Yes, one bacterium can indeed insert its DNA into another bacterium, and this process is known as horizontal gene transfer. One of the main mechanisms by which this occurs is called conjugation. In conjugation, a donor bacterium forms a physical connection to a recipient bacterium through a structure called a pilus. The donor then transfers a copy of its DNA, often in the form of a plasmid, directly to the recipient.
Another method of horizontal gene transfer is transduction, where bacteriophages (viruses that infect bacteria) can accidentally carry DNA from one bacterium to another during the infection process. Lastly, transformation involves the uptake of free-floating DNA from the environment and its incorporation into a bacterium's genome.
I can see significant implications for antibiotic resistance because these processes can facilitate the rapid spread of resistance genes among bacterial populations. For instance, if one bacterium acquires a resistance gene, it can pass that gene to other bacteria through conjugation or other forms of gene transfer. This can lead to the emergence of antibiotic-resistant strains, making infections harder to treat and posing serious challenges to public health. It emphasizes the need for careful antibiotic use and ongoing research into strategies to combat resistance.