期刊文献+
共找到21篇文章
< 1 2 >
每页显示 20 50 100
Redox control of magnetosome biomineralization 被引量:2
1
作者 Yingjie LI 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第6期2070-2081,共12页
Magnetotactic bacteria can orientate in the Earth’s magnetic field to search for their preferred microoxic environments,which is achieved by their unique organelles,the magnetosomes.Magnetosomes contain nanometer-siz... Magnetotactic bacteria can orientate in the Earth’s magnetic field to search for their preferred microoxic environments,which is achieved by their unique organelles,the magnetosomes.Magnetosomes contain nanometer-sized crystal particles of magnetic iron minerals,which are only synthesized in lowoxygen environments.Although the mechanism of aerobic repression for magnetosome biomineralization has not yet fully understood,a series of studies have verified that redox modulation is pivotal for magnetosome formation.In this review,these advances in redox modulation for magnetosome biosynthesis are highlighted,mainly including respiration pathway enzymes,specific magnetosome-associated redox proteins,and oxygen-or nitrate-sensing regulators.Furthermore,their relationship during magnetosome biomineralization is discussed to give insight into redox control and biomineralization and inspire potential solutions for the application of respiration pathways to improve the yields of magnetosome. 展开更多
关键词 magnetotactic bacteria magnetosome BIOMINERALIZATION RESPIRATION redox control
下载PDF
MamZ protein plays an essential role in magnetosome maturation process of Magnetospirillum gryphiswaldense MSR-1 被引量:1
2
作者 Sha WU Qing WANG +5 位作者 Xu WANG Ruixue GUO Tongwei ZHANG Yongxin PAN Feng LI Ying LI 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第6期2082-2096,共15页
Based on analysis of gene structure of mamXY operon in Magnetospirillum gryphiswaldense strain MSR-1,we constructed a mamZ deletion mutant strain(ΔmamZ)and four complemented strains with different mamZ fragment lengt... Based on analysis of gene structure of mamXY operon in Magnetospirillum gryphiswaldense strain MSR-1,we constructed a mamZ deletion mutant strain(ΔmamZ)and four complemented strains with different mamZ fragment lengths.Various cell phenotypic and physiological parameters were evaluated and compared among the wild-type(WT),mutant,and complemented strains.Cell growth rates were not notably different;however,magnetic response(Cmag)and iron uptake ability were significantly lower inΔmamZ.High-resolution transmission electron microscopy(HR-TEM)showed that magnetosomes inΔmamZ were small and irregular,and rock magnetic measurements suggested that they contained immature particles.In comparison to WT of MSR-1,intracellular iron content ofΔmamZ and the complemented strains cultured with 20mmol/L iron source was similar or slightly higher.The complemented strains were unable to synthesize mature or normal amounts of magnetosomes,apparently because of abnormal expression of the transmembrane domain of MamZ protein.Real-time reverse transcription polymerase chain reaction(RTqPCR)analysis showed that relative transcription levels of mamX and ftsZ-like genes inΔmamZ were higher at 18 h than at 12 h,suggesting that MamXY proteins play cooperative functional roles in the magnetosome maturation process.Transcription level of mms6 was significantly upregulated inΔmamZ(incubated at 12 h)and the complemented strains(incubated at 12 and 18 h),refl ecting possible interaction between MamXY and Mms6 proteins during magnetosome biosynthesis.These findings,taken together,demonstrate the essential role of MamZ in the magnetosome maturation process in MSR-1. 展开更多
关键词 Magnetospirillum gryphiswaldense mamZ deletion mamXY operon magnetosome maturation
下载PDF
Biomedical applications of magnetosomes: State of the art and perspectives 被引量:1
3
