Bacteria do this naturally.
Genetic engineering increases the variety of DNA which is available for bacteria to transfer.
Critics of the biotechnology industry contend that once genetically modified plants and animals are released into the environment bacteria and viruses can accelerate horizontal gene transfer and pass on harmful traits. Biotech supporters say this risk is unproved and exaggerated. Ho examines the evidence. But, researchers earlier found evidence of horizontal transfer of GM genes to soil bacteria in the field where GM sugar beet was planted, and this has been reported in the scientific literature. They found that the GM construct persisted in the soil for at least two years after the plants were grown and harvested, and different parts of the GM construct may have transferred to unknown soil bacteria.