Study on mechanism of electroactive microorganisms response to 2,4-DCP

Abstract

The response of electroactive microorganisms (EAM) to toxic substances has attracted extensive attention. The path of electron transfer has been reported, but the mechanism of electrical signals decline after adding toxic substances is not clear yet. It was found that the shedding of the attached microorganisms was consistent with the decrease voltage after 2,4-DCP administration. Therefore, this study analyzed the mechanism of microorganisms in the presence of 2,4-DCP linking to the metabolic activity, the resistance of microbial defense to severe environment, and genomics means. The metabolic activity of microorganisms were discussed with adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD(H)), and dehydrogenases (DHA), which were decreased by 90 %, 96 %, and 19 %, respectively. The ability to resist damage caused by 2,4-DCP was mainly reflected in the early stage. The superoxide dismutase (SOD) and catalase (CAT) activities increased by 1.5 times and 60 times respectively, while the glutathione peroxidase (GSH-Px) was not significantly effected. The change of malondialdehyde (MDA) content showed that lipid peroxidation occurred in the early stage, which was closely related to the rapid decline of electrical signal. The expression of rpoE gene, associated with transcriptional regulation in microorganisms, increased significantly (p ≤ 0.001) from 0.3 % to 0.8 %, and that of the transmembrane protein gene mcp, responsible for the synthesis and transmission of signals, decreased significantly (p < 0.001) from 0.9 % to 0.2 %. All the detection results suggested that electroactive microorganisms were not reusable for warning of some toxic substances such as 2,4-DCP with high concentration in practical application.