Back to the Future: Decomposability of a Biobased and Biodegradable Plastic in Field Soil Environments and Its Microbiome under Ambient and Future Climates

Decomposition by
microorganisms of plastics in soils is almost
unexplored despite the fact that the majority of plastics released
into the environment end up in soils. Here, we investigate the decomposition
process and microbiome of one of the most promising biobased and biodegradable
plastics, poly­(butylene succinate-co-adipate) (PBSA),
under field soil conditions under both ambient and future predicted
climates (for the time between 2070 and 2100). We show that the gravimetric
and molar mass of PBSA is already largely reduced (28–33%)
after 328 days under both climates. We provide novel information on
the PBSA microbiome encompassing the three domains of life: Archaea,
Bacteria, and Eukarya (fungi). We show that PBSA begins to decompose
after the increase in relative abundances of aquatic fungi (Tetracladium spp.) and nitrogen-fixing bacteria. The PBSA
microbiome is distinct from that of surrounding soils, suggesting
that PBSA serves as a new ecological habitat. We conclude that the
microbial decomposition process of PBSA in soil is more complex than
previously thought by involving interkingdom relationships, especially
between bacteria and fungi.