摘要
      微生物电解池（MECs）被广泛认为是降解抗生素的有前途的替代品。作为MECs的主要操作参数之一，电压可能会影响抗生素抗性基因（ARGs）的传播，因为它会影响细菌的生理特性。然而，人们对电压对MECs中细菌突变加速和ARG通过水平转移传播的影响知之甚少。在这项研究中，施加两个电压（0.9 V和1.5 V）来确定电刺激是否会增加细菌突变频率。使用三个电压（0.9V、1.5V和2.5V）来评估编码ARGs的质粒在MECs中从供体（大肠杆菌K-12）到受体（大肠杆菌HB101）的偶联转移频率。在MECs中重复传代10天后，大肠杆菌K-12的突变频率提高，因此产生的突变体对四环素的抗性更强。当电压高于0.9V时，在阳极室中，偶联ARG的转移频率显著增加（p<0.05）。在电刺激下，活性氧（ROS）的过度产生（电压＞0.9V）和细胞膜通透性（电压＞1.5V）显著增加（p>0.05）。全基因组RNA测序表明，与氧化应激和细胞膜相关的基因表达随着暴露于电刺激而上调。电刺激诱导氧化反应，从而触发MECs中供体和受体的ROS过度产生、SOS反应和细胞膜通透性增强。这些发现为电压在MECs中ARGs的产生和传播中的潜在作用提供了见解。
Abstract
Microbial electrolysis cells (MECs) are widely considered as promising alternatives for degrading antibiotics. As one of the major operating parameters in MECs, voltage might affect the spread of antibiotic resistance genes (ARGs) given it can affect the physiological characteristics of bacteria. However, little is known about the impacts of voltage on the acceleration of bacterial mutation and the promotion of ARG dissemination via horizontal transfer in MECs. In this study, two voltages (0.9 V and 1.5 V) were applied to identify if electrical stimulation could increase bacterial mutation frequency. Three voltages (0.9 V, 1.5 V, and 2.5 V) were used to evaluate the conjugative transfer frequency of plasmid-encoded the ARGs from the donor (E. coli K-12) to the recipient (E. coli HB101) in MECs. After repeating subculture in MECs for 10 days, the mutation frequency of E. coli K-12 was promoted, consequently, the generated mutants became more resistant against tetracycline. When the voltage was higher than 0.9 V, conjugative ARG transfer frequency was significantly increased in the anode chamber (p < 0.05). The over-production of reactive oxygen species (ROS) (voltage >0.9 V) and cell membrane permeability (voltage >1.5 V) were significantly enhanced under electrical stimulations (p < 0.05). Genome-wide RNA sequencing indicated that the expressions of genes related to oxidative stress and cell membrane were upregulated with exposure to electrical stimulation. Electrical stimulations induced oxidative reactions, which triggered ROS over-production, SOS response, and enhancement of cell membrane permeability for both donor and recipient in the MECs. These findings provide insights into the potential role of voltage in the generation and spread of ARGs in MECs.

https://www.sciencedirect.com/science/article/abs/pii/S0045653521031751