In Vitro Degradation of Polyethylene Terephthalate using Pseudomonas species

Polyethylene terephthalate (PET) is a significant source of plastic pollution, having many industrial applications but being harmful to the environment and human well-being because of its persistence and crystallinity (~25%). While a few reports have described the degradation of PET using specific enzymes or laboratory-adapted microbial strains, the degradation potential of naturally occurring environmental isolates, particularly from wastewater treatment ecosystems, remains underexplored. This study focused on the isolation of non-engineered environmental strains Pseudomonas mendocina, P. stutzeri, and P. putida from vermifilter wastewater to assess their ability for PET degradation—a novel use of non-engineered environmental strains. Unlike previous studies primarily focused mainly on single strains or engineered microbial systems, this study systematically compares the PET degradation efficiency of individual isolates with defined bacterial consortia to assess whether cooperative interactions enhance degradation. In YSV/MSM media (37°C, 150 rpm, 60 days), P. stutzeri achieved 32 ± 0.005% weight loss (initial 0.022 g, triplicate biological/dupe technical), linked to high biofilm (148 × 10⁴ CFU/mL) and hydrophobicity (68%). P. stutzeri + P. mendocina consortium yielded 16.2 ± 0.002% in MSM, lower than individuals due to surface competition, contrasting with synergistic reports. FTIR showed ester cleavage (1715 → 1713 cm⁻¹ intensity drop).