Biochar suppression of antibiotic resistance genes in the soil microbiome

Antimicrobial resistance (AMR) can emerge in soil from trace amounts of antibiotics used in agricultural systems for disease prevention in livestock. Researchers examined how oak wood biochar, produced through pyrolysis at a high temperature of 7600°C, affects the soil microbiome in a parkland soil environment, both with and without the antibiotic sulphamethazine (SMZ).

Using stable isotope probing combined with metagenomics, the study identified active microorganisms and measured the prevalence of antimicrobial resistance genes (ARGs). The findings showed that oak biochar significantly reduced ARG prevalence in the active heavy water metagenome by 58% compared to control soils, dropping from 23,485 ARGs to 10,002 ARGs.

The antibiotic SMZ alone increased ARG prevalence to 26,193 ARGs in the metagenome. However, when biochar and SMZ were used together, ARG prevalence was lowest at 16,890 ARGs, lower than both the control and SMZ-only treatment groups. This reduction in ARGs is likely due to a combination of ARG adsorption, antibiotic immobilization, and changes in the microbial community structure.

The study suggests that biochar could be a valuable soil amendment for reducing the spread of AMR in agricultural environments.