※一部利用できない機能があります
| 1.
論文 |
論文
|
Maki, Teruya ; Aoki, Kazuma ; Kobayashi, Fumihisa ; Kakikawa, Makiko ; Tobo, Yutaka ; Matsuki, Atsushi ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
金沢大学理工研究域物質化学系<br />Microbial particles transported by Asian desert dust (KOSA) possibly impact ecosystems and human hea
…
lth in downwind environments and are commonly called "bioaerosols." The microbial communities associated with KOSA mineral particles (KOSA bioaerosol), which were collected from the snow cover on Mt. Tateyama, were investigated by means of a culture-amendment technique combined with denaturing gradient gel electrophoresis (DGGE) analysis using 16S rRNA genes. After the stratigraphy of the snow layer formed on the walls of a snow pit on Mt. Tateyama, samples were collected from 2 layers, which included KOSA particles and one which did not. The snow samples with KOSA particles indicated microbial growth in the 100 and 10-1 dilution media and in the medium with NaCl below 10%, while the snow sample without KOSA particles showed no microbial growth in the culture media. The PCR-DGGE analysis revealed that the bacterial compositions in the snow samples including KOSA mineral particles were mainly composed of the members of the phyla Actinobacteria, Firmicutus, and Proteobacteria. In particular, the 2 phylotypes appeared in the microbial cultures were similar to the members of the B. subtilis group, which has been detected in bioaerosol samples collected from the atmosphere over KOSA arrival (Suzu City) and source (Dunhuang City) regions. Presumably, halotolerant and oligotrophic bacterial communities are associated with the KOSA particles that descend to the snow cover on Mt. Tateyama. © 2011 Springer Science+Business Media B.V.
続きを見る
|
||||
| 2.
論文 |
論文
|
Maki, Teruya ; Takeda, Noriko ; Hasegawa, Hiroshi ; Ueda, Kazumasa
概要:
金沢大学大学院自然科学研究科物質情報解析<br />Chemical warfare agents, composed of harmful organoarsenic compounds have contaminated the soi
…
ls of Ohkunoshima Island with high levels of arsenic. As a basic research establishing useful bioremediation techniques, environmental factors such as arsenic concentrations and bacterial biomass in the soils were investigated. Among the five stations of Ohkunoshima Island, the soils of four stations were contaminated by high levels of arsenic compounds at concentrations of 125,12.7, 3.29 and 0.504 g/kg soil, while the other station with low arsenic concentrations of 0.007 g/kg soil was considered an uncontaminated area. The distribution of arsenic compounds originating from the chemical weapon agent differs among the various areas of Ohkunoshima Island. The cell densities of arsenate-resistant bacteria also varied among the five stations, ranging from 106 to 108 cells/g soil. In an attempt to isolate bacteria that strongly mineralize the organoarsenic compounds, the mineralization activities for monomethylarsonic acid [MMAA(V)] of 48 isolates of arsenate-resistant bacteria were determined. Only nine isolates reduced 140 μg/1 of MMAA(V), giving decreasing percentages ranging from 5 to 100% within 14 days. Among the nine isolates, two remarkably converted 140 μg/1 of MMAA to more than 71 μg/1 of inorganic arsenic. Presumably only specific members of the environmental bacterial population have strong mineralization activities for MMAA. Phylogenetic analysis using 16S rDNA sequences showed that the two isolates belonged to the Pseudomonas putida strains, which are known to have strong mineralization activity for various organic compounds. In the soil contaminated by arsenic at a high level, few bacteria in the arsenate-resistant bacterial group would significantly mineralize organoarsenic compounds. Copyright © 2006 John Wiley & Sons, Ltd.
続きを見る
|
||||
| 3.
論文 |
論文
|
Kong, Qingquan ; Nakai, Yuji ; Kuroda, Nanae ; Shiratsuchi, Akiko ; Nagaosa, Kaz ; Nakanishi, Yoshinobu
概要:
Interaction between the host and pathogen determines the fate of both organisms during the infectious state. The host is
…
equipped with a battery of immune reactions, while the pathogen displays a variety of mechanisms to compromise host immunity. Although bacteria alter their pattern of gene expression in host organisms, studies to elucidate the mechanism behind this are only in their infancy. We here examined the possibility that host immune proteins directly participate in the change of gene expression in bacteria. Escherichia coli was treated with a mixture of the extracellular region of peptidoglycan recognition protein (PGRP)-LC and the antimicrobial peptide attacin of Drosophila, and subjected to DNA microarray analysis for mRNA repertoire. We identified 133 annotated genes whose mRNA increased after the treatment, and at least four of them were induced in response to PGRP-LC. One such gene, lipoprotein-encoding nlpI, showed a transient increase of mRNA in adult flies depending on PGRP-LC but not PGRP-LE. NlpI-lacking E. coli had a lowered growth rate and/or viability in flies than the parental strain. These results suggest that a host immune receptor triggers a change of gene expression in bacteria simultaneously with their recognition and induction of immune responses. © The Authors 2015. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.
