Biodegradation of vulcanized natural rubber by enriched bacterial consortia

The disposal of discarded vulcanized natural rubber waste has presented substantial environmental challenges. This study aimed to investigate the degradation of vulcanized natural rubber through the utilization of enriched bacterial consortia with NRE3 derived from the soil. The highest weight loss of 38.84 % was achieved with NRE3 after four weeks of incubation. Additionally, the crosslinking density of rubber decreased by 32.3 % and the tensile strength decreased from 69.1 to 9.5 MPa. SEM analysis revealed the presence of significant cracks and holes on the surface of vulcanized natural rubber. Moreover, FT-IR and XPS analyses demonstrated a decrease in the sulfur (S) and carbon (C) content of the rubber, while the oxygen (O) content increased. The concentration of SO42- in the medium increased from 478.37 to 840.26 mg/L, indicating the collapse of the rubber structure. The NMR and GC–MS findings indicated the presence of degradation products, specifically polyisoprene oligomers and terpenoids. Through high-throughput sequencing analyses, Acinetobacter, Chryseobacterium, Stenotrophomonas and other bacterial were discovered in NRE3. Based on the chemical structure characterizations and molecular analyses, a degradation pathway was proposed. These findings pave a way for utilizing rubber-degrading microorganisms present in soil and contribute to the establishment of a biodegradation method for disposing of vulcanized rubber waste.