沙芬西芽孢杆菌HR-2菌株对粗面岩的风化作用

Experiments on effects of Bacillus safensis strain HR-2 on trachyte weathering

岩石(矿物)风化是在地球关键带内发生的最重要地球化学过程之一,其对土壤发生和演化、营养元素循环等过程都具有重要的影响.以沙芬西芽孢杆菌(Bacillus safensis)HR-2菌株为微生物材料,在硅酸盐细菌专性培养基中进行了为期60d的粗面岩风化实验.利用X射线衍射仪(XRD)和扫描电子显微镜分别对不同阶段固相产物的矿物组成、表面形貌及元素组成进行了观察与测定,用高效液相色谱仪和电感耦合等离子体发射光谱仪分别测定了相应阶段培养液中的低分子量有机酸和主要元素(Si,Al,Fe,Mg,K和Ca)的含量.结果表明,HR-2菌株可显著促进粗面岩的风化,释放出Si,Al,Fe,Mg,K和Ca等元素,各元素的最大溶出率(%)分别为:Ca(10.00)>Fe(4.90)>Mg(4.80)>K(2.27)>Al(0.36)>Si(0.15).HR-2菌株可能是通过代谢产酸、降低环境pH而促进了粗面岩的风化.最重要的结果是,在XRD图谱中发现了新形成的次生矿物——高岭石和伊利石的证据.

Rock（mineral）weathering is one of the most important geochemical processes occurring on the Earth＇s critical zone,and it has a significant influence on soil occurrence and evolution,nutrient cycling and so on.In this60-days experiment,Bacillus safensis HR-2 strain was used as the bacterial culture medium to understand its effects on chemical weathering of trachyte.The mineralogical compositions,surface morphology and elemental compositions of the solid products were observed and measured by X-Ray Diffraction（XRD）and scanning electron microscope,respectively.Leach solution was measured by inductively coupled plasma optical emission spectrometry for elements（Si,Al,Fe,Mg,K and Ca）that released from weathering of trachyte.The concentrations of low molecular weight organic acids were measured by high performance liquid chromatograph.The results showed that HR-2 strain promoted the weathering of trachyte significantly and released Si,Al,Fe,Mg,K,and Ca.The maximum dissolution rate（%）of each element with an order of Ca（10.00）〉Fe（4.90）〉Mg（4.80）〉K（2.27）〉Al（0.36）〉Si（0.15）.HR-2 strain may promote the weathering of trachyte via pH decrease by producing acid.One of the most important observations of this experiment is the discovery of newly formed secondary minerals-kaolinite and illite identified in the XRD patterns.