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Plastic polymers are widely used in agriculture, industry, and our daily life because of their convenient and economic properties. However, pollution caused by plastic polymers, especially polyethylene (PE), affects both animal and human health when they aggregate in the environment, as they are not easily degraded under natural conditions. In this study, Enterobacter sp. D1 was isolated from the guts of wax moth (Galleria mellonella). Microbial colonies formed around a PE film after 14 days of cultivation with D1. Roughness, depressions, and cracks were detected on the surface of the PE film by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Fourier transform infrared spectroscopy (FTIR) showed the presence of carbonyl functional groups and ether groups on the PE film that was treated with D1. Liquid chromatography-tandem mass spectrometry (LC-MS) also revealed that the contents of certain alcohols, esters, and acids were increased as a result of the D1 treatment, indicating that oxidation reaction occurred on the surface of the PE film treated with D1 bacteria. These observations confirmed that D1 bacteria has an ability to degrade PE.

The activated sludge process is an essential process for treating domestic and industrial wastewaters in most wastewater treatment plants (WWTPs). This process consists of a mixture of general and special microorganisms in a form of a complex enrichment population. Thus, the exploration of activated sludge microbial communities is crucial to improve the performance of activated sludge process. In this study, we investigated the phylogenetic diversity and metabolic potential of activated sludge microbial communities in full-scale WWTPs. Four 16S rRNA gene clone libraries were constructed from activated sludge samples. In all samples, Proteobacteria was the most abundant phylogenetic group, followed by Bacteroidetes and Firmicutes. The dominance of Proteobacteria was further demonstrated by denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP). Some specific genera, e.g., Nitrosomonas, Thauera, and Dechloromonas, which significantly correlate with the functions and performance of wastewater treatment, were abundant in all samples. A large number of unclassified sequences were found in the library, suggesting that a wide variety of novel species may inhabit complex activated sludge communities. The structures of the bacterial community did not differ significantly among samples. All samples utilized the vast majority of 31 carbon sources of an EcoPlate (Biolog), suggesting that activated sludge microbial communities possess high metabolic potential and equivalent functions required for wastewater treatment.