Bacteria are useful model organisms, allowing the study of many aspects of biological function, as well as enabling the genetic modification and changing of protein expression.
The relative simplicity of bacterial genomes, with the lack of introns and most being haploid, allows understanding of protein expression.
Recombineering systems, including lambda red, are able to knock-out specific genes. Crispr can be used to replace specific sections of gDNA, or to remove specific genes.
The simplicity, and lack of membranes, allows for easy access to bacterial gDNA, as well as the ability to transform plasmids by horizontal gene transfer mechanisms.