Metabolic pathway analysis of an Acinetobacter strain capable of assimilating diverse hydrocarbons

The growing demand for sustainable bioproduction requires the development of robust microbial chassis with broad metabolic versatility and suitability for industrial applications. Acinetobacter sp. Tol 5 is a highly adhesive bacterium capable of utilizing various hydrocarbons, making it a promising chassis for immobilized whole-cell catalysis. In this study, we characterized the carbon metabolism of Tol 5 by reconstructing metabolic pathway maps from its genomic data and analyzing the transcriptomes of cells grown on ethanol, hexadecane, toluene, phenol, and L-phenylalanine. Genomic analysis revealed that Tol 5 possesses a wide range of metabolic pathways for both alkanes and aromatics, including five distinct aromatic degradation routes. Transcriptome analysis identified the specific carbon sources that regulate each degradation pathway. Most pathways were induced by their corresponding carbon sources with high specificity, whereas some were upregulated by multiple related substrates. In addition, Tol 5 appears to metabolize phenylalanine via the homogentisate pathway, which differs from the phenylacetate pathway reported in Acinetobacter baumannii. Genes involved in oxidative and osmotic stress resistance were also coordinately upregulated on hydrocarbon sources, indicating adaptation to these cellular stresses associated with carbon sources. These results provide a comprehensive view of the carbon metabolism of Tol 5 and highlight its potential as a robust microbial chassis for converting non-sugar feedstocks into valuable bioproducts, while revealing new aspects of metabolic versatility in the genus Acinetobacter. IMPORTANCEMembers of the genus Acinetobacter are ubiquitous environmental bacteria, which have attracted increasing attention in ecological and biotechnological fields due to their broad metabolic versatility and strong tolerance to environmental stress. We characterized the carbon metabolism of the hydrocarbon-degrading strain Tol 5 and identified five aromatic degradation pathways, including a toluene dioxygenase pathway and a homogentisate pathway, which are rarely reported in this genus. These findings expand the known metabolic repertoire of Acinetobacter and reveal that Tol 5 possesses aromatic degradation capabilities comparable to those of Pseudomonas putida strains, which are widely used as chassis for aromatic compound bioconversions. Furthermore, since aromatic compound metabolism has been reported to be associated with virulence and antibiotic resistance in pathogenic Acinetobacter strains, these insights may contribute to future strategies for pathogen control as well as leading the rational design of microbial chassis for sustainable bioproduction.