作者 Gang Ren Xia Zhou +5 位作者 Ruimin Long Maobin Xie Ranjith Kumar Kankala Shibin Wang Yu Shrike Zhang Yuangang Liu 《Bioactive Materials》 SCIE CSCD 2023年第10期27-49,共23页
Magnetosomes, synthesized by magnetotactic bacteria (MTB), have been used in nano- and biotechnological applications, owing to their unique properties such as superparamagnetism, uniform size distribution, excellent b... Magnetosomes, synthesized by magnetotactic bacteria (MTB), have been used in nano- and biotechnological applications, owing to their unique properties such as superparamagnetism, uniform size distribution, excellent bioavailability, and easily modifiable functional groups. In this review, we first discuss the mechanisms of magnetosome formation and describe various modification methods. Subsequently, we focus on presenting the biomedical advancements of bacterial magnetosomes in biomedical imaging, drug delivery, anticancer therapy, biosensor. Finally, we discuss future applications and challenges. This review summarizes the application of magnetosomes in the biomedical field, highlighting the latest advancements and exploring the future development of magnetosomes. 展开更多
关键词 magnetosome Bionic magnetosomes Magnetotactic bacteria Modification strategies Biomedical applications
原文传递
Distribution of magnetotactic bacteria in China and characterization of magnetosomes 被引量:3
4
作者 范国昌 李荣森 +2 位作者 李小刚 高梅影 贾蓉芬 《Chinese Science Bulletin》 SCIE EI CAS 1996年第11期944-948,共5页
Magnetotactic bacteria (MB), first discovered by Blakemore in 1975, have been con-stantly found in ponds, rivers, marine and damp grasslands. They all appear to beGram-negative (G^-), polar or tuft flagella, microaero... Magnetotactic bacteria (MB), first discovered by Blakemore in 1975, have been con-stantly found in ponds, rivers, marine and damp grasslands. They all appear to beGram-negative (G^-), polar or tuft flagella, microaerophilic and morphologically diverse(coccus, bacillus, spirillum and vibrio) . In the northern hemisphere, these bacteriaorient northward and will swim towards the geomagnetic south pole. The reverse istrue of those in the southern hemisphere. At the geomagnetic equator, both 展开更多
关键词 magnetotactic BACTERIA DISTRIBUTION magnetosomes.
下载PDF
Cloning and functional analysis of the sequences flanking mini-Tn5 in the magnetosomes deleted mutant NM4 of Magnetospirillum gryphiswaldense MSR-1 被引量:2
5
作者 LI Feng1,2, LI Ying1, JIANG Wei1, WANG Zhenfang1 & LI Jilun1 1. State Key Laboratory for Agro-biotechnology and Department of Microbiology, China Agricultural University, Beijing 100094, China 2. Department of Biology, Huaibei Coal Industry Teachers’ College, Huaibei 235000, China 《Science China(Life Sciences)》 SCIE CAS 2005年第6期574-584,共11页
A magnetosome deleted mutant NM4 of Magnetospirillum gryphiswaldense MSR-1 was generated by mini-Tn5 transposon mutagenesis, and a 5045-bp fragment flanking mini-Tn5 in NM4 was cloned by Anchored PCR. Sequencing analy... A magnetosome deleted mutant NM4 of Magnetospirillum gryphiswaldense MSR-1 was generated by mini-Tn5 transposon mutagenesis, and a 5045-bp fragment flanking mini-Tn5 in NM4 was cloned by Anchored PCR. Sequencing analysis showed that this fragment involved six putative open reading frames (ORFs); the mini-Tn5 was inserted into ORF4. Functional complementary test indicated that the 5045-bp fragment was required for biosynthesis of mag-netosomes in M. gryphiswaldense MSR-1. The protein encoded by ORF4 had 25% of identity with the chemotaxis protein CheYIII of Caulobacter crescentus CB15, and the protein encoded by ORF4 contained a conserved signal receiver domain that can receive the signal from the sensor partner of the bacterial two-component systems. It was suggested that the protein en-coded by ORF4 may take part in the signal transduction relating to biosynthesis of magneto-somes. 展开更多
关键词 MAGNETOSPIRILLUM gryphiswaldense magnetosome deleted mutant gene cloning functional analysis.
