cAMP-Mediated Biofilm eDNA Transfer Facilitates the Resilience of Soil Microbiome to Agrochemical Stress

Abstract

Soil microorganisms utilize extracellular DNA (eDNA)-based biofilms as a defense against xenobiotics. However, the specific effects and transfer pathways of eDNA under persistent agrochemical exposure remain unclear. This study examined the transfer dynamics of carbofuran-hydrolase gene pchA from Pseudomonas stutzeri PS21. During biofilm formation, pchA was released from eDNA, leading to an enrichment of beneficial microorganisms such as Acidobacteria and Elusimicrobia, which enhanced organic compound metabolism and improved soil microbiome resilience. An increase in the pchA-associated mobile genetic elements and the colocalization of pchA with other bacterial species indicated the potential horizontal gene transfer (HGT) under carbofuran exposure. Additionally, carbofuran triggered a cAMP-dependent apoptotic pathway, leading to a 59.6% increase in pchA copy number, which suggested that cAMP played a role in initiating HGT. In conclusion, the cAMP-mediated interspecific transfer of pchA could enhance microbial coadaptation to carbofuran contamination, thereby strengthening the collective defense of soil microbiome against agrochemical stress.