Screening for Putative Essential Genes in Brucella abortus Strains A19 and S2308 Using Transposon Mutagenesis

Brucella is a zoonotic pathogen that causes substantial economic losses in the livestock industry. However, the categorization of functional genes in Brucella requires further refinement. This knowledge gap was addressed by classifying gene essentiality through constructing a transposon mutant library. Mariner transposon mutant libraries were independently constructed for Brucella abortus A19 and S2308. Transposon sequencing was used to visualize the insertion sites within the mutant library, which revealed a uniform transposon distribution in both genomes and high library saturation. Furthermore, 451 and 393 putative essential genes were identified for B. abortus A19 and S2308, respectively. The functional enrichment analysis of these genes revealed that cofactor biosynthesis was the most highly represented, followed by ribosomal biogenesis, carbon metabolism, amino acid biosynthesis, and oxidative phosphorylation. Many of these genes encode known antimicrobial drug targets. This study provides a foundational resource for Brucella research, and the mutant library serves as a tool for screening functional Brucella genes.