原文传递
Paleo-environmental study on the growth of magnetotactic bacteria and precipitation of magnetosomes in Chinese loess-paleosol sequences 被引量:2
6
作者 PENG Xianzhi JIA Rongfen +2 位作者 LI Rongsen DAI Shunying LIU Tungsheng 《Chinese Science Bulletin》 SCIE EI CAS 2000年第S1期21-25,共5页
405 samples were collected from L5-S5-L6 in consideration of obvious variations in susceptibility of the geological sections, which are section Xifeng in Gansu Province and section Duanjiapo in Shaanxi Province for st... 405 samples were collected from L5-S5-L6 in consideration of obvious variations in susceptibility of the geological sections, which are section Xifeng in Gansu Province and section Duanjiapo in Shaanxi Province for study of magnetotactic bacteria (MB) and magnetosomes (MS) in Chinese loess-paleosol sequences. MB in each sample were observed by TEM after being cultured under 8-18℃, room temperature (RT), 25℃, 26℃ and 30℃ conditions. In general, MB are distributed widely in loess-paleosol sequences, fewer in loess layers with predomination of vibriod in shape. However, there are more MB in paleosol layers with morphological varieties such as roddish, vibriod and occasionally approximately coccus. The magnetosomes (MS) in MB of paleosol are usually arranged in chains along the cells. It was also found that MB growth and MS formation are associated with the environment in which MB live. It can be inferred from the distributions of MB and MS that the paleoclimates fluctuated during the formation of 展开更多
关键词 LOESS-PALEOSOL SEQUENCES magnetotactic BACTERIA (MB) magnetosomeS (MS) paleoeclimate SECTION Xifeng SECTION Duanjiapo.
下载PDF
occurrence and microscopic analyses of multicellular magnetotactic prokaryotes from coastal sediments in the Yellow Sea 被引量:5
7
作者 周克 潘红苗 +3 位作者 张圣妲 岳海东 肖天 吴龙飞 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2011年第2期246-251,共6页
Multicellular magnetotactic prokaryotes (MMPs) are a group of aggregates composed of 7-45 gram-negative cells synthesizing intracellular magnetic crystals. Although they are thought to be globally distributed, MMPs ... Multicellular magnetotactic prokaryotes (MMPs) are a group of aggregates composed of 7-45 gram-negative cells synthesizing intracellular magnetic crystals. Although they are thought to be globally distributed, MMPs have been observed only in marine environments in America and Europe. Most MMPs share a rosette-like morphology and biomineralize iron sulfide crystals. In the present study, abundant MMPs were observed, with a density of 26 ind./cm^3, in the sediments of a coastal lagoon, Lake Yuehu, in the Yellow Sea. Optical microscopy showed that all of them were rosette shaped with a diameter of 5.5±0.8 μm. Transmission electron microscopy revealed that these MMPs were composed of 10- 16 ovoid cells and flagellated peritrichously. High-resolution transmission electron microscopy and energy dispersive X-ray analysis indicated that they biomineralized bullet-shaped magnetite crystals in highly organized parallel chains within which the magnetosomes were oriented in the same direction. This is the first report of MMPs from Asia and demonstrates the ubiquitous distribution of MMPs. 展开更多
关键词 multicellular magnetotactic prokaryotes rosette-like magnetosomeS MAGNETITE Yellow Sea
原文传递
Characterization of Mediterranean Magnetotactic Bacteria 被引量:2
8
作者 Lefevre Christopher Bemadac Alain +7 位作者 Pradel Nathalie WU Longfei Yu-Zhang Kui XIAO Tian Yonnet Jean-Paul Lebouc Afef SONG Tao Fukumori Yoshihiro 《Journal of Ocean University of China》 SCIE CAS 2007年第4期355-359,共5页
Magnetotactic bacteria are a diverse group of motile prokaryotes that are ubiquitous in aquatic habitats and cosmopolitan in distribution. In this study, we collected magnetotactic bacteria from the Mediterranean Sea.... Magnetotactic bacteria are a diverse group of motile prokaryotes that are ubiquitous in aquatic habitats and cosmopolitan in distribution. In this study, we collected magnetotactic bacteria from the Mediterranean Sea. A remarkable diversity of morphotypes was observed, including multicellular types that seemed to differ from those previously found in North and South America. Another interesting organism was one with magnetosomes arranged in a six-stranded bundle which occupied one third of the cell width. The magnetosome bundle was evident even under optic microscopy. These cells were connected together and swam as a linear entire unit. Magnetosomes did not always align up to form a straight linear chain. A chain composed of rectangle magnetosomes bent at a posi- tion with an oval crystal. High resolution transmission electron microscopy analysis of the crystal at the pivotal position suggested uncompleted formation of the crystal. This is the first report of Mediterranean magnetotactic bacteria, which should be useful for studies of biogeochemical cycling and geohistory of the Mediterranean Sea. 展开更多
