Functional heterogeneity among four co-occurring landfill bacteria during low-density polyethylene transformation

Abstract Low-density polyethylene (LDPE) transformation is usually reported for individual isolates, whereas direct comparisons among co-occurring bacteria from the same contaminated habitat are scarce. Four Gram-negative bacteria were isolated from a plastic-contaminated municipal dumpsite in Ghaziabad, India, and identified by 16S rRNA gene sequencing as Pseudomonas sp. DW, Dyella japonica DP, Enterobacter sp. DLY and Pantoea agglomerans DY. Growth, extracellular enzyme profiles, gravimetric loss, microscopy, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were compared over 45 days under a common framework. All isolates grew best at 30°C and pH 7.0. Pseudomonas sp. DW showed the highest apparent mass loss (16.07 ± 0.18%), carbonyl index (0.2444) and hydroxyl index (0.1773), the most extensive biofilm, and the only lipase/esterase activity under nutrient limitation. Enterobacter sp. DLY lost 13.96 ± 0.14% of mass and had a carbonyl index of 0.2031 without detectable lipase/esterase activity. To our knowledge, D. japonica DP and P. agglomerans DY are the first isolates of these species characterised for LDPE transformation at species level; only genus-level reports exist for Dyella and Pantoea , and Pseudomonas and Enterobacter are established LDPE-associated genera, so no taxonomic novelty is claimed for them. The principal novelty is the within-site comparison showing that similar endpoints can arise from different trait combinations, which guides strain selection for mechanistic and consortium studies.