Convergence of soil bacterial communities with time and reduction of bacterial interaction complexity in response to meso- and microplastic stress

The ecological consequences of meso-and microplastics (MMPs) on soil health are far from being understood, especially lacking information on how MMPs perturbations affect soil bacterial succession patterns. This work investigated how mulching film-derived MMPs existence affected soil properties and bacterial characteristics, and if such changes were reflected in the architecture of biotic networks. The obtained results suggested that MMPs exerted potential changes in soil nutrients and enzymatic activities, and the extent of such response was strongly related to MMPs characteristics and exposure time. The abundance of the top ten phyla in MMPs-treated soil significantly varied with the incubation time before Day 45, but gradually converged over the following 45 days. Besides, the existence of MMPs increased biotic network complexity in the short run but reduced the complexity with the prolonging of time. MMPs significantly altered the network structure of soil microbial communities at the keystone species level, and the number of the keystone taxa shaping network showed a descent tendency over time. According to Partial Least Square Structural Equation Model (PLS-SEM) analysis, MMPs pollution could significantly and directly affect soil nutrients, further changing soil microbial characteristics. Additionally, soil microbes were also indirectly regulated by soil enzymatic activities in MMPs-polluted soil. This work could provide insights into the potential ecological effects of mulching film residues in soil environments.