| 其他摘要 | 微生物可以通过代谢产酸促进硅酸盐和碳酸盐矿物风化释放CO2，也可以在陆地和水环境中形成碳酸盐矿物而固定CO2，无论从无机碳还是从有机碳角度，研究微生物对碳循环的驱动作用均有助于正确认识微生物与碳循环的关系，从而为碳循环的生物地球化学过程与地球表层环境演化的关系提供新的素材，因而具有重要研究价值。本文主要研究微生物-硅酸盐-碳酸盐矿物三者之间的相互作用及其对碳循环的影响，通过设置纯水和灭菌对照，以及不同养分条件和添加不同矿物含量等，对比研究细菌-硅酸盐-碳酸盐矿物相互作用及对碳循环的影响。通过测定试样的pH值、电导率、碳酸酐酶（CA）活性、释放的元素、代谢产物、微观形态观察和矿物晶体结构等参数综合分析细菌与矿物之间的相互作用；通过检测乙酸、5-羟甲基糠醛、2-羟基丁酸酮、乙酸甲酯和丁酸甲酯含量，探讨细菌风化矿物的作用机理；结合试样中HCO3-浓度、CO2饱和指数（SICO2）和矿物饱和指数等分析细菌-硅酸盐-碳酸盐矿物相互作用对碳循环的影响，为碳素微生物固定提供新的研究思路和基础资料。主要研究成果如下：1. 胶质芽孢杆菌-蛇纹石-方解石相互作用研究：在不同养分条件下，有N培养基中细菌风化矿物的作用程度远大于无N培养基中细菌对矿物的作用。无N培养基试样的pH值平均为7.44，而有N培养基试样的pH值平均为6.19，分析结果表明细菌可以通过分泌酸性有机物对矿物进行风化作用，如在有N培养基中分泌含量较高的乙酸对矿物产生酸溶作用。研究发现，适量方解石的添加有利于细菌对蛇纹石的风化，而添加一定量的蛇纹石也能促进细菌对方解石的风化，这些风化作用与细菌的酸溶作用及分泌的CA活性密切相关。矿物形态观察分析表明，细菌和矿物之间可以形成细菌-矿物复合体并导致细菌对矿物的风化，矿物组成分析表明矿物晶体结构已被细菌溶蚀破坏，研究结果显示细菌在蛇纹石和方解石矿物风化过程中发挥重要作用。2. 胶质芽孢杆菌-蛇纹石-方解石相互作用机理及对碳循环的影响研究：细菌在有N培养基中生长能产生高浓度的乙酸，最高达4384mg/L，说明该菌主要是通过分泌乙酸对矿物进行风化；而细菌在无N培养基中产生乙酸量少得多，最高为12.98mg/L，进一步实验表明，在无N培养基中细菌可通过分泌少量乙酸和丁酸酮等有机物质对矿物进行风化作用。说明酸溶作用无论在有氮和无氮条件下均对矿物风化起重要作用。由于试样HCO3-浓度的高低直接影响试样SICO2的大小，细菌作用矿物试样SICO2升高，说明在细菌风化蛇纹石和方解石的作用过程中试样溶液中CO2的量增大。水化学分析结果显示，试样中纤维蛇纹石、海泡石、云母、羟基磷灰石等矿物的风化和文石、方解石、白云石、菱锰矿、菱铁矿等碳酸盐矿物的生成趋势与试样SICO2升高密切相关，硅酸盐和碳酸盐矿物的风化以及碳酸盐矿物的形成都会吸收CO2。这些结果为碳素微生物固定研究提供新的思路和理论依据。3. 胶质芽孢杆菌-钾长石-方解石相互作用研究：与对照相比，细菌作用组pH值明显降低，释放的Ca2+浓度是对照组试样的16-20倍。有机代谢产物分析表明，细菌在风化钾长石和方解石矿物过程中产生了乙酸、乙酸甲酯、异丁酸和2-甲基丁酸等有机物，它们可对矿物进行风化作用。细菌对钾长石的风化作用程度较小，有N培养基条件和方解石的添加会促进细菌对钾长石的风化作用，这与试样中细菌分泌的CA活性有关，而细菌分泌的CA活性大小与细菌数量也密切相关。与细菌-蛇纹石-方解石试样的CA活性相比，细菌-钾长石-方解石试样的CA活性要低的多，反映了细菌在矿质营养较丰富的环境中生长较旺盛。细菌作用方解石较容易，其次是对蛇纹石的作用，细菌作用钾长石最困难。研究发现，适量的矿物养分会改变细菌的生长繁殖状况，导致试样pH值升高，易于微生物成矿作用。细菌易在钾长石表面附着，细菌在对钾长石和方解石矿物的作用过程中同时存在微生物风化矿物和微生物诱导成矿作用，体现了细菌与矿物相互作用之间的复杂关系。4. 胶质芽孢杆菌-钾长石-方解石相互作用机理及对碳循环的影响研究：有N培养基利于细菌-钾长石-方解石试样产生乙酸，无N培养基不利于细菌-钾长石-方解石试样产生乙酸。有N培养基中细菌-蛇纹石-方解石试样分泌的乙酸含量大约是细菌-钾长石-方解石试样分泌乙酸含量的5倍，说明矿物质养分丰富有利于细菌分泌乙酸。相对离子钾源（KCl），钾长石更能促进细菌产生CA活性，过多的K+会抑制CA活性。随着试样pH值的增加HCO3-浓度也会增加，试样SICO2也相应较大。试样SICO2升高同样体现了细菌风化钾长石和方解石作用过程试样溶液CO2的量增大。适量的矿物组成有利于细菌诱导生成次生矿物。水化学分析结果显示部分硅酸盐矿物在细菌及其分泌物的作用下进行风化作用，在细菌-钾长石-方解石相互作用试样中有形成碳酸盐矿物的趋势。硅酸盐和碳酸盐矿物的风化作用会吸收CO2，碳酸盐矿物的形成也需要吸收部分CO2，而细菌在碳素固定过程中起重要作用。综上所述，微生物-硅酸盐-碳酸盐矿物相互作用影响碳素循环，其中微生物起着非常重要的作用。该研究不仅发现了部分“遗漏的汇”，为完善碳循环模型作贡献，还有助于正确认识微生物生物地球化学过程对全球碳循环的贡献。; Microbes promote the weathering of silicate and carbonate minerals by metabolic acid and can release of CO2, the formation of carbonate minerals in terrestrial and aquatic environments also make CO2 fixation. The microbial carbon cycledriving effects contribute to understand the relationship between microbe and carbon cycle from inorganic carbon and organic carbon angle. And it provides new material for the relationship of the biogeochemical processes of carbon cycle and the evolution of earth's surface environment, so it has important research value.The paper studies microbe-silicate-carbonate minerals interactions and their effects on the carbon cycle, by setting the pure water and sterilization as control groups, as well as different nutrient conditions and different