黑曲霉及其代谢产物对花岗岩风化作用的影响

Effect of Aspergillus niger and its metabolites on weathering of granite

【目的】为揭示微生物风化岩石的机理,促进土壤的形成和岩石边坡覆绿,改善生态环境,笔者研究了黑曲霉(Aspergillus niger)及代谢产物对花岗岩风化作用的影响。【方法】从花岗岩风化土壤中分离、纯化得到一株高效风化黑曲霉菌株,采用摇瓶实验和电镜分析,研究黑曲霉在发酵过程中产生代谢产物的种类及其对花岗岩中硅、铁、铝、钠等元素的浸出效果。【结果】在含有花岗岩粉的培养基中,黑曲霉发酵液中合成的6种有机酸(草酸、酒石酸、琥珀酸、苹果酸、乙酸、柠檬酸)的含量在发酵初期逐渐升高,在发酵后期随着发酵时间的延长而逐渐降低;在不同发酵期合成的氨基酸种类不同。含花岗岩粉的培养基有利于黑曲霉大量合成多糖类物质。黑曲霉代谢产物摇瓶实验表明,有机酸、氨基酸、多糖等均可破坏岩石结构,并释放出硅、铁、铝、钠等元素。在岩石风化时,代谢产物具有协同作用,黑曲霉风化花岗岩效果最优,有机酸、氨基酸、多糖混合物浸出元素的效果又明显优于它们各自单独作用时的效果。【结论】黑曲霉及其代谢产物有机酸、氨基酸、多糖以及三者混合物都具有风化岩石的作用,且黑曲霉风化岩石的效果优于单一和混合代谢产物。

【Objective】To reveal the mechanism of microbial weathering of rocks,promote the rock slope to covered with plants,and improve the ecosystem,the effect of Aspergillus niger and its metabolites on the weathering of granite were studied in this research.【Method】An A.niger strain,which is highly efficient in weathering rocks,was isolated and purified from the granite soil.Liquid dynamic culture and electron microscopic analysis were used to study the metabolites produced by A.niger during the fermentation.Effects of the metabolites on leaching of silicon,iron,aluminum,and other elements from granite were studied.【Result】The results indicated that A.niger in the medium containing granite powder can synthesize six kinds of organic acids,including oxalic acid,tartaric acid,succinic acid,malic acid,acetic acid,and citric acid in its fermentation liquors.The contents of these organic acids gradually increased at early stage of fermentation,and then decreased with the fermentation process.Which indicated that A.niger could uptake and utilization those organic acids during growth and reproduction.A.niger synthesizes different amino acids in different fermentation stages,and the medium containing granite powder is beneficial in synthesizing polysaccharides.The results of metabolites of A.niger in liquid dynamic culture indicate that organic acid,amino acid,and polysaccharides can destroy the structure of rocks and release silicon,iron,aluminum,sodium,and other elements from granite.During rock weathering,the metabolites have certain synergistic effect.The effect of the mixture of organic acids,amino acids,and polysaccharides on elements extractions is significantly better than their respective effects.【Conclusion】A.niger and its metabolites,including organic acids,amino acids,and polysaccharides,and their mixture facilitate the weathering of granite,and the effect of weathering granite by A.niger is superior to that of single and mixed metabolites.