Microbiome-Soil Interactions Drive the Biodegradation of a Dialdehyde Cellulose-Based Superabsorbent Polymer

The rising interest in eco-friendly technological solutions for agroecosystems has stimulated the development of biodegradable polymeric hydrogels as alternatives to commercially available synthetic materials. In this work, the biodegradation behavior of two polymer-type materials was assessed under soil-burial conditions: a hybrid biobased material (DAC-BioSAP) composed of dialdehyde cellulose (DAC), itaconic acid, and acrylic acid, and a commercial potassium polyacrylate superabsorbent (C-SAP). Their effects on soil microbial structure, taxonomic composition, and relative abundance were examined using metagenomic analysis and compared with the unamended soil (CK). Soil enzyme activities, CO2 emission kinetics, weight-loss monitoring, and complementary physicochemical analyses of both materials were also conducted. DAC-BioSAP exhibited significant biodegradation, losing ∼26% of its initial weight after 160 days. Metagenomic profiling of bacterial 16S sequences revealed that DAC-BioSAP promoted a more balanced microbial community, marked by increased abundances of Chloreflexi, Gemmatimonadota, and Acidobacteriota, and was associated with higher CO2 release compared to C-SAP and CK. In contrast, statistical analysis revealed that DAC-BioSAP-amended soils exhibited a pronounced decline in Firmicutes and related taxa compared to CK. These findings demonstrate that the incorporation of DAC and itaconic acid into BioSAP materials induces faster decomposition in the soil than commercial synthetic SAP and that bacterial communities primarily mediate its biodegradation.