关键词 Magnetotactic bacteria Mediterranean Sea GEOMAGNETISM biogeochemical cycling ECOLOGY magnetosome crystals
下载PDF
Observations on a magnetotactic bacteria-grazing ciliate in sediment from the intertidal zone of Huiquan Bay,China 被引量:1
9
作者 Si CHEN Kaixuan CUI +5 位作者 Wenyan ZHANG Yicong ZHAO Tian XIAO Hongmiao PAN Wuchang ZHANG Long-Fei WU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第6期2053-2062,共10页
Magnetotactic bacteria(MTB)are a group of prokaryotes having the ability to orient and swim along geomagnetic field lines because they contain intracellular magnetosomes that are synthesized through a biomineralizatio... Magnetotactic bacteria(MTB)are a group of prokaryotes having the ability to orient and swim along geomagnetic field lines because they contain intracellular magnetosomes that are synthesized through a biomineralization process.Magnetosomes have recently also been found in unicellular eukaryotes,which are referred to as magnetically responsive protists(MRPs).The magnetosomes have three origins in MRPs.In this study,we characterized a MTB-grazing ciliated MRP that was magnetically collected from intertidal sediment of Huiquan Bay,Qingdao,China.Based on 18S rRNA gene sequence analysis,the ciliated MRP was tentatively identified as Uronemella parafi lificum HQ.Using transmission electron microscopy,we observed that magnetosomes having 2-3 shapes were randomly distributed within this ciliate.Energydispersive X-ray spectroscopy and high-resolution transmission electron microscopy images of the magnetosomes were consistent with them being composed of magnetite.Magnetosomes having the same shape and mineral composition were also detected in MTB that occurred in the same environment as the ciliated MRP.Statistical analysis showed that the size and shape of the magnetosomes in the ciliated MRP were similar to those in MTB.The results suggest that this ciliated MRP can graze,ingest,and digest various types of MTB.It is certainly worth noting that this is the first record of MRPs in Asian aquatic sediment and suggesting they might be widely distributed.These results also support the assertion that MRPs probably contribute to the ecological cycles of iron,and expand possibilities for research into the mechanism of magnetoreception in eukaryotes. 展开更多
关键词 magnetically responsive protist CILIATE magnetotactic bacteria magnetosome graze MAGNETORECEPTION
下载PDF
Characterization and diversity of magnetotactic bacteria from sediments of Caroline Seamount in the Western Pacific Ocean 被引量:1
10
作者 Kaixuan CUI Wenyan ZHANG +6 位作者 Jia LIU Cong XU Yicong ZHAO Si CHEN Hongmiao PAN Tian XIAO Long-Fei WU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第6期2027-2043,共17页
Magnetotactic bacteria(MTB)are a group of microorganisms capable of orientating and swimming along magnetic fields because they contain intracellular biomineralized magnetosomes composed of magnetite(Fe 3 O 4)or/and g... Magnetotactic bacteria(MTB)are a group of microorganisms capable of orientating and swimming along magnetic fields because they contain intracellular biomineralized magnetosomes composed of magnetite(Fe 3 O 4)or/and greigite(Fe_(3)S_(4)).They are ubiquitous in freshwater,brackish,and marine habitats,and are cosmopolitan in distribution.However,knowledge of their occurrence and distribution in seamount ecosystems is limited.We investigated the diversity and distribution of MTB in the Caroline Seamount(CM4).The abundance of living MTB in 12 stations in depth varying from 90 to 1545 m was 1.1×10^(3)-43.7×10^(3) inds./dm 3.Despite diverse shapes of MTB observed,magnetotactic cocci were the dominant morphotype and could be categorized into two types:1)typical cocci that appeared to