International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Center for Sensor and Actuator Material, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Molecules. 2020 Jul 9;25(14):3141. doi: 10.3390/molecules25143141.
The development of a simple and direct assay for quantifying microbial metabolic activity is important for identifying antibiotic drugs. Current production capabilities of environmental bacteria via the process called extracellular electron transport (EET) from the cell interior to the exterior is well investigated in mineral-reducing bacteria and have been used for various energy and environmental applications. Recently, the capability of human pathogens for producing current has been identified in different human niches, which was suggested to be applicable for drug assessment, because the current production of a few strains correlated with metabolic activity. Herein, we report another strain, a highly abundant pathogen in human oral polymicrobial biofilm, , to have the current production capability associated with its metabolic activity. It showed the current production of 50 nA/cm at OD of 0.1 with the working electrode poised at +0.4 V vs. a standard hydrogen electrode in a three-electrode system. The addition of antibiotics that suppress the microbial metabolic activity showed a significant current decrease (>90%), establishing that current production reflected the cellular activity in this pathogen. Further, the metabolic fixation of atomically labeled C (31.68% ± 2.26%) and N (19.69% ± 1.41%) confirmed by high-resolution mass spectrometry indicated that cells were metabolically active on the electrode surface. The identified electrochemical activity of shows that this can be a simple and effective test for evaluating the impact of antibacterial compounds, and such a method might be applicable to the polymicrobial oral biofilm on electrode surfaces, given four other oral pathogens have already been shown the current production capability.
开发一种简单直接的方法来定量检测微生物代谢活性对于鉴定抗生素药物非常重要。目前，通过细胞内到细胞外的称为细胞外电子传递（EET）的过程来研究环境细菌的生产能力在矿物还原细菌中得到了很好的研究，并已用于各种能源和环境应用。最近，已经在不同的人体生态位中鉴定出了人类病原体产生电流的能力，这被认为可用于药物评估，因为少数菌株的电流产生与代谢活性相关。在此，我们报告了另一种菌株，它是人类口腔多微生物生物膜中高度丰富的病原体， ，具有与代谢活性相关的电流产生能力。在三电极系统中，工作电极在+0.4 V 相对于标准氢电极偏置时，在 OD 值为 0.1 时显示出 50 nA/cm 的电流产生。添加抑制微生物代谢活性的抗生素会导致电流显著下降（>90%），这表明电流产生反映了该病原体的细胞活性。此外，通过高分辨率质谱证实的原子标记 C（31.68%±2.26%）和 N（19.69%±1.41%）的代谢固定进一步表明， 细胞在电极表面具有代谢活性。 所鉴定的电化学活性表明，这可以是评估抗菌化合物影响的简单有效测试，并且鉴于其他四种口腔病原体已经显示出电流产生能力，这种方法可能适用于电极表面的多微生物口腔生物膜。
