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Tazaki, Kazue ; Ishida, Hideki ; 田崎, 和江 ; 石田, 秀樹
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金沢大学理工研究域地球社会基盤学系
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白石, 秀一 ; 高橋, 直人 ; 霜島, 康浩 ; 朝田, 隆二 ; 渡辺, 弘明 ; 田崎, 和江 ; Shiraishi, Shuichi ; Takahashi, Naoto ; Shimojima, Yasuhiro ; Asada, Ryuji ; Watanabe, Hiroaki ; Tazaki, Kazue
概要:
金沢大学理工研究域地球社会基盤学系<br />Bluish green Zn-S-and yellowish brown Fe-microbial mats were found on outer surfaces of well rise
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r pipes on Kakuma campus of Kanazawa University, Ishikawa Prefecture. The microscopic observation and XRF chemical analysis revealed that the formative conditions of microbial mats differ in depth due to stationary and pumping groundwater levels. Bluish green microbial mats formed in 61.6-75.6 m depth were characterized by high content of Zn and S. The microbial mats mainly consist of spherical fifine particles of several Am in size. A small amount of coccoid-and bacilli-form bacteria were found in the aggregation. While, yellowish brown microbial mats formed in 30.8-61.6 m depth and were characterized by high content of Fe, Ca, P, Si and Zn. The microbial mats mainly consist of spiral materials that were metabolized from an iron oxidizing bacterium, Gallionella ferruginea. Harp-like materials metabolized from another iron oxidizing bacteria, Toxothirixspp. were also found below 56 m in depth. A large amount of coccoid-, bacilli-and filamentous-form bacteria were found in the assemblage of the metabolic materials and the number of filamentous-form bacteria increased with depth.TEM observations and FE-TEM-EDX elemental maps revealed that some spherical particles on the cell surface of bacteria in the bluish green microbial mats are rich in Zn and S stick, suggesting that Zn exist as sulfide. The other adhesion materials consisted of Fe, Si, 0, and Zn were also formed around cell wall. The bacteria inthe bluish green microbial mats might be tolerant to heavy metal Zn.
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田代, 陽子 ; 田崎, 和江 ; Tashiro, Yoko ; Tazaki, Kazue
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金沢大学理工研究域地球社会基盤学系<br />角間川や金沢大学調整池ではLeptothrix sp., Gallionella sp.やToxothrix sp.といった鉄酸化細菌や,桿菌,球菌によって形成されている黄褐色のバイオマットがみ
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られる.本研究では現地での付着実験を行い,バイオマット形成の初期段階に着目し,主に透過型電子顕微鏡(TEM)を用いて観察,分析を行った.その結果,Toxothrix sp.の粘着物質(polysaccharides)が,水酸化鉄の微粒子を積極的に細胞壁に付着させる役割を担っていることが明らかになった.polysaccharidesのようなToxothrix sp.の粘着物質は,Fe^<2+>をFe^<3+>に換えてエネルギーを得る鉄酸化細菌のバイオミネラリゼーションによって生成された水酸化鉄が拡散するのを防ぎ,200nmのコロイド状微粒子として取り囲んだ状態で凝集させる.凝集した水酸化鉄のコロイド粒子はpolysaccharidesの薄膜から押し出された後もそれ自体で集合体を形成する.polysaccharidesは,水酸化鉄を固定し,その大きさを支配しながら鉄物質を固体にして堆積する役割を担っていることが示唆される.このような水酸化鉄の凝集形態は,バイオマットの厚みを増す要因である.<br />Brownish yellow microbial mats growing along the Kakuma River and at the controlling pond in the Kakuma Campus of Kanazawa University are of predominantly iron oxidizing bacteria, such as Leptothrix sp., Gallionella sp. and Toxothrix sp. Those microbial mats use ferrous ions as their energy source through the oxidation into ferric ions. Transmission electron microscopy of the primitive microbial mat, have revealed mucoid substances of Toxothrix sp. like polysaccharides are effective for adhesion of iron hydroxides produced through biomineralization of Toxothrix sp. Iron hydroxides coated with mucoid substances are coagulated into colloidal particles 200nm in size. Such condensed colloidal iron hydroxides grow into the aggregates and subsequently may be expelled outward from the thin membrane of polysaccharides. It is suggested that polysaccharides of Toxothrix sp. prevent dispersion of iron hydroxides and promote coagulation of iron materials. Such a condensation process of iron hydroxides is considered to be a factor for increasing the thickness of microbial mats.
