Editing the <em>Serratia proteamaculans</em> Genome Using the Allelic Exchange Method

No specific ecological niche has been identified for <i>Serratia proteamaculans</i>. Different strains of the bacterium have been described as opportunistic pathogens of plants, animals, and humans, as plant symbionts, and as free-living bacteria. This makes <i>S. proteamaculans</i> and its particular strains promising models for research, particularly aimed at studying the role of various genes in interspecific interactions. Genome editing is one of the most significant approaches used to study gene function. However, as each bacterial species has its own characteristics, editing methods often need to be adapted. In this study, we adapted a conventional approach based on homologous recombination-the allelic exchange method-to edit the genome of <i>S. proteamaculans</i>, with the aim of examining the biological role of protealysin. Plasmids for recombination were created using the suicidal vector pRE118, and then an auxotrophic <i>Escherichia coli</i> ST18 strain was used to deliver these plasmids to <i>S. proteamaculans</i> through conjugation. This method is valid and can potentially be used to create knockouts, knockins, and point mutations in the <i>S. proteamaculans</i> genome, without the need to insert a selective marker into the genome. Key features • The genome editing method for <i>Serratia proteamaculans</i> does not require the insertion of selective markers into the genome. • The selection strategy allows obtaining 30%-40% of clones with the target mutation at the final stage. • The method can be adapted to introduce knockouts, knockins, and point mutations into the genomes of other bacteria.