, which has an unusual spore binding domain and a cell wall binding domain. A single point mutation in the spore binding domain greatly enhanced the lytic activity of endolysin at the cost of reduced thermostability. This work contributes to the understanding of the role of each domain in LysPBC2 and will provide insight for the rational design of efficient antimicrobials or diagnostic tools for controlling <I>B. cereus</I>.</P><P>To control the spore-forming human pathogen <I>Bacillus cereus</I>, we isolated and characterized a novel endolysin, LysPBC2, from a newly isolated <I>B. cereus</I> phage, PBC2. Compared to the narrow host range of phage PBC2, LysPBC2 showed very broad lytic activity against all <I>Bacillus</I>, <I>Listeria</I>, and <I>Clostridium</I> species tested. In addition to a catalytic domain and a cell wall binding domain, LysPBC2 has a spore binding domain (SBD) partially overlapping its catalytic domain, which specifically binds to <I>B. cereus</I> spores but not to vegetative cells of <I>B. cereus</I>. Both immunogold electron microscopy and a binding assay indicated that the SBD binds the external region of the spore cortex layer. Several amino acid residues required for catalytic or spore binding activity of LysPBC2 were determined by mutagenesis studies. Interestingly, LysPBC2 derivatives with impaired spore binding activity showed an increased lytic activity against vegetative cells of <I>B. cereus</I> compared with that of wild-type LysPBC2. Further biochemical studies revealed that these LysPBC2 derivatives have lower thermal stability, suggesting a stabilizing role of SBD in LysPBC2 structure.</P><P><B>IMPORTANCE</B> Bacteriophages produce highly evolved lytic enzymes, called endolysins, to lyse peptidoglycan and release their progeny from bacterial cells. Due to their potent lytic activity and specificity, the use of endolysins has gained increasing attention as a natural alternative to antibiotics. Since most endolysins from Gram-positive-bacterium-infecting phages have a modular structure, understanding the function of each domain is crucial to make effective endolysin-based therapeutics. Here, we report the functional and biochemical characterization of a <I>Bacillus cereus</I> phage endolysin, LysPBC2, which has an unusual spore binding domain and a cell wall binding domain. A single point mutation in the spore binding domain greatly enhanced the lytic activity of endolysin at the cost of reduced thermostability. This work contributes to the understanding of the role of each domain in LysPBC2 and will provide insight for the rational design of efficient antimicrobials or diagnostic tools for controlling <I>B. cereus</I>.</P>

훼손 수목 이식에 대한 이해관계자 인식 연구

문윤정 ( Yoonjung Moon ),박홍준 ( Hongjun Park ),차재규 ( Jaegyu Cha ),나진주 ( Jinjoo Na ),이선미 ( Seonmi Lee ) 한국환경영향평가학회 2021 환경영향평가 Vol.30 No.6

환경영향평가 시 개발사업으로 훼손되는 수목의 약 10%를 이식 또는 재활용하도록 하고 있으나, 이식 시 여러 가지 문제점들이 제기되고 있다. 본 연구에서는 이해관계자를 대상으로 이식 시 발생하는 문제점에 대한 인식을 파악하였다. 2020년 10월 9일부터 25일까지 실시한 설문조사에 협의기관, 검토기관, 사업자·대행자 그룹별 각각 36명, 44명, 83명(총 163명)이 참여하였다. 세 그룹 모두 개발사업으로 인한 훼손이 심각하므로 개발 부담금이 증가하더라도 훼손 수목의 일부를 이식하는 것이 필요하다고 응답하였다. 가장 심각하다고 응답한 문제점은 고사율이었다. 고사 시 대체 방안으로 세 그룹 모두 동일한 수종과 수량을 식재해야 한다는 응답 비율이 높았다. 고사율을 줄이기 위해 이식 수목은 크기가 작은 것을 이식하고, 이식 수종은 식재종과 조경 수종을 포함하여 확대시키고, 이식 수목량은 자생 수목량 대비 이식 비율을 산정하자는 응답 비율이 높았다. 관리자를 별도로 배치할 필요가 있다고 응답한 비율도 높았다. 본 설문조사의 결과는 훼손 수목의 이식 시 발생하는 문제점을 개선하기 위한 기초 자료로 활용할 것이다. About 10% of trees damaged by the development projects are to be transplanted when conducting the Environmental Impact Assessment. However, various problems have been raised during transplantation. In this study, we confirm the stakeholder’s perceptions of the problems that occur during transplantation. The survey was conducted from October 9 to 25, 2020. Among the stakeholder groups, 36 respondents participated in the consulting institute group, 44 from the review institute group, and 83 from the developer·agency group (total of 163). All three groups responded that it was necessary to transplant some of the damaged trees even if the development charge increased because the damage caused by the development project was serious. The most serious problem was ‘high mortality’. The response rate was high that all three groups should plant the same species with the same quantity as an alternative method in case of withering. In order to reduce the mortality rate, small-sized trees were transplanted and transplanted trees were expanded to include planted species and landscape trees. In addition, the number of transplanted trees was high in response to calculating the transplant ratio to the number of native tree damaged. The percentage of respondents who said that it was necessary to allocate a separate manager was also high. The results will be used as basic data to improve problems that occur during transplantation of damaged trees.

Analysis of Microbiota in Bellflower Root, Platycodon grandiflorum, Obtained from South Korea

( Daeho Kim ),( Sanghyun Hong ),( Hongjun Na ),( Jihwan Chun ),( Robin B. Guevarra ),( You-tae Kim ),( Sangryeol Ryu ),( Hyeun Bum Kim ),( Ju-hoon Lee ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4

Bellflower root (Platycodon grandiflorum), which belongs to the Campanulaceae family, is a perennial grass that grows naturally in Korea, northeastern China, and Japan. Bellflower is widely consumed as both food and medicine owing to its high nutritional value and potential therapeutic effects. Since foodborne disease outbreaks often come from vegetables, understanding the public health risk of microorganisms on fresh vegetables is pivotal to predict and prevent foodborne disease outbreaks. We investigated the microbial communities on the bellflower root (n = 10). 16S rRNA gene amplicon sequencing targeting the V6-V9 regions of 16S rRNA genes was conducted via the 454-Titanium platform. The sequence quality was checked and phylogenetic assessments were performed using the RDP classifier implemented in QIIME with a bootstrap cutoff of 80%. Principal coordinate analysis was performed using the weighted Fast UniFrac distance. The average number of sequence reads generated per sample was 67,192 sequences. At the phylum level, bacterial communities from the bellflower root were composed primarily of Proteobacteria, Firmicutes, and Actinobacteria in March and September samples. Genera Serratia, Pseudomonas, and Pantoea comprised more than 54% of the total bellflower root bacteria. Principal coordinate analysis plots demonstrated that the microbial community of bellflower root in March samples was different from those in September samples. Potential pathogenic genera, such as Pantoea, were detected in bellflower root samples. Even though further studies will be required to determine if these species are associated with foodborne illness, our results indicate that the 16S rRNA gene-based sequencing approach can be used to detect pathogenic bacteria on fresh vegetables.