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論文

論文
Maki, Teruya ; Kakikawa, Makiko ; Kobayashi, Fumihisa ; Yamada, Maromu ; Matsuki, Atsushi ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Atmospheric Environment.  74  pp.73-82,  2013-08-01.  Elsevier
URL: http://hdl.handle.net/2297/34677
概要: Long-range transport of airborne microorganisms through the free troposphere significantly impacts biological ecosystems , human life, and atmospheric processes in downwind areas. However, microbial communities in the free troposphere have rarely been investigated because the direct collection of microbial cells at high altitudes requires sophisticated sampling techniques. In this study, tropospheric air sampling was performed using a balloon and an aircraft at 800 m and 3000 m, respectively, over the Noto Peninsula in Japan (37.5°N, 137.4°E) where free tropospheric winds carry aerosols from continental areas. The air samples were collected during four different sampling periods when air masses came from desert regions of Asian continent (west samples) and from Siberia of Russia North Asia (north samples). The west samples contained higher levels of aerosols, and bacteria from the west samples grew in culture media containing up to 15% NaCl. In contrast, bacteria from the north samples could not be cultured in the same media. All isolates obtained from the NaCl-amended cultures were similar to Bacillus subtilis and classified as Firmicutes. A 16S rDNA clone library prepared from the west samples was mainly composed of one phylotype of Firmicutes that corresponded to the cultured B. subtilis sequence. A clone library prepared from the north samples consisted primarily of two phyla, i.e., Actinobacteria and Proteobacteria, which are known to dominantly inhabit low-temperature environments of North Asia. Our results suggest that airborne bacterial communities at high altitudes include several species that vary by the direction and interaction of free tropospheric winds. •Aerosol samples were collected at high altitudes using an aircraft and a balloon.•During four sampling periods, the air masses came from the Gobi Desert and North Asia.•Airborne bacterial species were investigated using a 16S rDNA clone library technique.•Bacterial species at high altitudes varied by the direction of free tropospheric winds. © 2013 Elsevier Ltd. 続きを見る
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論文

