The impact of climate and land use changes on biodegradability and plastisphere microbiota of bio-based and biodegradable plastics in agricultural soils

To address the issue of plastic pollution, biodegradable plastics have been developed as an alternative to conventional
non-biodegradable plastics. Nitrogen(N)-fixing bacteria have been shown to play a pivotal role in the
microbial degradation of biodegradable plastics. However, little is known about how N-fixing bacteria respond to
plastic degradation in agricultural practice. Therefore, this study aimed to (i) provide insights into the N-fixing
bacteria associated with biodegradable plastics during the early stage of degradation (after 60 days of exposure),
and (ii) examine the impact of agricultural practices and climate simulations on the enrichment of N-fixing
bacteria across various plastic types: poly(butylene succinate) (PBS), polybutylene adipate terephthalate (PBAT),
and polyethylene (PE) as a reference. Our findings revealed that N-fixing bacterial genera, particularly Sphingomonas,
Hymenobacter, Massilia, and Methylobacterium-Methylorubrum, outcompete other N-fixing bacteria in the
plastisphere at the early degradation stage, while they are almost absent in the initial soils. These bacterial
groups have been previously linked to plastic degradation and the production of plastic-degrading enzymes.
Moreover, our results indicate that agricultural practices and climate conditions did not significantly affect the
enrichment of N-fixing bacteria. Instead, this study explored the enrichment of these bacteria on biodegradable
plastics, particularly PBAT and PBS, under changing climate and land use conditions during the early degradation
phase. Additionally, we identified soil-associated minor N-fixing bacteria that dominate these N-poor
plastics in both conventional and organic farming systems. Identifying plastic-preferring microbial groups is
crucial for understanding the microbial plastic degradation process under the real world’s scenario.