Polysaccharide hydrogel integrated microbial consortia for reducing relative abundance of antibiotic resistance genes in soil: physical adsorption and biological regulation.

The occurrence of antibiotics and antibiotic resistance genes (ARGs) in soil ecosystems poses a significant risk to human health. However, the techniques for removing ARGs in soil remain limited. Here we developed a natural polysaccharide hydrogel (low-acyl gellan gum/chitosan, GGC) to immobilize the microbial consortia for mitigating the propagation of ARGs. The introduction of microbial consortia in GGC demonstrated high degradation efficiencies of antibiotics, which attributed to the activation of the metabolic pathway network through microbial consortia, further reducing selective pressure. Compared with the control group, the relative abundance of dominant indigenous ARGs (adeF, qacG, OXA) in soil decreased by 85.0%, 93.9% and 99.7%, respectively, due to the degradation of antibiotics, electrostatic adsorption and biological regulation by GGC + consortia. GGC + consortia also reduced the abundance of mobile genetic element (MGEs) in soil, mitigating the ARGs spread. The recyclability of GGC avoids the release of antibiotic-resistant bacteria and ARGs and achieves the removal from the soil. This study emphasizes the application value of immobilized GGC + microbial co-cultivation system in ARGs reduction, and proposes a preliminary strategy for low-carbon soil bioremediation.