have peritrichous fl agella;and 2)those characterized by having a drop-shaped form and one bundle of fl agella located at the thin/narrow end of the cell.Transmission electron microscopy(TEM)analysis revealed that the magnetosomes formed by those magnetotactic cocci are magnetite(Fe 3 O 4)with octahedral crystal habit.A total of 41 operational taxonomic units(OTUs)of putative MTB(2702 reads)were acquired from nine stations,based on high-throughput sequencing.Of these,40 OTUs belonged to the Proteobacteria phylum and one belonged to the Nitrospirae phylum.We found apparent connectivity between the MTB populations on the Caroline and Kexue(Science in Chinese)seamounts,although the diversity of MTB on Caroline was much richer than on the Kexue Seamount.Our results imply that the unique topography of seamounts and other as-yet unclear environmental factors could lead to evolution of different fl agella arrangements in magnetotactic cocci,and the occurrence of octahedral magnetite magnetosomes. 展开更多
关键词 magnetotactic bacteria Caroline Seamount ABUNDANCE DIVERSITY magnetosome
下载PDF
Characterization of uncultivated magnetotactic bacteria from the sediments of Yuehu Lake, China 被引量:4
11
作者 DU Haijian ZHANG Rui +6 位作者 ZHANG Wenyan XU Cong CHEN Yiran PAN Hongmiao ZHOU Ke WU Long-fei XIAO Tian 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2017年第2期94-104,共11页
Marine magnetotactic bacteria were collected from the intertidal sediments of Yuehu Lake(China), where their abundance reached 103–104 ind./cm3. Diverse morphotypes of magnetotactic bacteria were observed, includin... Marine magnetotactic bacteria were collected from the intertidal sediments of Yuehu Lake(China), where their abundance reached 103–104 ind./cm3. Diverse morphotypes of magnetotactic bacteria were observed, including cocci and oval, vibrio-, spirillum-, rod-, elliptical-, handle- and bar-shaped forms. The magnetococci were the most abundant, and had flagella arranged in parallel within a bundle. The majority of magnetosomes were arranged in one, two or multiple chains, although irregular arrangements were also evident. All the results of high-resolution transmission electron microscopy(HRTEM) analysis show that magnetosome crystals were composed of Fe3O4, and their morphology was specific to particular cell morphotypes. By the 16 S r RNA gene sequence analysis, we found fourteen operational taxonomic units(OTUs) which were related to magnetotactic bacteria. Among these, thirteen belonged to the Alphaproteobacteria and one to the Gammaproteobacteria.Compared with known axenic and uncultured marine magnetotactic bacteria, the 16 S r RNA gene sequences of most magnetotactic bacteria collected from the Yuehu Lake exhibited sequence identities ranging from 90.1% to96.2%(〈97%). The results indicate that microbial communities containing previously unidentified magnetotactic bacteria occur in the Yuehu Lake. 展开更多
关键词 magnetotactic bacteria magnetosome biodiversity Yuehu Lake intertidal sediments
下载PDF
Release the iron: does the infection of magnetotactic bacteria by phages play a role in making iron available in aquatic environments? 被引量:1
12
作者 Igor TAVEIRA Dennis ABAZYLINSKI Fernanda ABREU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第6期2063-2069,共7页
Magnetotactic bacteria(MTB)are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes’biomineralization within the cell.These structures are ferrimagnetic organelles that impart a magnetic ... Magnetotactic bacteria(MTB)are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes’biomineralization within the cell.These structures are ferrimagnetic organelles that impart a magnetic moment to the cell.To succeed in producing magnetosomes,MTB accumulate iron in(i)cytoplasm;(ⅱ)magnetosomes;and(ⅲ)nearby the organelle.It has already been estimated that a single MTB has an iron content of 10 to 100-fold higher than Escherichia coli.Phages are the most abundant entity in oceans and are known for controlling nutrient flow such as carbon and nitrogen by viral shunt and pump.The current work addresses the putative role of phages that infect MTB on the iron biogeochemical cycle.Can phage infection in MTB hosts cause a biogenic iron fertilization-like event in localized microenvironments?Are phages critical players in driving magnetosome biomineralization genes(BGs)horizontal transfer?Further investigation of those events,including frequency of occurrence,is necessary to fully comprehend MTB’s effect on iron cycling in aqueous environments. 展开更多
