Genomic Insights into Enterobacteriaceae: Pan-Genome Analysis, and Functional Profiling

Enterobacteriaceae is a diverse family of Gram-negative bacteria that includes clinically significant pathogens such as Enterobacter spp., Escherichia coli, Klebsiella pneumoniae, Salmonella enterica, and Shigella spp. These bacteria exhibited remarkable genomic plasticity, facilitating adaptation to various environments, acquisition of antimicrobial resistance (AMR) genes, and the evolution of virulence traits. This study conducted a comprehensive pan-genome analysis of 22 Enterobacteriaceae strains to investigate their genetic diversity, with a focus on multidrug resistance (MDR) genes and functional classification using the Clusters of Orthologous Groups (COG) database. The pan-genome analysis revealed a completely open genomic structure, with no core genes shared among all strains. Instead, the accessory genome dominated, comprising genes associated with virulence, host adaptation, and antimicrobial resistance. MDR genes were exclusively found in the accessory genome, highlighting their variable distribution and potential for horizontal transfer. Functional annotation using the COG database showed a consistent distribution of genes related to essential cellular functions, with carbohydrate and amino acid metabolism being the most represented categories. However, variations in certain functional groups indicated strain-specific adaptations and genomic plasticity. These findings underscored the evolutionary dynamics of Enterobacteriaceae, where the accessory genome drives genetic diversity and adaptation. The exclusive presence of MDR genes in the accessory genome emphasized the role of horizontal gene transfer in antimicrobial resistance dissemination. Understanding these genomic patterns is crucial for tracking the emergence of resistant strains and developing effective therapeutic and public health strategies.