Effects of an external magnetic field on microbial functional genes and metabolism of activated sludge based on metagenomic sequencing

Abstract

This study explored the effect of 70-mT magnetic field on wastewater treatment capacity for activated sludge in long-term laboratory-scale experiments. Metagenomic sequencing were conducted based on Illumina HiSeq 2000 platform after DNA extraction of the activated sludge. Then the effect of the magnetic field on the microbial unigene and metabolic pathways in activated sludge was investigated. As a result, higher pollutant removal was observed at 70 mT, with which the elimination of total nitrogen (TN) was the most effective. Functional genes annotated based on eggNOG database showed that unigenes related to information storage and processing were enhanced by the magnetic field. For CAZy classification, category such as glycosyl transferases was more abundant in the reactor with magnetic field, which has been shown to promote the entire energy supply pathway. Additionally, in the KEGG categories, unigenes related to signaling molecules and interaction were significantly inhibited. Through the enrichment analysis of the nitrogen metabolism pathway, the magnetic field inhibited anabolic nitrate reduction by significantly inhibiting enzymes such as [EC:1.

Effect of an Electromagnetic Field on Anaerobic Digestion: Comparing an Electromagnetic System (ES), a Microbial Electrolysis System (MEC), and a Control with No External Force

“…This is because the use of a magnetic field can enhance the way the system performs physically to solid–liquid separation due to the clustering of colloidal particles. Additionally, the use of magnetic fields can affect the biological properties due to the enhancement of the bacterial activity, which increased the current density of the ES [ 19 , 38 ]. However, the higher intensity and the longer exposure duration after day 8 reduced the current density of the ES, which consequently reduced the biogas accumulation ( Figure 1 ).…”

“…Currently, researchers are trying to improve the performance of the traditional anaerobic digestion process, mainly because the process has low contaminant removal levels, low microbial activity, and low methane production. The use of an electromagnetic field together with the anaerobic digestion process has been shown to have a great deal of potential due to the greater enhancement of bacterial activity and the higher methane production [ 19 , 20 ]. Interestingly, current studies have shown a more positive effect for the use of a bioelectrochemical system in anaerobic digestion; the use of a bioelectrochemical system enhances the biological activity as well as the electrochemical efficiencies.…”

“…However, some studies have found that higher magnetic fields result in a blockage of the current density [ 29 ]. Factors such as the type of magnetic field, the intensity, the exposure time, and the cell wall can either improve or reduce the performance of the anaerobic digestion process [ 19 ]. The magnetic field affects the cell structure transport mechanism of Gram-negative and Gram-positive microorganisms in different ways [ 30 ].…”

Effect of Static Magnetic Field on Monascus ruber M7 Based on Transcriptome Analysis

“…Over the last few decades, numerous studies have revealed that MFs can virtually all affect living organisms, ranging from bacteria to human beings, [ 9 , 50 , 51 , 52 , 53 ]. However, the underlying mechanisms are still unclear [ 54 , 55 ], especially the impact of SMF on filamentous fungi. Therefore, we explored the effect of SMF on M. ruber M7 and its related molecular mechanisms.…”

Exploring the effect of attractive and repulsive magnetic field on electricity generation and microbial community in microbial fuel cells

“…38,39 Li et al 18 found that adding 100-mT MF promoted the maximum voltage of Shewanella-inoculated MFCs that might be because of the oxidative stress mechanism to enhance bioelectrochemical activity. Geng et al 40 studied the effects of an external MF with 70 mT MF on microbial metabolism. The results showed that MF could change the abundance of functional genes, which contents of environmental information processing, cellular processes, genetic information processing, human diseases, and organismal systems.…”