Genomic features and alkane-metabolism profiles of three new Alcanivoracaceae bacteria isolates from the Eastern Mediterranean Sea

Marine ecosystems are increasingly exposed to petroleum pollutants and plastic waste, highlighting the importance of better understanding the microbial taxa that mediate hydrocarbon degradation. Here, we describe the genetic and metabolic toolbox of Alcanivoracaceae bacteria strains; Alcanivorax jadensis IL1 , a candidate new species - Alcanivorax davidoviea IL2, and Alloalcanivorax venustensis A6 , isolated from a petroleum-contaminated Eastern Mediterranean Sea marina. The three strains showed high metabolic capacities to utilize crude oil, linear and branched alkanes, but not mono- and polyaromatic hydrocarbons. Whole-genome sequencing and comparative genomic analyses highlighted both conserved and strain-specific repertoires of alkane uptake, hydroxylation, and downstream metabolic genes with variations in gene copy numbers and in the genomic organization of key hydrocarbon-metabolism genes. The IL1 and IL2 strains contained higher gene copy number of long-chain alkane monooxygenases ( almA ) and Baeyer-Villiger monooxygenases ( BVMO ), correlating with enhanced utilization of long-chain (≥C₁₆) n -alkanes. In contrast, strain A6 's genome included more copies of the alkane hydroxylation gene alkB in addition to flagella-based motility and chemotaxis genes. These features suggest potential trade-offs between metabolic specialization and environmental versatility among Alcanivoracaceae . Collectively, our findings expand the known genomic and physiological diversity within this family, underscore their central role in marine hydrocarbon bioremediation, and provide a framework for future studies linking genetic traits with ecological performance under petroleum-contaminated conditions.