高效矿物风化细菌假单胞菌风化黑云母的生理机制初探
毕业论文关键词：假单胞菌；黑云母；矿物风化；细菌吸附
Study on Biotite-Weathering Physiological Mechanism by Mineral-Weathering Bacteria Pseudomonas
Abstract：Microbial weathering is the most important way of rock weathering on earth. In this study, the phenomenon that the decomposition of biotite by Pseudomonas was studied to make out the physiological mechanism of microbial weathering. Two strains of Pseudomonas sp. S4 and E229 with distinct mineral-weathering effect were selected after purified step by step, identified by 16S rDNA sequence analysis and tested by 7 days shake flask. In the 15-day dynamic shake flask test, the pH value of the two strains’ fermentation liquid was between 3 and 4, which was significantly lower than the control. The content of Si and Al in fermentation liquid continued to accumulate and hold an upward trend all the time. The changing of Fe in fermentation liquid was different from them, its content increased first, then decreased and increased once again. The polysaccharide content in the fermentation liquid of strain E229 was always higher than that of strain S4. The number of bacteria adsorbed on the mineral surface in the fermentation liquid of strain S4 was increasing as time goes on, and E229 was decreasing. In conclusion, strain S4 and strain E229 dissolved biotite by reducing pH, adsorbing on mineral surface and producing exopolysaccharides. However, they played a different role during the mineral weathering process.
Key words: Pseudomonas; biotite; mineral weathering; bacterial adsorption
目 录
摘要3
关键词3
Abstract 3
Key words 3
引言（或绪论）3
1 材料与方法 4
1.1 材料 4
1.2 方法 5
1.2.1 可培养细菌的分离、纯化 5
1.2.2 供试菌株的分子鉴定 5
1.2.3 各供试菌株对黑云母的溶解效果 5
1.2.4 两株高效假单胞菌菌株风化黑云母的动态试验 6
2 结果与分析 7
2.1 可培养细菌的分离、纯化 7
2.2 供试菌株的分子鉴定 8
2.3 矿物风化细菌的筛选 8
2.4 两株高效假单胞菌菌株风化黑云母的动态试验10
3 讨论13
4 结束语14
致谢 14
参考文献 14
附录 A 矿物组成15
附录B 各菌株16S rDNA 序列 15
矿物-微生物相互作用是形成我们地球岩石圈的一个关键因素，微生物风化硅酸盐矿物的方式在自然界中普遍存在[1]。由于微生物对代谢方面的需求，驱动了微生物风化矿物、释放元素的行为，在满足自己对能量和营养物质需求的同时，还深刻影响着土壤的发育，甚至影响着地球的生态[2-3]。有研究发现细菌在外界提供的寡营养条件下，能够通过从黑云母中溶解 Fe 元素来响应 Fe元素的不足，并使用生物膜基质等手段来增强对矿物的风化，从而释放阳离子获得营养物质[4]。 黑云母是土壤中常见的硅酸盐矿物，为土壤中 K，Si，Al，Fe等元素的增加提供了重要来源[5-6]。尽管地壳中的硅铝铁含量丰富，但大部分为非有效态，不能被植物直接吸收利用[7]。 已有的对假单胞菌的报道多关于其形成生物膜在生物修复、临床等方面的贡献[8]，对其风化矿物的研究报道较少。本研究利用从实验室保藏菌株中分离纯化、鉴定、筛选后得到的两株具较强矿物风化能力的细菌 Pseudomonas sp. S4 菌株和 Pseudomonas sp. E229 菌株，通过动态摇瓶试验对发酵液的pH值，Si、Al、Fe 元素的溶解情况，多糖含量， 细菌在矿物表面的吸附情况等进行测定， 研究该两株假单胞菌对黑云母的风化效果，初步阐明其风化黑云母的生理机制，以期为发展环保农业、创新生物技术提供理论依据和实验材料。
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