• Journal of Microbiology and Biotechnology
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• 제34권6호
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• pp.1189-1196
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• 2024

Bacterial resistance to commonly used antibiotics is one of the major challenges to be solved today. Bacteriophage endolysins (Lysins) have become a hot research topic as a new class of antibacterial agents. They have promising applications in bacterial infection prevention and control in multiple fields, such as livestock and poultry farming, food safety, clinical medicine and pathogen detection. However, many phage endolysins display low bactericidal activities, short half-life and narrow lytic spectrums. Therefore, some methods have been used to improve the enzyme properties (bactericidal activity, lysis spectrum, stability and targeting the substrate, etc) of bacteriophage endolysins, including deletion or addition of domains, DNA mutagenesis, chimerization of domains, fusion to the membrane-penetrating peptides, fusion with domains targeting outer membrane transport systems, encapsulation, the usage of outer membrane permeabilizers. In this review, research progress on the strategies for improving their enzyme properties are systematically presented, with a view to provide references for the development of lysins with excellent performances.

• Biomolecules & Therapeutics
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• 제1권2호
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• pp.196-203
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• 1993

We compared in vitro antibacterial activity of DWC-751, a new parenteral cephalosporin antibiotic, with those of cefpirome (CPR), cefotaxime (CTX) and ceftazidime (CAZ). DWC-751 showed a broad antimicrobial spectrum against Gram-positive and negative bacteria. The antibacterial activity of DWC-751 against Stapylococcus aureus was equal to that of CPR and superior to those of CTX and CAZ. The activity of it against Excherichia coli was more potent than those of CPR, CTX and CAZ. Against Pseudomonas aeruginosa, DWC-751 was slightly inferior to that of CAZ and superior to those of CPR and CTX. The antibacterial activity of DWC-751 was superior to those of CPR, CTX and CAZ against clinical isolates and ofloxacin resistant strains. DWC-751 showed bactericidal action against Escherichia coli at concentrations close to the MIC and induced the formation of filament and burge and lysis of Escherichia coli in a microscopic examination.

• BMB Reports
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• 제45권7호
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• pp.408-413
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• 2012

Almost all melanoma cells express at least one member of the MAGE-A antigen family, making the cytotoxic T cells (CTLs) epitopes with cross-immunizing potential in this family attractive candidates for the broad spectrum of anti-melanoma immunotherapy. In this study, four highly homologous peptides (P264: FLWGPRALA, P264I9: FLWGPRALI, P264V9: FLWGPRALV, and P264H8: FLWGPRAHA) from the MAGE-A antigens were selected by homologous alignment. All four peptides showed high binding affinity and stability to HLA-A$^*02:01$ molecules, and could prime CTL immune responses in human PBMCs and in HLA-A$^*02:01/K^b$ transgenic mice. CTLs elicited by the four epitope peptides could cross-lyse tumor cells expressing the mutual target antigens, except MAGE-A11 which was not tested. However, CTLs induced by P264V9 and P264I9 showed the strongest target cell lysis capabilities, suggesting both peptides may represent the common CTL epitopes shared by the eight MAGE-A antigens, which could induce more potent and broad-spectrum antitumor responses in immunotherapy.

• 한국토양비료학회지
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• 제48권5호
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• pp.485-491
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• 2015

This study was performed to investigate thermophilic bacteria from soil having broad antifungal spectrum against Rhizoctonia solani, Colletotrichum gloeosporioides, Phytophthora capsici, Fusarium oxysporum f.sp. lycopersici, and Botrytis cinerea. One isolate selected could resist heat shock of $60^{\circ}C$ for one hour, and had broad antifungal activity in dual culture assay against all tested fungal pathogens and was identified as Bacillus amyloliquefaciens Y1 using 16S rRNA gene sequence. Further investigation for antifungal activity of bacterial culture filtrate (BCF) and butanol crude extract (BCE) of various concentrations showed broad spectrum antifungal activity and fungal growth inhibition significantly increased with increasing concentration with highest growth inhibition of 100% against R. solani with 50% BCF and 11 mm of zone of inhibition against R. solani with 4 mg BCE concentration. Treatment of butanol crude extract resulted in deformation, lysis or degradation of C. gloeosporioides and P. capsici hyphae. Furthermore, B. amyloliquefaciens Y1 produced volatile compounds inhibiting growth of R. solani (70%), C. gloeosporioides (65%) and P. capsici (65-70%) when tested in volatile assay. The results from the study suggest that B. amyloliquefaciens Y1 could be a biocontrol candidate to control fungal diseases in crops.