关键词 horizontal gene transfer iron biogeochemical cycle magnetotactic bacteria magnetosome biomineralization genes PHAGES
下载PDF
Morphological and phylogenetic diversity of magnetotactic bacteria and multicellular magnetotactic prokaryotes from a mangrove ecosystem in the Sanya River,South China 被引量:1
13
作者 Haitao CHEN Jinhua LI +1 位作者 Long-Fei WU Wei-Jia ZHANG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第6期2015-2026,共12页
Magnetotactic bacteria(MTB)are morphologically and phylogenetically diverse prokaryotes commonly able to produce magnetic nanocrystals within intracellular membrane-bound organelles(i.e.,magnetosomes)and to swim along... Magnetotactic bacteria(MTB)are morphologically and phylogenetically diverse prokaryotes commonly able to produce magnetic nanocrystals within intracellular membrane-bound organelles(i.e.,magnetosomes)and to swim along geomagnetic field lines.We studied the diversity of MTB in the samples collected from a mangrove area in the Sanya River,Hainan,South China,using microscopic and microbial phylogenetic methods.Results of microanalysis and observation in microscopy and energy dispersive X-ray spectroscopy(EDXS)reveal a highly morphological diversity of MTB including unicellular cocci,vibrios,rod-shaped bacteria,and three morphotypes of multicellular magnetotactic prokaryotes(MMPs).In addition,analysis of the 16S rRNA gene showed that these MTB were clustered into 16 operational taxonomic units affi liated to the Alpha-,Delta-,and Gamma-proteobacteria classes within the Proteobacteria phylum.Meanwhile,by using the coupled fluorescence and transmission electron microscopy analysis,rodshaped bacteria,vibrio,and cocci were phylogenetically and structurally identified at the single-cell level.This study demonstrated highly diverse MTB communities in the mangrove ecosystem and provide a new insight into the overall diversity of MTB. 展开更多
关键词 magnetotactic bacteria diversity magnetosome phylogenetic analysis coordinated fl uorescence in-situ hybridization transmission electron microscopy(FISH-TEM) MANGROVE
下载PDF
Extraction and purification of magnetic nanoparticles from strain of Leptospirillum ferriphilum
14
作者 高健 谢建平 +3 位作者 丁建南 康健 程海娜 邱冠周 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2006年第6期1417-1420,共4页
The magnetic nanoparticles were extracted from Leptospirillum ferriphilum,strain YSK,isolated from acid mine drainages by treatment with sodium dodecyl sulfate(SDS)and centrifugation through a sucrose density gradient... The magnetic nanoparticles were extracted from Leptospirillum ferriphilum,strain YSK,isolated from acid mine drainages by treatment with sodium dodecyl sulfate(SDS)and centrifugation through a sucrose density gradient.Transmission electron microscopy(TEM)indicates that the nanoparticles are approximately spherical with a mean diameter of 44 nm,and magnetite crystals in this size range are single magnetic domains.Energy-dispersive X-ray analysis shows that the nanoparticles primarily contain two kinds of elements,iron and oxygen.Thus it can be concluded that the magnetic particles are magnetosomes.Generally,it is thought that cellular magnetotaxis is a direct consequence of the cell possessing magnetosomes.The discovery of magnetosomes in strain YSK can provide the theoretical basis for screening efficient bioleaching bacteria which are specific to different magnetic minerals under an outer magnetic field. 展开更多
关键词 LEPTOSPIRILLUM ferriphilum STRAIN YSK SDS SUCROSE density GRADIENT magnetosomeS magnetotaxis
下载PDF
Isolation and biological characteristics of aerobic marine magnetotactic bacterium YSC-1
15
作者 高峻 潘红苗 +5 位作者 岳海东 宋涛 赵勇 陈冠军 吴龙飞 肖天 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2006年第4期358-363,共6页
