Characterization and Genome Insights of Two Novel Plastic-Degrading Acinetobacter Species

Abstract

The ubiquitous presence of Acinetobacter species in the environment holds significant biotechnology potential, particularly in the degradation of various pollutants. In this study, we present two plastic-degrading bacteria, strains CAAS 2-6T and CAAS 2-13T, isolated from landfill leachate and a strawberry farmland, respectively. Strain CAAS 2-6T showed the highest 16S rRNA sequence similarity (97.7%) with Acinetobacter gerneri DSM 14967T, while strain CAAS 2-13T was most closely related (99.6%) to Acinetobacter gerneri PS-1T. Phylogenetic analysis of 16S rRNA and gyrB-rpoB genes placed both strains on distinct branches. Genomic comparisons revealed the highest digital DNA-DNA hybridization (dDDH) / average nucleotide identity (ANI) values for CAAS 2-6T with Acinetobacter indicus CIP 110367T (22.7%/77.0%) and for CAAS 2-13T with Acinetobacter gerneri PS-1T (66.5%/96.0%). Based on phenotypic and chemotaxonomic data, we propose strain CAAS 2-6T as the novel species Acinetobacter lentus sp. nov. (type strain CAAS 2-6T = GDMCC 1.3951T = JCM 36321T = KCTC 8156T), and strain CAAS 2-13T as the novel subspecies Acinetobacter kanungonis subsp. fragariae subsp. nov. (type strain CAAS 2-13T = GDMCC 1.3956T = JCM 36322T = KCTC 8157T). Both strains utilized PLA, PBSA, PBS, PBAT, and PBT as sole carbon sources, with CAAS 2-6T exhibiting superior growth on PBSA, PBS, and PBAT. Genomic annotation identified genes encoding plastic-degrading enzymes multicopper oxidase AbMCO and alkane hydroxylase AlkB. Enzymatic depolymerization assays confirmed in vitro production of plastic monomers. These findings expand the known metabolic capabilities of Acinetobacter and provide promising new candidates for plastic bioremediation. IMPORTANCEAcinetobacter spp. demonstrate significant potential for plastic bioremediation. We characterize two novel strains: CAAS 2-6T (A. lentus sp. nov.) and CAAS 2-13T (A. kanungonis subsp. fragariae subsp. nov.), capable of degrading five major polyesters (PLA, PBAT, PBT, PBS, PBSA) as sole carbon sources. Genomic and enzymatic analyses identified multicopper oxidase (AbMCO) and alkane hydroxylase (AlkB) as key depolymerase. This work: (i) Expands plastic-degrading Acinetobacter diversity; (ii) Provides novel biocatalysts and genomic resources; (iii) Delivers engineerable microbial chassis.