続きを見る
|
||||
| 4.
論文 |
論文
|
Tazaki, Kazue ; Asada, Ryuji
概要:
金沢大学大学院自然科学研究科環境動態<br />Mercury is a toxic substance that is widely distributed throughout the hydrosphere, biosphere, a
…
nd lithosphere. Mine waste environments and mine waters support a wide diversity of microbial life. The microbial ecology of environments where mine waters are polluted with heavy metals is poorly understood. Here, we describe the features of bacteria in mercury-contaminated gold panning ponds in a small-scale gold mine (Geita) near Lake Victoria, Tanzania using energy filtering transmission electron microscopy (EF-TEM) and scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy (STEM-EDX). Most bacteria in the panning pond showed thick exopolysaccharides (EPSs), and many clay minerals attached onto the surface of EPSs. The clay minerals and EPSs might act as protective layers for the bacteria against toxic materials. The clay minerals were composed of smectite, halloysite, and kaolinite associated with calcite and goethite. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy indicated that the bulk soil samples contained abundant Si, Al, K, Ca, and Fe with heavy metals such as Au, Ti, and Ag. The results indicate that Hg pollution from panning ponds is caused by not only volatilization of Hg from Au-Hg amalgams, but Hg is also released into the air as dust mixed with dry fine clays, suggesting high long-term environmental risks. Mercury-resistant bacteria associated with clay minerals may have a significant effect on the weathering processes of the ore during long-term bioremediation. The clay mineral complexes on the surface of bacterial cell walls are a stimulator for Hg-resistant bacterial growth in mud ponds contaminated with the Au-Hg materials. 全文公開200809
続きを見る
|
||||
| 5.
論文 |
論文
|
伊牟田, 盱 ; 田崎, 和江 ; Imuta, Miharu ; Tazaki, Kazue
概要:
Red brownish microbial mats grow on the surface of drainage pond at Iriki Kaolin deposit, Kagoshima Prefecture, Japan, a
…
re predominantly iron oxidizing bacteria. The Fe-bacteria quickly occur on the surface of acidic water pH 3.4 within few days. The biofilms are composed of amorphous iron hydroxides and ferrihydrite are found both in natural system and cultured solution after 90 days under pH 6→2.5 condition. Optical and SEM-EDX microscopy showed the formation processes of Fe-rich biofilms with green unicellular bacteria occurred in the system of deionized water and kaolinite blocks. In the system, Fe and S-rich biofilms around kaolinite blocks can be seen, suggesting kaolin minerals encourage to form the biofilms as accelerator in the acidic drainage pond. The biofilms use ferrous ions as their energy source through the oxidation into ferric ions.
続きを見る
|
||||
| 6.
論文 |
論文
|
田崎, 和江 ; Tazaki, Kazue
概要:
The weathering process has generally been considered from only a chemical/physical point of view, however recent observa
…
tions of bacteria in weathered rocks have, led to questions about the importance of microbial activity. In order to examine this, an outdoor natural experiment has been performed in which an andesite rocky hill was immersed in running ground water at outside temperature for one year. The ground water is harvested from a depth of 150m for the establishment of the systems. The system was constructed in Kakuma Campus, Kanazawa University on April 2007, having the foot baths heated at 37℃ with disinfectant and the rocky hill with running natural ground water without any chemical and heating treatments. After 3 months of incubation in the footbath, biomineralization of carbonate minerals (calcite and aragonite) by Cyanobacteria was found. On the other hand, after one year, clay minerals (Smectite) and zeolite (Heulandite and Clinoptilolite) were found in only the rocky hill under natural conditions. Various kinds of microorganisms, such as Cyanobacteria, diatoms and bacteria accelerated weathering reactions of andesite (Tomuro-ishi) for building materials eroded on the surface, and to produce secondary minerals of bio-clays and zeolites. The microorganisms carry an important role to change water quality within such a short period. Large crystals of zeolite and fine thin films of smectite attached to the microorganisms with cohesion organics to form green microbial mats on the surface of the andesite rocky hill, showing accumulation of elements such as Al and Si which could have been derived by dissolution of the rocks associated with running water. These data collectively demonstrate the microbial formation of smectite and zeolite of bio-clays, where the reaction rates may be substantially enhanced by the presence of microorganisms. Bacteria and diatom activity may hence have a great influence on the clay mineral developments commonly observed in naturally weathered rocks. The mechanism of bio-clays formation has important implications for water-rock interactions both in natural environments and in polluted areas. The footbath facilities will be made available for use not only in research, but also for the advancement of education while contributing to the local community.
続きを見る
|
||||
| 7.
