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Physical, Chemical and Biological Characterization of Six Biochars Produced for the Remediation of Contaminated Sites
Published on: November 28, 2014
Magnetic biochar promotes the risk of mobile genetic elements propagation in sludge anaerobic digestion
Yanru Zhang1, Yinping Xiang2, Rui Xu3
1Hunan Academy of Forestry and State Key Laboratory of Utilization of Woody Oil Resource, Changsha, 410004, China; School of Chemical Engineering, Zhengzhou University, Zhengzhou, 450001, China; College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China.
Abstract:
Mobile genetic elements (MGEs) mediated horizontal gene transfer is the primary reason for the propagation of antibiotic resistance genes in environment. The behavior of MGEs under magnetic biochar pressure in sludge anaerobic digestion (AD) is still unknown. This study evaluated the effects of different dosage magnetic biochar on the MGEs in AD reactors. The results showed that the biogas yield was highest (106.68 ± 1.16 mL g-1 VSadded) with adding optimal dosage of magnetic biochar (25 mg g-1 TSadded), due to it increased the microorganism's abundance involved in hydrolysis and methanogenesis. While, the total absolute abundance of MGEs in the reactors with magnetic biochar addition increased by 11.58%-77.37% compared with the blank reactor. When the dosage of magnetic biochar was 12.5 mg g-1 TSadded, the relative abundance of most MGEs was the highest. The enrichment effect on ISCR1 was the most significant, and the enrichment rate reached 158.90-214.16%. Only the intI1 abundance was reduced and the removal rates yield 14.38-40.00%, which was inversely proportional to the dosage of magnetic biochar. Co-occurrence network explored that Proteobacteria (35.64%), Firmicutes (19.80%) and Actinobacteriota (15.84%) were the main potential host of MGEs. Magnetic biochar changed MGEs abundance by affecting the potential MGEs-host community structure and abundance. Redundancy analysis and variation partitioning analysis showed that the combined effect of polysaccharides, protein and sCOD exhibited the greatest contribution (accounted for 34.08%) on MGEs variation. These findings demonstrated that magnetic biochar increases the risk of MGEs proliferation in AD system.
Insights
Magnetic biochar addition to anaerobic digestion (AD) sludge increases mobile genetic elements (MGEs) abundance, raising antibiotic resistance gene risks. However, optimal magnetic biochar dosage boosts biogas yield by enhancing microbial activity.
Area of Science:
- Environmental microbiology
- Biotechnology
- Biochar applications
Background:
- Mobile genetic elements (MGEs) drive antibiotic resistance gene spread via horizontal gene transfer.
- The impact of magnetic biochar on MGEs in anaerobic digestion (AD) sludge is not well understood.
- Investigating MGEs behavior under magnetic biochar influence is crucial for managing AD systems.
Purpose of the Study:
- To evaluate the effects of varying magnetic biochar dosages on MGEs in AD reactors.
- To assess the influence of magnetic biochar on microbial communities and biogas production.
- To determine the relationship between magnetic biochar, MGEs, and potential host bacteria.
Main Methods:
- Anaerobic digestion experiments with different magnetic biochar dosages.
- Quantification of MGEs absolute and relative abundance using molecular techniques.
- Analysis of microbial community structure and co-occurrence networks.
- Redundancy analysis and variation partitioning to identify influencing factors.
Main Results:
- Optimal magnetic biochar dosage (25 mg g⁻¹ TSadded) maximized biogas yield by enhancing hydrolysis and methanogenesis.
- Magnetic biochar significantly increased total MGEs abundance (11.58%-77.37%) and specifically enriched ISCR1 (158.90-214.16%).
- IntI1 abundance decreased, with removal rates of 14.38-40.00%, inversely proportional to biochar dosage.
- Proteobacteria, Firmicutes, and Actinobacteriota were identified as main MGEs hosts.
- Polysaccharides, protein, and soluble chemical oxygen demand (sCOD) were key drivers of MGEs variation.
Conclusions:
- Magnetic biochar alters MGEs abundance by modifying host community structure and abundance in AD systems.
- While enhancing biogas production, magnetic biochar application increases the proliferation risk of MGEs.
- Further research is needed to balance biogas optimization with the control of antibiotic resistance gene reservoirs.
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