Complete Genome Analysis of Paracandidimonas lactea PBAT-8 Reveals Candidate Functions Associated with PBAT Transformation

Abstract

Poly(butylene adipate-co-terephthalate) (PBAT) is widely used in biodegradable agricultural mulch films, yet its degradation may remain incomplete under field conditions, leading to persistent residues in soil. To investigate microbial processes potentially affecting PBAT fate, we characterized a PBAT-degrading bacterium, Paracandidimonas lactea PBAT-8, isolated from long-term plastic-mulched agricultural soil. In minimal salts medium with PBAT as the sole added carbon source, PBAT-8 caused a film mass loss of 6.6% ± 0.14% after 40 days. Hybrid PacBio HiFi and Illumina sequencing generated a complete 4,058,150 bp circular chromosome with a GC content of 61.3% and no detected plasmids. The genome contained 3658 predicted protein-coding genes and encoded functions related to membrane transport, signal transduction, energy metabolism, and the metabolism of aliphatic and aromatic compounds. Six hydrolase-related genes, including alpha/beta hydrolase- and dienelactone hydrolase-family proteins, were prioritized as candidates potentially involved in ester hydrolysis or downstream conversion of PBAT-derived intermediates. Additional genes associated with the transport and metabolism of aliphatic and aromatic compounds were also identified. Although the direct roles of these candidates require experimental validation, the degradation phenotype and complete genome of PBAT-8 provide a genomic basis for further investigation of PBAT transformation in agricultural soils.