Table 1

Comparison of E. coli- and soybean-derived mSEB starting materials and yields

Expression systemaVol of starting material (liters)bStarting biomasscTotal soluble protein from biomassdRecoverable yield of vaccine (g)e
E. coli cell culture56.5 (from fermentor)2,543 g of bacterial cell pellet28.127 g8.297
Transgenic soybean seeds1.0 (soy powder)800 g of soy powder per liter320.000 g of protein per liter (theoretical)12.800 (theoretical)
  • a E. coli-derived mutant SEB (L45R/Y89A/Y94A) was produced as described previously (6). Soy-mSEB was produced as described in Materials and Methods.

  • b The volume of E. coli cell culture was taken from a previous report (41). One liter of soy powder made by grinding transgenic seeds expressing soy-mSEB is used as a theoretical comparison.

  • c The starting biomass of E. coli-mSEB required medium filtration and concentration of the cell pellet. The size of the pellet mass was taken from a previous report (41). One liter of soy powder equals approximately 800 g and required no additional concentration or manipulation.

  • d The total soluble protein extracted from the E. coli cell pellet was taken from a previous report (41). Theoretically, 320 g of protein can be extracted from 800 g of soy powder, since approximately 40% of the total mass is protein (42). This number assumes minimal loss of protein during the extraction procedure.

  • e The total recoverable yield of E. coli-mSEB was taken from a previous report (41). Theoretically, for transgenic seeds expressing soy-mSEB at 4%, 320 g of total protein contains approximately 12.8 g of soy-mSEB (42). This number does not account for any losses during the purification procedures.