mineral content. The interactions between bacteria and minerals were analysed by determination of pH value, conductivity, carbonic anhydrase activity, the elements concentration, metabolites, morphology observation and mineral crystal structure. Explored the mechanism of bacterial weathering minerals by detecting 5-(hydroxymethyl) furfural, 2-hydroxy butyrate ketone, methyl acetate and methyl butyrate content, combination of HCO3-concentration, CO2 saturation index and mineral saturation index analysed the effect of bacteria-silicate-carbonate mineral interactions on the carbon cycle, which provided a feasible method and theoretical basis to carbon fixation.The main results are as follows:1. Bacillus mucilaginosus-serpentine-calcite interaction studies: The extent of the role of bacterial weathering of minerals in nitrogen medium is much larger than in nitrogen-free medium. The average pH was 7.44 in nitrogen-free medium, while the average pH was 6.19 in nitrogen medium, indicating that the bacteria weathered mineral through secreting of acidic organic matter, further analysis showed that the bacteria secrete large amounts of acetic acid in nitrogen medium. The study found that the appropriate amount of calcite added can improve the weathering of the serpentine by bacteria, while the appropriate amount of serpentine added also can improve the weathering of the calcite by the bacteria. These results are closely related to the bacterial acid-soluble and the CA activity. Morphological observation of the mineral analysis showed that the bacteria-mineral complex formed and lead to the weathering of minerals, mineral composition analysis showed that the crystal structure has been destroyed by bacteria. Compared with the sterilization control group, the results show that bacteria play an important role in the serpentine and calcite minerals weathering process.2. Bacillus mucilaginosus-serpentine-calcite interaction mechanism and its effect on the carbon cycle: the bacteria produce higher concentration of acetic acid (highest value is 4384mg/L) in nitrogen medium, which showed mineral weathering mainly through the acetic acid secreted by bacteria. Whereas bacteria produce less acetic acid (highest value is 12.98mg/L) in nitrogen-free medium, further experiments showed that mineral weathering in nitrogen-free medium for the acetic acid and butyric acid ketone secreted by bacteria, which means the role of acid-soluble plays an important role in mineral weathering. The concentration of HCO3- affects the SICO2 directly, and the SICO2 of bacteria-mineral specimens increased, indicating the CO2 increased in the process of bacterial weathering of serpentine and calcite. Water chemistry analysis showed that the chrysotile, sepiolite, mica, hydroxyapatite mineral weathered and aragonite, calcite, dolomite, rhodochrosite, siderite and other carbonate minerals generated trend, which related to SICO2 increased