論文 |
論文
|
Maki, Teruya ; Ishikawa, Akira ; Mastunaga, Tomoki ; Pointing, Stephen B. ; Saito, Yuuki ; Kasai, Tomoaki ; Watanabe, Koichi ; Aoki, Kazuma ; Horiuchi, Amane ; Lee, Kevin C. ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Atmospheric aerosols contain particulates that are deposited to oceanic surface waters. These can represent a major sour
…
ce of nutrients, trace metals, and organic compounds for the marine environment. The Japan Sea and the western Pacific Ocean are particularly affected by aerosols due to the transport of desert dust and industrially derived particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5) from continental Asia. We hypothesized that supplementing seawater with aerosol particulates would lead to measurable changes in surface water nutrient composition as well as shifts in the marine microbial community. Shipboard experiments in the Pacific Ocean involved the recovery of oligotrophic oceanic surface water and subsequent supplementation with aerosol particulates obtained from the nearby coastal mountains, to simulate marine particulate input in this region. Initial increases in nitrates due to the addition of aerosol particulates were followed by a decrease correlated with the increase in phytoplankton biomass, which was composed largely of Bacillariophyta (diatoms), including Pseudo-nitzschia and Chaetoceros species. This shift was accompanied by changes in the bacterial community, with apparent increases in the relative abundance of heterotrophic Rhodobacteraceae and Colwelliaceae in aerosol particulate treated seawater. Our findings provide empirical evidence revealing the impact of aerosol particulates on oceanic surface water microbiology by alleviating nitrogen limitation in the organisms. © 2016 Elsevier Ltd<br />Embargo Perion 12 months
続きを見る
|
||||
| 8.
論文 |
論文
|
Puspitasari, Findya ; Maki, Teruya ; Shi, Guangyu ; Bin, Chen ; Kobayashi, Fumihisa ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Airborne microorganisms (bioaerosol) from the China desert region, which are released into the atmosphere, disperse by t
…
he Asian dust event and affect ecosystems, human life, and atmospheric processes in downwind areas. However, the dynamics of airborne bacteria over the China desert regions have rarely been investigated. In this study, we analyzed bacterial communities in aerosols of the Asian dust source region (Taklimakan Desert) and compared them with the bacterial communities in sand dunes, for evaluating the mixtures from sand area to atmosphere. Air samples were collected at 10 m above the ground level from Dunhuang City during a dust event. The cell densities of airborne bacteria during a dust event were ten times more than that in non-dust periods. The 16S rDNA clone libraries from four air samples mainly belonged to two phyla, Firmicutes and Proteobacteria. During a dust event, the proportion of Proteobacteria clones decreased, whereas that of Firmicutes clones increased. Sand samples were collected from the sand dunes in four sampling sites of the Taklimakan Desert. The bacterial communities in sand samples comprised of the members of Firmicutes and Actinobacteria. The clones of Firmicutes in both air and sand samples included Bacillus species, constituting more than 10 % of total clones. Airborne bacterial communities would be carried by the dust events from sand dunes. Propionibacterium species from the class Actinobacteria that were dominant in sand samples were not detected in the air samples, suggesting that atmospheric stressors eliminate some bacterial species. Presumably, airborne bacterial communities in the Asian dust source region are composed of local environmental bacteria, and their dynamics depend on the occurrence of a dust event. © 2015 Springer Science+Business Media Dordrecht<br />Embargo Period 12 months
続きを見る
|
||||
| 9.
論文 |
論文
|
田崎, 和江 ; 朝田, 隆二 ; 池田, 頼正
概要:
Biofilms quickly occur on the water surface, associated with Fe-bacteria, such as Leptothrix sp., Gallionella sp. and To
…
xothrix sp. are the most common pioneering species in microbial communities. The bacterial colonies form, Fe-rich biofilms within a few days which is active oxic zone of the top water surface. Biofilms are composed of amorphous iron hydroxides, goethite, ferrihydrite and schwertmannite Fe8O8(OH) 6S04 (2.5 and 1.5 Å) are found both in natural system and cultured solution. SEM-EDX, TEM and atomic-force microscopy showed the formation processes of Fe-rich biofilms with sub-micron rugged structure on the primitive stage. In this paper biomineral structure of Fe-rich biofilms collected from underground water at three places was described. The structure is affected by the water physical and chemical environment (anaerobic or oxidized condition), bacterial species, water chemical composition, and species interactions. The old idea of the biofilms is simply microbes suspended in a homogeneous, but in this study variety of microorganisms with Fe-rich cell was revealed. Brownish black biofilms grow on the surface of underground water in the Kakuma Campus of Kanazawa University, are of predominantly iron oxidizing bacteria, such as Leptothrix sp., Gallionella sp. and Toxothrix sp. The biofilms use ferrous ions as their energy source through the oxidation into ferric ions. TEM of the biofilms have revealed mucoid substances of bacteria, like polysaccharides are effective for adhesion of iron hydroxides produced through biomineralization of various bacterial communities. The quick condensation process of ordered iron bacterial colonies considered to be a factor for increasing the thickness of biofilms. This is the first time oriented Fe-bacterial sheet/nets in the colonies have been found in biofilms within a few days aging time. The formation mechanism of biofilms on the water surface can be apply science to implants to be placed in the human body in biomedical applications, such as catheter, heartlung machine, and contact lenses.
続きを見る
|
||||
| 10.
論文 |
論文
|
Tazaki, Kazue ; Hattori, Tatsuya
|
