In a series of experiments in the late 1960s and early 1970s, Stanley Cohen, Herbert Boyer, and their colleagues developed the techniques necessary to recombine genes in bacterial plasmids, allowing for their mass production and launching recombinant biotechnology as we know it.
In 1973, the Cohen-Boyer team introduced a plasmid fragment from one strain of Escherichia coli, conferring kanamycin resistance into another E. coli plasmid for tetracycline resistance, and then inserted the recombined DNA into live E. coli cells, which showed both characteristics.
The bacteria not only mass-produced these "molecular chimeras," but they also transcribed the gene, demonstrating the feasibility of "growing" products of research, pharmaceutical, or industrial value. US patent 4,237,224, was issued December 2, 1980. On page 51 of Cohen's laboratory notebook is his "Outline for Recombination Paper," for their 1973 publication. At the bottom, note the reminder to mention the general applicability of the method.