• ALGAE
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• 제38권1호
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• pp.39-55
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• 2023

Exploring mixotrophy of dinoflagellate species is critical to understanding red-tide dynamics and dinoflagellate evolution. Some species in the dinoflagellate genus Karenia have caused harmful algal blooms. Among 10 Karenia species, the mixotrophic ability of only two species, Karenia mikimotoi and Karenia brevis, has been investigated. These species have been revealed to be mixotrophic; however, the mixotrophy of the other species should be explored. Moreover, although K. mikimotoi was previously known to be mixotrophic, only a few potential prey species have been tested. We explored the mixotrophic ability of Karenia bicuneiformis, Karenia papilionacea, and Karenia selliformis and the prey spectrum of K. mikimotoi by incubating them with 16 potential prey species, including a cyanobacterium, diatom, prymnesiophyte, prasinophyte, raphidophyte, cryptophytes, and dinoflagellates. Cells of K. bicuneiformis, K. papilionacea, and K. selliformis did not feed on any tested potential prey species, indicating a lack of mixotrophy. The present study newly discovered that K. mikimotoi was able to feed on the common cryptophyte Teleaulax amphioxeia. The phylogenetic tree based on the large subunit ribosomal DNA showed that the mixotrophic species K. mikimotoi and K. brevis belonged to the same clade, but K. bicuneiformis, K. papilionacea, and K. selliformis were divided into different clades. Therefore, the presence or lack of a mixotrophic ability in this genus may be partially related to genetic characterizations. The results of this study suggest that Karenia species are not all mixotrophic, varying from the results of previous studies.

• Journal of Microbiology and Biotechnology
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• 제30권10호
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• pp.1552-1558
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• 2020

With an increase in the consumption of non-heated fresh food, foodborne shiga toxin-producing Escherichia coli (STEC) has emerged as one of the most problematic pathogens worldwide. Endolysin, a bacteriophage-derived lysis protein, is able to lyse the target bacteria without any special resistance, and thus has been garnering interest as a powerful antimicrobial agent. In this study, rV5-like phage endolysin targeting E. coli O157:H7, named as LysECP26, was identified and purified. This endolysin had a lysozyme-like catalytic domain, but differed markedly from the sequence of lambda phage endolysin. LysECP26 exhibited strong activity with a broad lytic spectrum against various gram-negative strains (29/29) and was relatively stable at a broad temperature range (4℃-55℃). The optimum temperature and pH ranges of LysECP26 were identified at 37℃-42℃ and pH 7-8, respectively. NaCl supplementation did not affect the lytic activity. Although LysECP26 was limited in that it could not pass the outer membrane, E. coli O157: H7 could be effectively controlled by adding ethylenediaminetetraacetic acid (EDTA) and citric acid (1.44 and 1.14 log CFU/ml) within 30 min. Therefore, LysECP26 may serve as an effective biocontrol agent for gram-negative pathogens, including E. coli O157:H7.

• Fisheries and Aquatic Sciences
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• 제16권2호
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• pp.79-84
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• 2013

In an effort to discover an alternative antibiotic for treating infections with methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas sp. UJ-6, a marine bacterium that exhibited antibacterial activity against MRSA, was isolated. The culture broth and its ethyl acetate extract exhibited bactericidal activity against MRSA. The extract also exhibited antibacterial activity against gram-negative bacteria, which were not susceptible to vancomycin. The treatment of MRSA with the extract resulted in abnormal cell lysis. The extract retained >95% of its anti-MRSA activity after heat treatment for 15 min at $121^{\circ}C$. Thus, although most antibiotics are unstable under conditions of thermal stress, Pseudomonas sp. UJ-6 produces a heat-stable anti-MRSA substance. The results of this study strongly suggest that Pseudomonas sp. UJ-6 can be used to develop a novel, heat-stable, broad-spectrum antibiotic for the treatment of MRSA infections.

• Journal of Microbiology and Biotechnology
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• 제28권10호
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• pp.1654-1663
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• 2018

Finding a safe and broad-spectrum medication is a goal of scientists, pharmacists, and physicians, but developing and fabricating the right medicine can be challenging. The current study describes the formation of silver nanoparticles (AgNPs) by Fusarium mangiferae. It involves the antibiofilm activity of the nanoparticles against Staphylococcus aureus. It also involves cytotoxic effect against mammalian cell lines. Well-dispersed nanoparticles are formed by F. mangiferae. The sizes of the nanoparticles were found to range from 25 to 52 nm, and UV-Vis scan showed absorption around 416-420 nm. SEM, TEM, and AFM results displayed spherical and oval shapes. Furthermore, the FTIR histogram detected amide I and amide II compounds responsible for the stability of AgNPs in an aqueous solution. AgNPs were observed to decrease the formation of biofilm at 75% (v/v). DNA reducing, smearing, and perhaps fragmentation were noticed after treating the bacterial cells with 50% (v/v). Additionally, cell lysis was detected releasing proteins in the supernatant. It was also observed that the AgNPs have the ability to cause 59% cervical cancer cell line (HeLa) deaths at 25% (v/v), however, they showed about 31% toxicity against rat embryo fibroblast transformed cell lines (REF). The results of this study prove the efficiency of AgNPs as an antibiofilm against S. aureus, suggesting that AgNPs could be an alternative to antibiotics. It must also be emphasized that AgNPs displayed cytotoxic behavior against mammalian cell lines. Further studies are needed for assessing risk in relation to the possible benefit of prescribing AgNPs.

