铜耐受定向驯化强化嗜酸喜温硫杆菌浸出贫黄铜矿

Directed Domestication of Copper Tolerance for Enhancing Lowgrade Chalcopyrite Bioleaching by Acidithiobacillus caldus

生物浸出贫黄铜矿后期,累积的Cu^2+会对微生物产生胁迫效应从而影响浸出效率,因此该类微生物的铜耐受性定向驯化变得非常关键。对嗜酸喜温硫杆菌(Acidithiobacillus caldus)进行6个月铜耐受定向驯化,将出发菌株与驯化菌株在不同铜胁迫浓度下(0、1和3g/LCu^2+)纯培养及浸出贫黄铜矿,并比较分析关键参数变化。在纯培养体系中,3g/LCu2+胁迫下最高比生长速率(μmax)由驯化前0.21d-1(13d)提升至0.54d-1(10d)。在0、1和3g/LCu^2+浸出体系中,菌株驯化后铜浸出率分别较出发菌株提高17.64%、70.93%及306.09%。扫描电镜(SEM)分析矿渣形貌差异表明伴随胁迫作用增强菌体对矿物腐蚀程度变弱,在相同铜胁迫水平下,驯化菌株浸出体系矿渣表面呈现更多潜在的吸附位点及明显腐蚀痕迹。采用傅里叶红外光谱(FTIR)分析矿渣表面关键官能团变化,驯化菌株浸出体系的矿渣呈现更多含硫基团。X射线衍射(XRD)分析矿渣成分表明驯化菌株浸出体系中呈现较为丰富的铁硫衍生物如Fe3O4、FeS。综上,驯化后A.caldus具备较强抵御铜胁迫能力,在浸出体系中保持了更活跃的生化浸出效应,有望在类似的工业生物浸出过程中发挥其潜在优势。

In the late stage of low-grade chalcopyrite bioleaching,the accumulated Cu2+ would inhibit the cell growth of bioleaching microorganisms and affect leaching efficiency,therefore,it is crucial to domesticate the copper tolerance of bioleaching microorganisms. After 6 months copper tolerance domestication of Acidithiobacillus caldus,the key parameters of the original strain and the domesticated strain in the pure culture and bioleaching process under different copper stress(0,1 and 3 g/L Cu^2+)were analyzed. The highest specific growth rate (μmax)in pure culture under 3 g/L Cu^2+ stress increased from 0.21 d^-1(13 d)before domestication to 0.54 d^-1(10 d). The efficiencies of copper leaching by the domesticated strain in 0,1 and 3 g/L Cu^2+ leaching system increased by 17.64%,70.93% and 306.09% respectively, compared to the original one. The morphological observation of the leached slag by scanning electron microscopy(SEM)indicated that the degree of corrosion reduced along with the increased copper stress. Under the same stress conditions,the slag from domesticated leaching system presented more potential adsorption sites and obvious corrosion marks. Fourier transform infrared spectroscopy(FTIR)analysis of key functional groups showed that there were more sulfur-containing groups in the slags of domesticated leaching system. X-ray diffraction(XRD) analysis of slag composition implied that these derivatives in iron and sulfur elements such as Fe3O4 and FeS in the domesticated bioleaching system were rich. In sum,the domesticated A. caldus has strong resistance to copper stress and maintains a more active biochemical leaching effect in leaching system,which is expected to play a potential advantage in the similar industrial bioleaching process.