The researchers then snipped small pieces off the mushroom's gill tissue and added it to a flask containing the altered bacterium.
Over the course of several days, as the bacterium goes through its lifecycle, it transfers a portion of its plasmid out of its cell right into the mushroom cell, and integrates the introduced gene into the chromosome of the mushroom.
Next, the researchers exposed the mushroom cells to hygromycin. The antibiotic kills all the normal cells, separating out those that have been genetically altered for resistance.
The test demonstrates that if a second gene, insulin for example, were to be patched in the plasmid, that gene would be expressed as well.
"There is a high probability that if the mushroom cell has the hygromycin resistance gene, it will also have the partner gene," Dr. Romaine added.
The degree of gene expression ultimately depends on where exactly the imported gene lands in the mushroom chromosome, among a complexity of other factors, but researchers point out that the process of producing biopharmaceuticals is potentially faster and cheaper with mushrooms than conventional technologies. Unlike plants that have long growth cycles, "with mushrooms, we can use commercial technology to convert the vegetative tissue from mushroom strains stored in the freezer into vegetative seed. A crop from which drugs may be extracted could be ready in weeks," Dr. Romaine said. A mushroom-based biofactory also would not require expensive infrastructure set up by major drug companies, he added.