Table 1.

Summary of the biological effects of antifoam addition to bioprocesses.

Organism	Vessel	Antifoam composition	Effect on recombinant protein yield	Effect on growth rate of cells	Other observations/ mechanisms	References
		S184 (Liquid single component: silicone oil)	Reduces specific activity (mUg-1 dry cell mass)	No change below 250 ppm. No data reported above 250 ppm	OTR reduced in early stages of cultivation	[19]
Eschericia coli K-12 producing β-galactosidase fusion protein	Bioreactor (2 L and 60 L working volume)	SLM54474 (Liquid single component; polypropylene glycol	Reduces specific activity	Decreases with increasing concentration	Minimal effect on OTR and kLa	[19]
		VP1133 (Liquid single component; silicone oil/polypropylene glycol mixture)	Increases volumetric activity (mU)	No change below 250 ppm. No data reported above 250 ppm	OTR reduced in early stages of cultivation	[19]
		SE9 (Aqueous emulsion of S184 silicone oil)	Increases volumetric activity (mU)	Low µ at 555 ppm. High µ at 5000 ppm	OTR reduced in early stages of cultivation	[19]
Geobacillus thermoleovorans secreting α-amylase	Shake flasks	PEG8000 (Liquid single component; polyethylene glycol)	Increases α-amylase titre (UmL-1 culture medium) at 0.5%	No effect	Increased membrane permeability hypothesized	[34]
Bacillus subtillis secreting α-amylase	Bioreactor	PEG600 (Liquid single component; polyethylene glycol)	Increases productivity (U mL-1 h-1) by a factor of 1.5 at 20%	Not reported	Cells become “more hydrophilic” as measured by aqueous two-phase partition	[33]
Bacillus amyloliquefaciens secreting α-amylase	Bioreactor	PEG600 (Liquid single component; polyethylene glycol)	Reduces productivity by a factor of 2 at 20%	Not reported	Cells become “more hydrophobic” as measured by aqueous two-phase partition	[33]
Schizosaccharomyces pombe secreting human transferrin	Not clearly defined; probably shake flasks	PEG8000 (Liquid single component; polyethylene glycol)	Increases titre at 0.1%	Growth defect at 1%	None	[35]
Saccharomyces cerevisiae secreting Fc fusion protein	Shake flasks	Sigma Antifoam C (Aqueous emulsion; 30% emulsion of silicone polymer)	Decreased yield above 1%	No effect up to 8%	None	[10]
		Struktol SB2121 (Liquid single component; polyalkylene glycol)	Decreased yield above 1%	Decreased cell numbers with increasing concentration 0% to 8% measured by optical density	None	[10]
Pichia pastoris secreting Fc fusion protein	Shake flasks	Struktol J673A (Hydrophobic solid dispersed in carrier oil; alkoxylated fatty acid ester on a vegetable base	Decreased yield above 1%	Increasing cell numbers with increasing concentrations 0% to 8% measured by optical density	None	[10]
		Sigma Antifoam A (Aqueous emulsion; 30% emulsion of silicone polymer)	0.6% - 1% increases total yield	At 0.6% µ = 0.12 h-1 compared to control 0.13 h-1	0.6% increases secretion and retention of GFP	[32], unpublished data
		Sigma Antifoam C (Aqueous emulsion; 30% emulsion of silicone polymer)	0.6% - 1% increases total yield	At 0.8% µ = 0.09 h-1 compared to control 0.13 h-1	0.8% increases proportion of GFP secreted and doubles secretion compared to control	[32], unpublished data
Pichia pastoris secreting green fluorescent protein (GFP)	100 mL shake flask containing 20 mL culture	Struktol J673A (Hydrophobic solid dispersed in carrier oil; alkoxylated fatty acid ester on a vegetable base	0.4% to 1% increases total yield; 1% almost doubles yield	At 1% µ = 0.19 h-1 compared to control 0.13 h-1	0.8% increases proportion of GFP secreted and doubles secretion compared to control	[32], unpublished data
		Fluka P2000 (Liquid single component; polypropylene glycol)	0.6% to 1% increases total yield; 1% doubles total yield	At 1% µ = 0.15 h-1 compared to control 0.13 h-1	0.6% increases proportion of GFP retained	[32], unpublished data
		Struktol SB2121 (Liquid single component; polyalkylene glycol)	0.4% to 1% increases total yield; 1% doubles total yield	At 1% µ = 0.14 h-1 compared to control 0.13 h-1	0.6% increases proportion of GFP retained	[32], unpublished data