The BC production increased immediately in response to the addition of 1% and 2% SSGO to the media, showing that the activity of the bacterial cells was positively affected by the presence of SSGO in the media. The dissolution of SSGO in the media increased its viscosity, which enhanced the cell activity and oxygen uptake as reported previously (Ishida, Sugano, Nakai, & Shoda, 2002). However, further increases in SSGO (4%) increased the viscosity to a very high level. This highly viscous medium might retard the growth, movement, and activity of bacterial cells. This speculation is well supported by the very low BC3 production that was observed until the fifth day and followed