Geomicrobiology, Institute of Metallurgy, UASLP, Sierra Leona 550, Lomas 2°, 78210, San Luis Potosí, SLP, Mexico.
Appl Microbiol Biotechnol. 2012 Jan;93(2):763-75. doi: 10.1007/s00253-011-3465-2. Epub 2011 Jul 20.
We have applied epifluorescence principles, atomic force microscopy, and Raman studies to the analysis of the colonization process of pyrite (FeS(2)) by sulfuroxidizing bacteria Acidithiobacillus thiooxidans after 1, 15, 24, and 72 h. For the stages examined, we present results comprising the evolution of biofilms, speciation of S (n) (2-) /S(0) species, adhesion forces of attached cells, production and secretion of extracellular polymeric substances (EPS), and its biochemical composition. After 1 h, highly dispersed attached cells in the surface of the mineral were observed. The results suggest initial non-covalent, weak interactions (e.g., van der Waal's, hydrophobic interactions), mediating an irreversible binding mechanism to electrooxidized massive pyrite electrode (eMPE), wherein the initial production of EPS by individual cells is determinant. The mineral surface reached its maximum cell cover between 15 to 24 h. Longer biooxidation times resulted in the progressive biofilm reduction on the mineral surface. Quantification of attached cell adhesion forces indicated a strong initial mechanism (8.4 nN), whereas subsequent stages of mineral colonization indicated stability of biofilms and of the adhesion force to an average of 4.2 nN. A variable EPS (polysaccharides, lipids, and proteins) secretion at all stages was found; thus, different architectural conformation of the biofilms was observed during 120 h. The main EPS produced were lipopolysaccharides which may increase the hydrophobicity of A. thiooxidans biofilms. The highest amount of lipopolysaccharides occurred between 15-72 h. In contrast with abiotic surfaces, the progressive depletion of S (n) (2-) /S(0) was observed on biotic eMPE surfaces, indicating consumption of surface sulfur species. All observations indicated a dynamic biooxidation mechanism of pyrite by A. thiooxidans, where the biofilms stability and composition seems to occur independently from surface sulfur species depletion.
我们将荧光原理、原子力显微镜和拉曼研究应用于分析 1、15、24 和 72 小时后硫化亚铁（FeS2）被硫氧化菌氧化亚铁硫杆菌（Acidithiobacillus thiooxidans）定殖的过程。对于检查的阶段，我们提出了包含生物膜的演变、S(n)(2-)/S(0)物种的形态、附着细胞的粘附力、细胞外聚合物（EPS）的产生和分泌及其生化组成的结果。在 1 小时时，在矿物表面观察到高度分散的附着细胞。结果表明，初始的非共价、弱相互作用（例如范德华力、疏水力）介导了对电氧化的块状黄铁矿电极（eMPE）的不可逆结合机制，其中单个细胞的初始 EPS 产生是决定性的。矿物表面在 15 到 24 小时之间达到最大细胞覆盖率。更长的生物氧化时间导致矿物表面的生物膜逐渐减少。附着细胞粘附力的定量表明初始机制很强（8.4 nN），而随后的矿物定殖阶段表明生物膜的稳定性和对平均 4.2 nN 的粘附力稳定。在所有阶段都发现了可变的 EPS（多糖、脂质和蛋白质）分泌；因此，在 120 小时期间观察到生物膜的不同结构构象。产生的主要 EPS 是脂多糖，这可能会增加氧化亚铁硫杆菌生物膜的疏水性。脂多糖的含量在 15-72 小时之间最高。与非生物表面相反，在生物 eMPE 表面上观察到 S(n)(2-)/S(0)的逐渐耗尽，表明表面硫物种的消耗。所有观察结果表明氧化亚铁硫杆菌对黄铁矿的动态生物氧化机制，其中生物膜的稳定性和组成似乎独立于表面硫物种的消耗而发生。
