Mechanisms of indigenous bacteria response to copper stress in biogas slurry system

Indigenous bacteria effectively removed copper from biogas slurry. More heavy metals accumulated in LB-EPS, though bacteria secreted more TB-EPS than LB-EPS. The primary removal pathway for copper involved their mineralized precipitation in the cell wall and binding to functional groups in various cellular components. Heavy metal stress significantly altered both the species structure and functional gene composition of the indigenous bacterial community. The indigenous bacterial community upregulated genes related to heavy metal homeostasis, efflux, and DNA repair, enhancing its resistance to high concentrations of copper