• 생명과학회지
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• 제13권1호
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• pp.90-98
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• 2003

대파 흑색썩음균핵병균 (Sclerotium cepivorum)에 길항력을 가진 Serratia plymuthica L-1의 길항 메카니즘을 조사한기 위해 S. plymuthica L-1이 생산하는 세포외 chitinase를 정제하여 그 특성을 조사하였다. Colloidal chitin이 함유된 배지에서 생산된 S. plymuthica L-1 chitinase는 $(NH_4)_2$$_2$$SO_2$ 40~70% precipitation, affinity adsorption, DEAE-sephadex A-50 column chromatography 및 sephadex G-200 column filtration 과정을 통하여 정제하였다. 정제된 chitinase는 7.3% 회수율과 19.8의 정제도를 나타내었으며, 전기영동시 단일밴드를 얻었으며, 분자량은 55kDa로 나타났다. 정제된 chitinase의 최적 pH 및 온도는 5.5, $55^{\circ}C$이었고, 온도안정성 조사에서 정제효소는 $50^{\circ}C$까지 90%의 잔존활성을 유지하였으나 $60^{\circ}C$이상에서는 급격하게 효소활성이 실활되었다. $Ca^{2+}$, $Mn^{2+}$, $Mg^{2+}$ 등의 이온은 대략 20군 이상의 효소를 활성화시켰으나 $Cu^{2+}$이온은 약 80%의 효소활성을 억제시켰고, SDS, p-CMB, MIA 등도 효소활성을 저해하는 작용을 하였으며, colloidal chitin에 대한 Km값은 3.26 mg/$m\ell$로 나타났다. 정제효소에 의한 각종 병원균에 대한 생육 억제정도는 흑색썩음균핵병균, 고추 검은무의병균, 고추 탄저병균, 도라지 줄기마름병균, 고추 흰별무늬병균, 오이 균핵병균, 수박 덩굴쪼김병균 등에는 길항력을 나타내었으나 고추 역병균과 무 모잘록병균에서는 길항력이 아주 낮게 나타났다. 정제 chitinase에 의해 대파 흑색썩음균핵병 S.. cepivorum의 균사는 팽창과 균사 끝의 용균, 분해 및 변색현상을 관찰할 수 있었고 chitinase 기능과 Iysozyme 기능을 모두 가지고 있을 것으로 추정된다.

• 한국식품저장유통학회지
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• 제13권5호
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• pp.629-633
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• 2006

리기다소나무 잎추출물의 항균력을 조사한 결과, $100{\sim}250{\mu}g/mL$ 이상의 농도에서 뚜렷한 항균활성을 보였고, 광역의 병원성 및 부패성 미생물들에 대하여 항균활성을 나타내었다. 특히, 리기다소나무 알코올 추출물에서는 $100{\mu}g/mL$의 낮은 처리농도에서도 뚜렷한 항균력을 나타내었다. 또한 추출물의 농도가 증가함에 따라 미생물의 생육저해환의 직경도 커졌으며, 알코올추출물에서 좀 더 뚜렷한 항균력을 관찰할 수 있었다. 또한, 리기다소나무 잎추출물은 넓은 범위의 열 및 pH에서 안정성을 나타냈다. 따라서 리기다소나무 잎추출물의 항균물질은 항균활성이 높고, 항균 spectrum이 광범위 할뿐 아니라, 넓은 범위의 온도 및 pH에 안정하여 이상적인 천연 항균제로서의 개발가능성을 제시하였다. 아울러, 리기다소나무 잎추출물의 주요 항균작용기작은 미생물 세포막의 perturbation 기능에 기인한 것으로 사료되었다. 또한, fomalin 투여후 PRLE처리로 혈청내 formaldehyde의 분해가 촉진되어 제거비율이 증진되는 효과를 보였으며, formalin 투여로 인한 생체내 hemoglobin 생성비율도 짧은 시간내에 회복됨을 예측할 수 있었다.