論文
Maki, Teruya ; Kobayashi, Fumihisa ; Yamada, Maromu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Aerobiologia.  29  pp.341-354,  2013-09-01.  Springer
URL: http://hdl.handle.net/2297/34678
概要: Bioaerosol particles including bacteria, fungi, and virus are originated from marine and terrestrial environments. The a irborne microorganisms are transported for long distance through the free troposphere and are thought to influence the downwind ecosystems and human life. However, microbial communities in the free troposphere have not been understood in detail because the direct sampling of microbial cells at high altitude requires sophisticated sampling techniques. In this study, for the investigation of microbial species compositions in the free troposphere, air sampling using an aircraft was performed over the Noto Peninsula in Japan, where the tropospheric winds carry aerosol particles from continental areas. Two air samples were collected at 3,000 m on March 27, 2010, when air mass was carried from the Gobi Desert to Japan area. Microorganisms from one air sample grew in culture media containing up to 15 % NaCl, suggesting that halotolerant bacteria maintain their viabilities in the free troposphere. DGGE analysis revealed that the amended cultures were dominated by Bacillus subtilis, and the isolates obtained from the amended cultures were identical to B. subtilis. Furthermore, the 16S rDNA clone library (culture-independent survey) of the other air sample grew was composed of three phylotypes belonging to Firmicutes, Bacteroidetes, and Proteobacteria with the sequences of Firmicutes phylotype corresponding to that of the cultured B. subtilis sequence. Microscopic observation using FISH method indicated that B. subtilis particles occupied 80 % of total eubacterial particles on the mineral particles. The halotolerant bacteria identical to B. subtilis would dominate at high altitudes over Noto Peninsula where the prevailing westerly wind was blowing. © 2012 Springer Science+Business Media Dordrecht. 続きを見る
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論文
Maki, Teruya ; Susuki, Shinzi ; Kobayashi, Fumihisa ; Kakikawa, Makiko ; Tobo, Yutaka ; Yamada, Maromu ; Higashi, Tomomi ; Matsuki, Atsushi ; Hong, Chunsang ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Science of the Total Environment.  408  pp.4556-4562,  2010-09-01.  Elsevier BV
URL: http://hdl.handle.net/2297/25291
概要: 金沢大学理工研究域物質化学系<br />The microbial communities transported by Asian desert dust (KOSA) events have attracted much attenti on as bioaerosols because the transported microorganisms are thought to influence the downwind ecosystems in Korea and Japan. However, the atmospheric microbial community has not been investigated at high altitude in the KOSA arrival area. In this study, to estimate the viability and diversity of atmospheric halotolerant bacteria, which are expected to resist to various environmental stresses as well as high salinities, bioaerosol samples were collected at 10 and 600. m above the ground within the KOSA arrival area, Suzu City, Japan, during KOSA events. During the sampling period, the particle numbers at 600. m were higher than those at 10. m, suggesting that large particles of aerosol fall from the high altitude of 600. m to the ground surface. The microorganisms in bioaerosol samples grew in media containing up to 15% NaCl concentrations demonstrating the viability of the halotolerant bacteria in bioaerosol samples. The PCR-DGGE analysis using 16S rDNA revealed that the bacterial species in NaCl-amended cultures were similar to the bacteria detected from the genomic DNA directly extracted from the bioaerosol samples. The 16S rDNA sequences of bacterial communities in bioaerosol samples were classified into 4 phylotypes belonging to the Bacillus cereus or Bacillus subtilis group. The bioaerosol samples collected at 600. m included 2 phylotypes belonging to B. subtilis, and one phylotype among all 4 phylotypes was identical between the samples at 10 and 600. m. In the atmosphere at 600. m, the halotolerant bacterial community was expected to remain viable, and the species composition was expected to include a few species of the genus Bacillus. During this investigation period, these atmospheric bacteria may have been vertically transported to the ground surface, where the long-range KOSA particle transport from China is frequently observed. © 2010 Elsevier B.V. 続きを見る
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論文
Maki, Teruya ; Puspitasari, Findya ; Hara, Kazutaka ; Yamada, Maromu ; Kobayashi, Fumihisa ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Science of the Total Environment.  488-489  pp.75-84,  2014-08-01.  Elsevier
URL: http://hdl.handle.net/2297/37588
概要: Asian dust (Kosa) events transport airborne microorganisms that significantly impact biological ecosystems, human health , and ice-cloud formation in downwind areas. However, the composition and population dynamics of airborne bacteria have rarely been investigated in downwind areas during Kosa events. In this study, air samplings were sequentially performed at the top of a 10-m high building within the Kosa event arrival area (Kanazawa City, Japan) from May 1 to May 7, 2011, during a Kosa event. The particle concentrations of bacterial cells and mineral particles were ten-fold higher during the Kosa event than on non-Kosa event days. A 16S ribosomal DNA clone library prepared from the air samples primarily contained sequences from three phyla: Cyanobacteria, Firmicutes, and Alphaproteobacteria. The clones from Cyanobacteria were mainly from a marine type of Synechococcus species that was dominant during the first phase of the Kosa event and was continuously detected throughout the Kosa event. The clones from Alphaproteobacteria were mainly detected at the initial and final periods of the Kosa event, and phylogenetic analysis showed that their sequences clustered with those from a marine bacterial clade (the SAR clade) and Sphingomonas spp. During the middle of the Kosa event, the Firmicutes species Bacillus subtilis and Bacillus pumilus were predominant; these species are known to be predominant in the atmosphere above the Chinese desert, which is the source of the dust during Kosa events. The clones obtained after the Kosa event had finished were mainly from Bacillus megaterium, which is thought to originate from local terrestrial areas. Our results suggest that airborne bacterial communities at the ground level in areas affected by Kosa events change their species compositions during a Kosa event toward those containing terrestrial and pelagic bacteria transported from the Sea of Japan and the continental area of China by the Kosa event. © 2014 Elsevier B.V. 続きを見る
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論文
Maki, Teruya ; Hara, Kazutaka ; Kobayashi, Fumihisa ; Kurosaki, Yasunori ; Kakikawa, Makiko ; Matsuki, Atsushi ; Chen, Bin ; Shi, Guangyu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Atmospheric Environment.  119  pp.282-293,  2015-10-01.  Elsevier
URL: http://hdl.handle.net/2297/44871
概要: Bacterial populations transported from ground environments to the atmosphere get dispersed throughout downwind areas and can influence ecosystem dynamics, human health, and climate change. However, the vertical bacterial distribution in the free troposphere was rarely investigated in detail. We collected aerosols at altitudes of 3000 m, 1000 m, and 10 m over the Noto Peninsula, Japan, where the westerly winds carry aerosols from continental and marine areas. During the sampling period on March 10, 2012, the air mass at 3000 m was transported from the Chinese desert region by the westerly winds, and a boundary layer was formed below 2000 m. Pyrosequencing targeting 16S rRNA genes (16S rDNA) revealed that the bacterial community at 3000 m was predominantly composed of terrestrial bacteria, such as Bacillus and Actinobacterium species. In contrast, those at 1000 m and 10 m included marine bacteria belonging to the classes Cyanobacteria and Alphaproteobacteria. The entire 16S rDNA sequences in the clone libraries were identical to those of the terrestrial and marine bacterial species, which originated from the Chinese desert region and the Sea of Japan, respectively. The origins of air masses and meteorological conditions contribute to vertical variations in the bacterial communities in downwind atmosphere. © 2015 Elsevier Ltd. All rights reserved.<br />Embargo Period 24 months 続きを見る
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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
出版情報: Deep-Sea Research Part I: Oceanographic Research Papers.  118  pp.37-45,  2016-12-01.  Elsevier
URL: http://hdl.handle.net/2297/46781
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
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論文