Magnetotactic bacteria have become a hot spot of research in microbiology attracting inten-sive interest of researchers in multiple disciplinary fields. However, the studies were limited in few fas-tidious bacteria. T... Magnetotactic bacteria have become a hot spot of research in microbiology attracting inten-sive interest of researchers in multiple disciplinary fields. However, the studies were limited in few fas-tidious bacteria. The objective of this study aims at isolating new marine magnetic bacteria and better comprehension of magnetotactic bacteria. In this study, an aerobic magnetotactic bacterium YSC-1 was isolated from sediments in the Yellow Sea Cold Water Mass (YSCWM). In TEM, magnetic cells have one or several circular magnetosomes in diameter of 100nm, and consist of Fe and Co shown on energy dis-persive X-ray spectrum. The biological and physiological characteristics of this bacterium were also de-scribed. The colour of YSC-1 colony is white in small rod. The gram stain is negative. Results showed that Strain YSC-1 differs from microaerophile magnetotactic bacteria MS-1 and WD-1 in biology. 展开更多
关键词 magnetotactic bacterium ISOLATION magnetosomeS
原文传递
The Influence of Magnetite Nanoparticles on Human Leukocyte Activity
16
作者 Anezka Dzarova Martina Dubnickova +4 位作者 Vlasta Zavisovva Martina Koneracka Peter Kopcansky Hubert Gojzewski Milan Timko 《Journal of Life Sciences》 2010年第5期37-43,共7页
In this contribution the influence of chemically synthesized magnetite particles coated by sodium oleate and PEG (MPEG), and magnetosomes (MS) was gradually tested on the process of phagocytosis and the metabolic ... In this contribution the influence of chemically synthesized magnetite particles coated by sodium oleate and PEG (MPEG), and magnetosomes (MS) was gradually tested on the process of phagocytosis and the metabolic activity (lysozyme and peroxidase activity) in leukocyte. Lysozyme activity is oxygen-independent liquidation mechanisms of engulfed microorganism, peroxidase activity is oxygen-dependent one. The both tested samples MS and MPEG lysed leukocyte cells during incubation. MPEG with concentration 10 and 20 μg/mL lysed almost all leukocytes and their cell viability was in the 14 ± 0.05% range. On the other hand, MS begin to influence leukocytes activity at the concentration of 1 μg/mL and this influence grows with increasing concentration up to 20 μg/mL. MS are more suitable for biological applications than MPEG which are more aggressive material than MS and their using is unavailable for these types of the test mainly for the concentration 10 - 20 μg/mL. 展开更多
关键词 Human leukocytes activity magnetosomeS magnetite particles sodium oleate PEG
下载PDF
Properties of Magnetite Nanoparticles Produced by Magnetotactic Bacteria
17
作者 李文兵 YU Longjiang +4 位作者 ZHOU Pengpeng WANG Guanghua XU Binfu CHENG Zhengzai 徐卫国 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第6期1317-1322,共6页
The magnetic nanoparticles(magnetite) were prepared through the fermentation of the Magnetospirillum strain WM-1 newly isolated by our group. The samples were characterized by TEM, SAED, XRD, rock magnetic analysis,... The magnetic nanoparticles(magnetite) were prepared through the fermentation of the Magnetospirillum strain WM-1 newly isolated by our group. The samples were characterized by TEM, SAED, XRD, rock magnetic analysis, and Mossbauer spectroscopy. TEM and SAED measurements showed that the magnetosomes formed by strain WM-1 were single crystallites of high perfection with a cubic spinel structure of magnetite. X-ray measurements also fitted very well with standard Fe3O4 reflections with an inverse spinel structure of the magnetite core. The size of crystal as calculated by the Debye-Scherrer’s equation was approximately 55 nm. Rock magnetic analysis showed WM-1 synthesized single-domain magnetite magnetosomes, which were arranged in the form of linear chain. The high delta ratio((δFC / δZFC = 4) supported the criteria of Moskowitz test that there were intact magnetosomes chains in cells. The Verwey transition occurred at 105 K that closed to stoochiometric magnetite in composition. These observations provided useful insights into the biomineralization of magnetosomes and properties of M. WM-1 and potential application of biogenic magnetite in biomaterials and biomagnetism. 展开更多
关键词 biogenic magnetite magnetotactic bacteria property magnetosome biomineralization
原文传递
Biomineralized and chemically synthesized magnetic nanoparticles:A contrast
18
作者 Tanya NANDA Ankita RATHORE Deepika SHARMA 《Frontiers of Materials Science》 SCIE CSCD 2020年第4期387-401,共15页
