Biofilm-associated transformation of polylactic acid (PLA) microbeads by single- and dual-species bacterial...

Biofilm formation represents a pivotal step in bioplastic biodegradation, yet the degradation is often limited by insufficient microbial colonization and unstable biofilm formation. This study investigated the early-stage biodegradation of polylactic acid (PLA) microbeads in presence of single- (Pseudomonas putida, Escherichia coli) and dual-species biofilms on after 1 and 7 days of incubation in M9 minimal medium at 30°C. PLA surface alterations confirmed that the dual-species biofilms caused interfacial transformation, as shown by the CO bond cleavage, C-O and C-C bond formation, as well as reduced thermal stability of PLA, with CO atomic ratio decreasing from 26.1 ± 0.50% to 16.0 ± 1.11% after 7 days. In multi-well plates, dual-species biofilms show higher biomass than single-species, but biofilm formation on PLA microbeads was lower than single-species P. putida. Quantification of the key intermediate metabolites lactate and pyruvate levels in dual-species biofilms show metabolic cooperation between the two species. The improved degradation performance was attributed to enhanced interfacial colonization and complementary metabolic activity that collectively promoted sustained polymer hydrolysis. These findings suggest a controllable biofilm-based strategy for improving PLA bioconversion efficiency and offer insights into designing microbial consortia for polymer biodegradation processes.