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岸上, 佳史 ; 桜山, 和美 ; 田崎, 和江 ; 上島, 雅人 ; 渡辺, 弘明 ; Kishigami, Yoshifumi ; Sakurayama, Kazumi ; Tazaki, Kazue ; Ueshima, Masato ; Watanabe, Hiroaki
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金沢大学理工研究域地球社会基盤学系<br />尾小屋鉱山は緑色凝灰岩中にできた裂罅充填型浅熱水性の銅鉱床である.1971年に閉山するまで,当鉱山では黄鉄鉱,黄銅鉱,方鉛鉱,閃亜鉛鉱を産出していた.重金属は捨てられた鉱石から溶出し,河川へと流
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出している.石川県の尾小屋鉱山地域では,Fe,Cu,Zn,Cdがズリ捨て場から梯川へ流入している.本鉱山では,様々な色のバイオマットが第六立坑周辺に形成している.緑色のバイオマットに覆われている大量の茶色のバイオマットが坑口から続く谷川の河床に重金属を堆積している.これらのバイオマットは光学顕微鏡および走査型電子顕微鏡(SEM)を用いて観察を行った.また,バイオマットの鉱物および元素組成はX線粉末回折分析装置(XRD),蛍光X線分析装置(XRF)およびエネルギー分散分析装置(EDX)で分析を行った.坑水に含まれている主な重金属は,Fe(26.85mg/l),Cu(3.97mg/l),Zn(23.94mg/l),Cd(0.09mg/l)である.Fe,Zn,Cuやその他の金属が溶存している坑水中から,ピンク色バイオマットは銅を選択的に濃集し,また深緑色のバイオマットはFeを濃集している.ピンク色バイオマット中には自然銅,赤銅鉱,石英が存在していた.また,茶色のバイオマットはFeを選択的に濃集し,針鉄鉱やマグヘマイトといった鉱物を形成していた.バクテリアや藻類などの微生物はFeやCuといった重金属を細胞に吸着および濃集し生体鉱物を作ることが明らかになったので報告する.<br />Ogoya Mine in Ishikawa Prefecture, Japan, is one of the fissure-filling vein type copper deposits in the Green Tuff region. The mine contains pyrite, chalcopyrite, galena and sphalerite. Heavy metal ions dissolveed from abandoned metal-mine are common in waste water pool and stream. In the metal mining area, Fe, Cu, Zn and Cd are releasing from dumping area to the Kakehashi River. The drainage water contains Fe (26.85mg/l), Cu (3.97mg/l), Zn (23.94mg/l) and Cd (0.09mg/l). In this mine, various colored microbial mats (biomats) are grown around the No.6 pit drainage system. Abundant brown biomats covered with green biomats have fixed heavy metals on the drainage channel down the pithead. These biomats are observed by both optical and scanning electron microscopes (SEM). Minerals in the biomat and their chemical compositions were analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and energy dispersive X-ray analyzer (EDX). The reddish biomats fix Cu selectively from drainage water, whereas the dark green biomats fix Fe. Microorganisms, such as bacteria and algae, capture most of heavy metals as Fe- and Cu-minerals in/on the cell. It is clarified that copper and cuprite are formed in reddish biomats, and that goethite and maghemite are formed in the brown biomats.