論文
Puspitasari, Findya ; Maki, Teruya ; Shi, Guangyu ; Bin, Chen ; Kobayashi, Fumihisa ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Air Quality, Atmosphere and Health.  9  pp.631-644,  2016-09-01.  Springer Verlag
URL: http://hdl.handle.net/2297/43402
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
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論文
Maki, Teruya ; Hara, Kazutaka ; Kobayashi, Fumihisa ; Kurosaki, Yasunori ; Kakikawa, Makiko ; Matsuki, Atsushi ; Bin, Chen ; Shi, Guangyu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Atmospheric Environment.  119  pp.282-293,  2015-10-01.  Elsevier Ltd.
URL: http://hdl.handle.net/2297/46163
概要: Bacterial populations transported from ground environments to the atmosphere get dispersed throughout downwind areas and can influence ecosystem dynamics, human health, and climate change. However, the vertical bacterial distribution in the free troposphere was rarely investigated in detail. We collected aerosols at altitudes of 3000 m, 1000 m, and 10 m over the Noto Peninsula, Japan, where the westerly winds carry aerosols from continental and marine areas. During the sampling period on March 10, 2012, the air mass at 3000 m was transported from the Chinese desert region by the westerly winds, and a boundary layer was formed below 2000 m. Pyrosequencing targeting 16S rRNA genes (16S rDNA) revealed that the bacterial community at 3000 m was predominantly composed of terrestrial bacteria, such as Bacillus and Actinobacterium species. In contrast, those at 1000 m and 10 m included marine bacteria belonging to the classes Cyanobacteria and Alphaproteobacteria. The entire 16S rDNA sequences in the clone libraries were identical to those of the terrestrial and marine bacterial species, which originated from the Chinese desert region and the Sea of Japan, respectively. The origins of air masses and meteorological conditions contribute to vertical variations in the bacterial communities in downwind atmosphere. © 2015 Elsevier Ltd. All rights reserved.<br />Embargo Period 24 months 続きを見る
9.

論文

論文
Maki, Teruya ; Kobayashi, Fumihisa ; Yamada, Maromu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
出版情報: Aerobiologia.  29  pp.341-354,  2013-09-01.  Japan Surgical Society / Springer Science+Business Media Dordrecht
URL: http://hdl.handle.net/2297/35648
概要: Bioaerosol particles including bacteria, fungi, and virus are originated from marine and terrestrial environments. The a irborne microorganisms are transported for long distance through the free troposphere and are thought to influence the downwind ecosystems and human life. However, microbial communities in the free troposphere have not been understood in detail because the direct sampling of microbial cells at high altitude requires sophisticated sampling techniques. In this study, for the investigation of microbial species compositions in the free troposphere, air sampling using an aircraft was performed over the Noto Peninsula in Japan, where the tropospheric winds carry aerosol particles from continental areas. Two air samples were collected at 3,000 m on March 27, 2010, when air mass was carried from the Gobi Desert to Japan area. Microorganisms from one air sample grew in culture media containing up to 15 % NaCl, suggesting that halotolerant bacteria maintain their viabilities in the free troposphere. DGGE analysis revealed that the amended cultures were dominated by Bacillus subtilis, and the isolates obtained from the amended cultures were identical to B. subtilis. Furthermore, the 16S rDNA clone library (culture-independent survey) of the other air sample grew was composed of three phylotypes belonging to Firmicutes, Bacteroidetes, and Proteobacteria with the sequences of Firmicutes phylotype corresponding to that of the cultured B. subtilis sequence. Microscopic observation using FISH method indicated that B. subtilis particles occupied 80 % of total eubacterial particles on the mineral particles. The halotolerant bacteria identical to B. subtilis would dominate at high altitudes over Noto Peninsula where the prevailing westerly wind was blowing. © 2012 Springer Science+Business Media Dordrecht. 続きを見る