Magnetic nanoparticles(MNPS)have widely been synthesized through chemical processes for biomedical applications over the past few decades.Recently,a new class of MNPs,known as bacterial magnetosomes,has been isolated ... Magnetic nanoparticles(MNPS)have widely been synthesized through chemical processes for biomedical applications over the past few decades.Recently,a new class of MNPs,known as bacterial magnetosomes,has been isolated from magnetotactic bacteria,a natural source.These magnetosomes are magnetite or greigite nanocrystals which are biomineralized in the bacterial cell and provide magnet-like properties to it.Contrary to MNPs,bacterial magnetosomes are biocompatible,lower in toxicity,and can be easily cleared from the body due to the presence of a phospholipid bilayer around them.They also do not demonstrate aggregation,which makes them highly advantageous.In this review,we have provided an in-depth comparative account of bacterial magnetosomes and chemically synthesized MNPs in terms of their synthesis,properties,and biomedical applications.In addition,we have also provided a contrast on how magnetosomes might have the potential to successfully substitute synthetic MNPs in therapeutic and imaging applications. 展开更多
关键词 bacterial magnetosomes magnetic nanoparticles iron nanoparticles magnetotactic bacteria magnetosomeS
原文传递
Characteristics of magnetotactic bacteria in Duanjiapo loess section, Shaanxi Province and their environment significance 被引量:5
19
作者 贾蓉芬 颜备战 +2 位作者 李荣森 范国昌 林本海 《Science China Earth Sciences》 SCIE EI CAS 1996年第5期478-485,共8页
Magnetotactic bacteria (MB) have been isolated from 61 samples which have been collected from S0, L1, S1 and L2 layers in the Duanjiapo loess section. A few MB (<25 cell counts per sieve mesh) have been found in lo... Magnetotactic bacteria (MB) have been isolated from 61 samples which have been collected from S0, L1, S1 and L2 layers in the Duanjiapo loess section. A few MB (<25 cell counts per sieve mesh) have been found in loess layers (L1, L2), bow-shaped, each cell containing only two magnetosomes. while much more MB (>125 cells counts per sieve mesh) have been found from paleosol layers (S0, S1), rod-shaped, each cell containing 8-26 magnetosomes arranged in irregular chains. Magnetosomes with Fe and Co as the main metallic elements are spheroid-shaped, and mainly round in cross-section. Normal saturated fatty acids in MB ranged from C14 to C28; almost no monounsaturated fatty acids have been identified. Most suitable oxygen content for MB growing is 10%, and low concentration of organic salt (0.02mmol/L qumsic iron) is beneficial to the forming of magnetosomes. Results suggest that the paleosol development stage is suitable for the growing of MB and the climate fluctuation periods for magnetosomes formation. 展开更多
关键词 LOESS SECTION magnetotactic bacteria (MB) magnetosome ENVIRONMENT significance.
原文传递
Production,Modifi cation and Bio-Applications of Magnetic Nanoparticles Gestated by Magnetotactic Bacteria 被引量:6
20
作者 Jin Xie Kai Chen Xiaoyuan Chen 《Nano Research》 SCIE EI CSCD 2009年第4期261-278,共18页
Magnetotactic bacteria(MTB)were first discovered by Richard P.Blakemore in 1975,and this led to the discovery of a wide collection of microorganisms with similar features i.e.,the ability to internalize Fe and convert... Magnetotactic bacteria(MTB)were first discovered by Richard P.Blakemore in 1975,and this led to the discovery of a wide collection of microorganisms with similar features i.e.,the ability to internalize Fe and convert it into magnetic nanoparticles,in the form of either magnetite(Fe_(3)O_(4))or greigite(Fe_(3)S_(4)).Studies showed that these particles are highly crystalline,monodisperse,bioengineerable and have high magnetism that is comparable to those made by advanced synthetic methods,making them candidate materials for a broad range of bio-applications.In this review article,the history of the discovery of MTB and subsequent efforts to elucidate the mechanisms behind the magnetosome formation are briefly covered.The focus is on how to utilize the knowledge gained from fundamental studies to fabricate functional MTB nanoparticles(MTB-NPs)that are capable of tackling real biomedical problems. 展开更多
关键词 Magnetotactic bacteria(MTB) magnetosome bio-application magnetic resonance imaging(MRI)
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部