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佐藤, 和也 ; 田崎, 和江 ; 奥野, 正幸 ; 久保, 博 ; Satoh, Kazuya ; Tazaki, Kazue ; Okuno, Masayuki ; Kubota, Hiroshi
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金沢大学理工研究域地球社会基盤学系<br />長野県の松代温泉は,大量のほう素(B)を含む温泉としてよく知られている.その排水溝には茶褐色および黒色のバイオマットが形成されている.特に河川水と温泉排水が交わる部分には黒色のバイオマットが形成
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されている.いずれのバイオマット中にも多量のBが濃集しており,これによって,排水中のB濃度は,排出直後よりも4割程度減少する.これは,バイオマット中に生息するシアノバクテリアがカルサイトを作る時に,二酸化炭素のかわりに炭酸塩イオンを取り込むからである.その際に細胞周辺に局所的に高アルカリ環境を作り出し,温泉中のHBO2を電離させ,よりBを他の物質に結合しやすい状態にするためである.シアノバクテリアはカルサイトを作り出すことによって,Bを濃集させ,温泉水中のBを軽減する働きがある.<br />Matsushiro Hot springs in Nagano Prefecture, Japan is known as one of the hot springs in which the concentration of boron (B) is quite high. The hot spring water drainage ditch was covered with dark brown microbial mats. Before the drainage meets the river, the microbial mats deposit is more than 2m in depth. The microbial mats deposit has two layers. In the upper parts, dark brown microbial mats covered the surface. Underneath are black microbial mats which make up a portion of the two layer structure. At the junction of the drainage and river water, only black microbial mats occurred. The aim of this study was to reduce the boron concentration of the drainage water with microbial mats at Matsushiro Hot Springs. ASS analysis showed that microbial mats collected from five different points contain 854mg B/kg, 8628mg Fe/kg, 120mg As/kg, and 912mg Mg/kg on average. ED-XRF analysis showed that all microbial mats contained more than 50wt% of Ca. XRD analysis and FT-IR spectra of the microbial mats indicated the presence of calcite. Observations by optical and electron microscopy showed that cyanobacteria inhabited dark brown microbial mats, whereas cyanobacteria and diatoms inhabited in black mierobial mats. Cyanobacteria use an enzyme named carbonate anhydrase (CA). HCO3- dissolved in the hot spring water was broken down into CO2 and OH- by CA. That OH- made temporary alkaline conditions around the cyanobacteria. Such alkaline conditions facilitate the break down of HBO2 into H+ and BO2-. BO2- can form many chemical compounds. The concentration of boron described in this study might have profound implications for bioremediation of boron contaminated sites.
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佐藤, 一博 ; 田崎, 和江
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Iron bacteria precipitate copious amounts of iron hydroxides in microbial mats normally inhabiting in ironrich water. In
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this study, the following findings were made on accumulation of Fe and the formation of ironsheath regarding L. ochracea, an iron bacterium which is one of the most common inhabitants of iron microbial mats at neutral pH collected from underground water, by an electron microscopic observation: (1) In a field experiment, the rate of inorganic precipitation is 1.6, and the rate of precipitation involving iron bacteria is 8.4, so that iron oxidizing bacteria are precipitating iron hydroxides in an amount five times or more of the inorganic precipitates. (2) By metabolic pathway of live L. ochracea, the iron sheath can be formed in a short time period. (3) UV-C treatment destroys the iron bacterial cells, thereby inhibiting the formation of iron-microbial mats. (4) At an early formation stage of iron- sheath of L. ochracea, a fine fibrous network structure is formed around the cell wall. The tubular sheath is composed of thicken fibrous materials. (5) By the metabolism of the iron bacterium, the oxidized Fe3+ is accumulated in the fine fibrous polysaccharide, thereby forming a sheath made of a complex of iron and an organic substance. (6) The fine particles of iron hydroxide found on the surface of the sheath are particles of iron hydroxide oxidized inorganically. (7) The matured sheath fixes low-crystalline ferrihydrite minerals in microbial mats. 