Acinetobacter guillouiaestrain isolated from sludge capable of partially degrade polyethylene terephthalate: genomic and biochemical insights

The escalating accumulation of plastic waste in terrestrial and aquatic ecosystems profoundly threatens environmental health and biodiversity while impacting human well-being. Recently, many microorganisms capable of degrading polyethylene terephthalate (PET) have been reported, primarily sourced from terrestrial soils and marine environments. Notably, the challenge of PET pollution in aquatic environments has remained a persistent research concern. In this study, we present the isolation and characterization of Acinetobacter guillouiae strain I-MWF, obtained from a wastewater treatment plant in Makri, AJK, Pakistan, using molecular phylogenetic analysis based on genome sequencing. Results revealed that this strain exhibits the ability for PET powder degradation, as confirmed by HPLC/LCMS analysis. Furthermore, we conducted whole-genome sequencing using Illumina technology and bioinformatically explored this strain’s potential repertoire of lipase and esterase enzymes. Under optimized conditions of 23°C and pH 7 in mineral salt media with PET powder as the sole organic substrate, A. guillouiae I-MWF could degrade partially. Extracellular enzymes yielded PET depolymerization products identified as mono(2- hydroxyethyl) terephthalic acid and terephthalic acid. The sequenced genome of this strain spans 4.61 Mb with a mean G + C content of 38.2%, containing 4,178 coding genes, 71 tRNA, and six rRNA genes. Although no cutinase-like enzymes were identified, our analysis unveiled a diverse array of putative lipases and three esterases, all sharing the typical α/β hydrolase fold. Additionally, comprehensive molecular modelling analysis suggested that some of the 18 identified extracellular hydrolases may be involved in polyester enzymatic depolymerization processes.