With the advent of biotechnology, one of the pioneering biotech companies, Genentech, in 1981 succeeded in cloning and patenting the gene for BST. Monsanto had been working along the same lines and struck a deal with Genentech in 1979 to license Genentech's patents and collaborate on development of a recombinant version of BST – a process on which Monsanto would invest $300 million. The two companies used genetic engineering to clone the BST gene into "E. coli". The bacteria are grown in bioreactors, then broken up and separated from the rBST, which is purified to produce the injectable hormone. They published their first field trial results in 1981.