鉄成分に富む水中には, 鉄細菌が生息しており, 黄褐色のバイオマットを形成している.本研究では, 中性の地下水に生成した鉄のバイオマット中に一般的に生息する鉄細菌Leptothrix ochraceaについて, 電子顕微鏡観察から, 鉄の濃集と鞘の形成過程について, 以下の知見を得た. (1) 野外において, 鉄の無機的な沈殿率は1.6, 鉄細菌が関与する沈殿率は8.4であり, 鉄細菌は無機沈殿の5倍以上の鉄を沈殿させる. (2) 生きているL.ochraceaの代謝により短時間で鉄鞘が形成される. (3) UV-C処理を行うことで, 鉄細菌の細胞が死滅し, 鉄バイオマットの形成が抑制される. (4) L.ochyaceaの鞘形成の初期段階は, 菌体の周囲に網目状の繊維物質を形成する.繊維が太くなることでチューブ状の鞘が形成される. (5) 鉄細菌の代謝によって酸化されたFe3+が繊維状多糖類に蓄積し, 鉄と有機物の複合体からなる鞘を形成する. (6) 鞘表面に認められる水酸化鉄の微粒子は, 無機化学的に酸化された水酸化鉄の粒子である. (7) 成熟した鞘は低結晶性のFerrihydriteを形成する.
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Tazaki, Kazue ; Okrugin, Victor M ; Okuno, Masayuki ; Belkova, Natalia ; Islam, ABM Rafiqul ; Chaerun, S. Khodijah ; Wakimoto, Rie ; Sato, Kazuhiro ; Moriichi, Shingo
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Department of Earth Sciences, Faculty of Science, Kanazawa University<br />Institute of Volcanology Far Eastern Division
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of Russian Academy of Sciences<br />Graduate School of Natural Science and Technology, Kanazawa University<br />This study described the investigation of microbial mats that are rich in iron, arsenic, and manganese in four hydrothermal systems of Kamchatka, Russia namely Vilyuchinskie, Mutnovskie, Nachikinskie, and Malkinskie. The hydrothermal systems (hot springs) are contributing to the metallic and non-metallic mineral resources of Russia such as oil, gas, coal, copper, nickel, cobalt, tin, mercury, lead, zinc, diamond, platinum, gold, and silver. We observed the biogeochemical activities of microorganisms originating from microbial mats. The structure and elemental composition of microbial mats in these hydrothermal systems were studied with optical microscopy and scanning electron microscopy equipped with energy dispersive X-ray analyzer (EDX), whereas the water quality of these springs was measured by using pack tests. Additionally, portable Y-ray analyzer was employed to determine the kind and quantity of Y-ray in the atmospheric condition of sampling areas. Optical and scanning electron microscopic observations revealed that the microbial mats at these springs were mainly composed of a large number of microorganisms such as bacteria (coccus, bacillus, and filamentous), cyanobacteria, and algae in association with biominerals. Bacterial fluorometric enumeration of the thermal water informed that the total number of bacteria was relatively low, while the fraction of enzymatically active bacteria was high ranging from 27 % to 91 %. Besides that, ƒﾁ-ray observation showed that the predominantly ƒﾁ-ray range was between 320-380 keV dominating in green and black-colored microbial mats at Vilyuchinskie hot springs. Correspondingly, heavy metal and minerals deposits accumulated at all these springs indicating that microorganisms may contribute to binding and formation of the minerals. These activities and heavy mineral encrustation of cyanobacteria, bacteria, and algae may contribute to the growth of the heavy metal deposit (such as iron, manganese, and arsenic) at these springs. Obviously, Kamchatka hot springs provide a model for studying the potential role of prokaryotes and eukaryotes in the origin of heavy metal and minerals formation.
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Nagai, Kaori ; Islam, ABM Rafiqul ; Tazaki, Kazue
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Islam, ABM Rafiqul ; Tazaki, Kazue
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