Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico.
CONACYT, Ciudad de México, Mexico.
Appl Microbiol Biotechnol. 2020 May;104(9):4059-4069. doi: 10.1007/s00253-020-10502-5. Epub 2020 Mar 16.
Geobacter sulfurreducens is capable of reducing Pd(II) to Pd(0) using acetate as electron donor; however, the biochemical and genetic mechanisms involved in this process have not been described. In this work, we carried out transcriptome profiling analysis to identify the genes involved in Pd(II) reduction in this bacterium. Our results showed that 252 genes were upregulated while 141 were downregulated during Pd(II) reduction. Among the upregulated genes, 12 were related to energy metabolism and electron transport, 50 were classified as involved in protein synthesis, 42 were associated to regulatory functions and transcription, and 47 have no homologs with known function. RT-qPCR data confirmed upregulation of genes encoding PilA, the structural protein for electrically conductive pili, as well as c-type cytochromes GSU1062, GSU2513, GSU2808, GSU2934, GSU3107, OmcH, OmcM, PpcA, and PpcD under Pd(II)-reducing conditions. ΔpilA and ΔpilR mutant strains showed 20% and 40% decrease in the Pd(II)-reducing capacity, respectively, as compared to the wild type strain, indicating the central role of pili in this process. RT-qPCR data collected during Pd(II) reduction also confirmed downregulation of omcB, omcC, omcZ, and omcS genes, which have been shown to be involved in the reduction of Fe(III) and electrodes. The present study contributes to elucidate the mechanisms involved in Pd(II) reduction by G. sulfurreducens. Graphical Abstract KEY POINTS: • Transcriptome analysis provided evidence on Pd(II) reduction by G. sulfurreducens. • Results indicate that electrically conductive pili is involved in Pd(II) reduction. • G. sulfurreducens was not able to grow under Pd(II)-reducing conditions. • The study contributes to a better understanding of the mechanisms in Pd(II) reduction.
脱硫弧菌能够利用乙酸作为电子供体将 Pd(II)还原为 Pd(0)；然而，该过程涉及的生化和遗传机制尚未被描述。在这项工作中，我们进行了转录组谱分析，以鉴定该细菌中参与 Pd(II)还原的基因。我们的结果表明，在 Pd(II)还原过程中，有 252 个基因上调，141 个基因下调。在上调的基因中，有 12 个与能量代谢和电子传递有关，50 个与蛋白质合成有关，42 个与调控功能和转录有关，47 个与已知功能无同源基因。RT-qPCR 数据证实，在 Pd(II)还原条件下，编码 PilA（电导率菌毛的结构蛋白）以及 c 型细胞色素 GSU1062、GSU2513、GSU2808、GSU2934、GSU3107、OmcH、OmcM、PpcA 和 PpcD 的基因上调。与野生型菌株相比，ΔpilA 和 ΔpilR 突变株的 Pd(II)还原能力分别降低了 20%和 40%，表明菌毛在该过程中起核心作用。在 Pd(II)还原过程中收集的 RT-qPCR 数据还证实了 omcB、omcC、omcZ 和 omcS 基因的下调，这些基因已被证明参与了 Fe(III)和电极的还原。本研究有助于阐明脱硫弧菌还原 Pd(II)的机制。
