Department of Chemical and Petroleum Engineering, University of Calgarygrid.22072.35, Calgary, Alberta, Canada.
Department of Biological Sciences, University of Calgarygrid.22072.35, Calgary, Alberta, Canada.
Appl Environ Microbiol. 2022 Jun 28;88(12):e0058022. doi: 10.1128/aem.00580-22. Epub 2022 May 31.
The growth of sulfate-reducing bacteria (SRB) and associated hydrogen sulfide production can be problematic in a range of industries such that inhibition strategies are needed. A range of SRB can reduce metal ions, a strategy that has been utilized for bioremediation, metal recovery, and synthesis of precious metal catalysts. In some instances, the metal remains bound to the cell surface, and the impact of this coating on bacterial cell division and metabolism has not previously been reported. In this study, Desulfovibrio desulfuricans cells (1g dry weight) enabled the reduction of up to 1500 mmol (157.5 g) palladium (Pd) ions, resulting in cells being coated in approximately 1 μm of metal. Thickly coated cells were no longer able to metabolize or divide, ultimately leading to the death of the population. Increasing Pd coating led to prolonged inhibition of sulfate reduction, which ceased completely after cells had been coated with 1200 mmol Pd gdry cells. Less Pd nanoparticle coating permitted cells to carry out sulfate reduction and divide, allowing the population to recover over time as surface-associated Pd diminished. Overcoming inhibition in this way was more rapid using lactate as the electron donor, compared to formate. When using formate as an electron donor, preferential Pd(II) reduction took place in the presence of 100 mM sulfate. The inhibition of important metabolic pathways using a biologically enabled casing in metal highlights a new mechanism for the development of microbial control strategies. Microbial reduction of sulfate to hydrogen sulfide is highly undesirable in several industrial settings. Some sulfate-reducing bacteria are also able to transform metal ions in their environment into metal phases that remain attached to their outer cell surface. This study demonstrates the remarkable extent to which Desulfovibrio desulfuricans can be coated with locally generated metal nanoparticles, with individual cells carrying more than 100 times their mass of palladium metal. Moreover, it reveals the effect of metal coating on metabolism and replication for a wide range of metal loadings, with bacteria unable to reduce sulfate to sulfide beyond a specific threshold. These findings present a foundation for a novel means of modulating the activity of sulfate-reducing bacteria.
硫酸盐还原菌 (SRB) 的生长和相关的硫化氢产生会在一系列行业中产生问题，因此需要抑制策略。 多种硫酸盐还原菌可以还原金属离子，这种策略已被用于生物修复、金属回收和贵金属催化剂的合成。 在某些情况下，金属仍与细胞表面结合，而这种涂层对细菌细胞分裂和代谢的影响以前尚未报道过。 在这项研究中，脱硫弧菌（1g 干重）能够还原多达 1500mmol（157.5g）钯（Pd）离子，导致细胞表面被约 1μm 的金属覆盖。 厚厚的涂层细胞不再能够代谢或分裂，最终导致种群死亡。 增加 Pd 涂层会导致硫酸盐还原的抑制时间延长，当细胞被 1200mmol Pd gdry 细胞涂层覆盖时，抑制完全停止。 较少的 Pd 纳米颗粒涂层允许细胞进行硫酸盐还原和分裂，随着表面相关的 Pd 减少，种群随着时间的推移得以恢复。 与使用甲酸盐相比，以乳酸作为电子供体，以这种方式克服抑制作用更快。 当使用甲酸盐作为电子供体时，在存在 100mM 硫酸盐的情况下，会优先发生 Pd(II)还原。 在金属中使用生物赋予的外壳来抑制重要的代谢途径突出了开发微生物控制策略的新机制。 在几种工业环境中，微生物将硫酸盐还原为硫化氢是非常不可取的。 一些硫酸盐还原菌还能够将环境中的金属离子转化为仍附着在其外细胞表面的金属相。 这项研究表明，脱硫弧菌可以被局部生成的金属纳米颗粒覆盖到何种程度，单个细胞携带的钯金属质量超过 100 倍。 此外，它揭示了金属涂层对代谢和复制的影响，对于广泛的金属负载，当细菌的硫酸盐还原作用不能超过特定的阈值时，细菌就不能将硫酸盐还原为硫化物。 这些发现为调节硫酸盐还原菌活性提供了新的基础。
