Extreme temperature change could ruin the final products. I'd flood the bioreactor with inert gas. Nitrogen ought to do it and we got plenty of it. Edit: this

Extreme temperature change could ruin the final products. I'd flood the bioreactor with inert gas. Nitrogen ought to do it and we got plenty of it. Edit: this company actually advertises that: Pure nitrogen is used to control the growth rate before harvesting. https://www.concoa.com/applications/bioreactors https://www.concoa.com/applications/bioreactors