铜离子胁迫对嗜铁钩端螺旋菌生理特性的影响

Effects of Copper Stress on Physiological Characteristics of Leptospirillum ferriphilum

研究铜离子胁迫对嗜铁钩端螺旋菌ML-04生理特性的影响。以野生菌嗜铁钩端螺旋菌ML-04和驯化菌嗜铁钩端螺旋菌ML-04-ADP为材料,比较吸附及胞内的总铜含量,驯化菌对闪锌矿的吸附率、zeta电位、傅立叶变换红外光谱、疏水性和氨基酸组成的影响。结果表明:初始时,驯化菌吸附及胞内总铜含量明显高于野生菌,在0.5 mol·L-1 CuSO4培养基中培养1h后,驯化菌增加的铜也远比野生菌多,当将驯化菌放入到无铜培养基中培养1h后,总铜含量又显著减少;驯化菌对闪锌矿的吸附率提高了20.76%,驯化菌的等电点从野生菌的4.0提高到5.0。FT-IR结果表明,驯化菌表面产生了更多的蛋白物质,疏水性增强;正十六烷-9K培养基两相分层试验表明,驯化菌和野生菌水相中菌体的数量分别减少了14%和2%;氨基酸组成分析表明,两株菌的蛋白在种类上是有差别的。在高浓度铜离子环境下,驯化菌表面产生更多的蛋白物质,使细菌的疏水性增强,细胞表面的电荷数和等电点发生变化。在pH值2.0时,驯化菌表面带的正电荷大于野生菌,此时闪锌矿带负电荷。静电引力和疏水性的共同作用使驯化菌对闪锌矿的吸附能力大于野生菌对闪锌矿的吸附能力。

To study the effects of copper stress on the physiological characteristics of Leptospirillum ferriphilum ML-04. The wild type L.ferriphilum ML-04 and adapted L.ferriphilum ML-04-ADP cells were cultured under copper stress, respectively, then,the membrane bound and intracellular copper iron contents, the adsorption rate to sphalerite, the Zeta-potentials, the FF-IR, the hydrophobicity, as well as the amino acid components of the intracellular protein hydrolytes were measured for the wild type and adapted cells.The results showed that the membrane bound and intracellular copper of adapted cells is higher than the wild type microbial cells in the initial. After 1 hour, more copper was adsorbed by adapted cells compared to the wild type microbial cells. The adsorption of the adapted cells to sphalerite was increased by 20.76% compared with the wild type microbial cells. The isoelectric point of the adapted strain （pI=5.0）was higher than the wild strain （pI=4.0）. FT-IR analysis suggested that more proteins were synthesized by the adapted microbial cells., The hexadecane-gK two-phase partition test showed that the adapted cells were more hydrophobic than the wild type cells, with the cell number in the water phase reduced by 14% and 2%,respectively. Amino acid analysis of wild and adapted microbial cells suggested that the amino acid composition of the proteins was different. Under copper stress, the adapted cells synthesized more proteins on the cell surface, which made them more hydrophobic and changed the cell surface charges. At pH 2.0, more positive electrical charges existed on the cell surface of the adapted cells, while sphalerite had negative electrical charges. The increased forces of static electrical attraction and the hydrophobic effect enabled the adapted cells to have higher adsorbing ability onto sphalerite compared with the wild type cells.