微生物对绿脱石中有机质利用的研究

The Utilization of Organic Matters in Nontronite by Microorganisms

为了探索黏土矿物中含有的有机质能否被微生物利用以及微生物利用的效率,本文选取富三价铁的黏土矿物绿脱石NAu-2为还原对象,嗜热菌Thermus scotoductus SA-01,以及常温菌Shewanella putrefaciens CN-32为异化铁还原菌,分别在没有外加碳源的情况下对NAu-2结构铁进行还原。实验选取化学方法来测试Fe3+还原程度与还原速率,利用X射线粉晶衍射(XRD)、傅里叶转换红外光谱分析仪(FTIR)、扫描电镜(SEM)对黏土矿物还原产物进行矿物学表征,利用总碳/氮分析仪测试黏土矿物释放出来的溶解碳总量以及高效液相色谱仪来分析不同有机组分的含量。实验结果表明相对于常温菌CN-32,嗜热菌SA-01可以有效利用绿脱石中含有的微量有机质作为碳源。由此可知,黏土矿物经微生物作用后发生还原溶解,其吸附的有机质会随着溶解程度的升高不断释放到周围环境中;黏土矿物含有的有机质组分成分复杂,在不同温度环境下释放出来的有机质速率与种类有所不同。

In this work, the utilization of organic matters in clay minerals by microorganisms was investigated. Thermophilic bacteria Thermus scotoductus SA-01 and mesophilic bacteria Shewanella putrefaciens CN-32 were selected to reduce structural Fe^3＋ in the nontronite NAu-2 without other carbon source. The rate and extent of Fe^3＋ bioreduction were measured by chemical methods. Bioreduced NAu-2 was characterized with X-ray powder diffraction （XRD） , Fourier transform infra- red spectroscopy （FTIR） and scanning electron microscopy （SEM） to investigate mineralogical changes as a result of microbial activity. The amount of total organic carbon released from NAu-2 was determined by an N/C analyzer and the con- centrations of different organic compounds released from NAu-2 were measured by high performance liquid chromatography （ HPLC）. Experimental results demonstrated that ： compared with ShewaneUa putrefaciens CN-32, Thermus scotoductus SA- 01 can effectively use organic matter in NAu-2 as the carbon source.We concluded that the reductive dissolution happens when structural Fe^3＋ in clay minerals is being reduced by microbes. The organic matter associated with nontronite is released into the aqueous solution due to reductive dissolution of nontronite. The organic compounds released from clay minerals are complicated, the rate and the type of organic compound released into solution differ under different temperatures.