closely. Silicate and carbonate minerals weathering and carbonate minerals formation all adsorb the CO2. These results provide new ideas and theoretical basis for atmospheric carbon fixation.3. Bacillus mucilaginosus-K-feldspar-calcite interaction analysis: Compared with the control group, the pH values decreased significantly, and the Ca2+ concentration released by bacteria is more 16-18 times than that of the control group samples. The bacteria secreted acetic acid, methyl acetate, 2-methyl-propanoic acid and 2-methyl-butyric acid in the process of weathering of K-feldspar and calcite, these organic metabolites promoted mineral weathering. Bacterial weathering of K-feldspar had a lesser extent, nitrogen medium and calcite added promoted bacterial weathering of K-feldspar, which was closely related with CA activity and the growth of bacteria. The CA activity of bacteria-serpentine-calcite specimen is much higher than bacteria-K-feldspar-calcite specimen, reflecting the bacterial growth well in the mineral nutrient-rich environment. The study found that appropriate mineral nutrients can change the status of bacteria growth and reproduction, resulting in pH value increased and microbial mineralization. The bacteria attached to the K-feldspar surface easily. Microbial weathering of minerals and microbes induce mineralization occured simultaneously in bacteria-K-feldspar-calcite interaction, reflecting the relationship between bacteria and mineral.4. Bacillus mucilaginosus-K-feldspar-calcite interaction mechanism and its effect on the carbon cycle: The bacteria produced more acetic acid in nitrogen medium than in nitrogen-free medium in bacteria-K-feldspar-calcite interaction. The bacteria secreted more acetic acid in bacteria-serpentine-calcite interaction than in bacteria-K-feldspar-calcite interaction, the acid content is five times, which means bacteria secreted more acid in mineral nutrient-rich environment. K-feldspar can enhance bacteria secrete CA activity, compared to ion potassium source (KCl), excessive K+ can inhibite the CA activity. The HCO3- concentration and the SICO2 increased with the pH value increased. The SICO2 rise reflected the CO2 increase in the process of bacterial weathering of K-feldspar and calcite. Water chemistry analysis showed that part of silicate weathered for the secretions of bacteria, and some carbonate minerals formation in bacteria-K-feldspar-calcite interaction, which may absorb CO2 and the bacteria plays an important role in the carbon fixation.In summary, the microbe-silicate-carbonate mineral interactions affect the carbon cycle, in which bacteria play an important role. The study not only found a part of the "missing sink", and make contributions to improve the carbon cycle model, but also help to understand the contribution of microbial biogeochemical processes on the global carbon cycle. |
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