Antifoams: the overlooked additive?

It is well known that foaming can become a major problem during large-scale recombinant protein bioprocesses; the vigorous stirring and introduction of gases to maintain the required dissolved oxygen (DO) concentration for the organism [1] in addition to the growth medium and protein products themselves [2], can result in the formation and stabilization of foams consisting of gas-filled liquid lamellas. Both unstable high liquid content foams and stable dry polyhedric foams may be present in a bioprocess [3] and readily accumulate. Unchecked build up of foams may result in foam escaping from the vessel, loss of sterility [4] and material, while bursting bubbles may damage proteins and cells [5] in addition to the blockage of exit filters which can pressurize the vessel and damage equipment.