Enzymes and Fermentation Technology
Enzymes and Fermentation Technology tests kinetic control of biocatalysts and the design, operation, and yield of fermentation processes.
Core rules
- Enzymes lower activation energy and are not consumed. Activity depends on pH, temperature, substrate, inhibitors, and cofactors.
- Michaelis-Menten: v = Vmax[S]/(Km + [S]). Km is the substrate concentration at half Vmax; a lower Km indicates stronger apparent affinity.
- Competitive inhibition raises Km but leaves Vmax unchanged; noncompetitive inhibition lowers Vmax; uncompetitive inhibition lowers both.
- Immobilized enzymes improve reuse and stability but can introduce mass-transfer limits.
- Fermentation may be batch, fed-batch, or continuous. Sterilization, inoculum, aeration, foaming, and downstream recovery determine product quality.
- Yield is product formed per substrate consumed; productivity is product per volume per time.
Worked example
Glucose fermentation to ethanol follows C6H12O6 -> 2 C2H5OH + 2 CO2. The theoretical ethanol yield is 92 g ethanol per 180 g glucose, or 0.511 g/g. If 100 g glucose gives 40 g ethanol, the yield is 40/51.1 = 78.3% of theoretical. The gap may reflect biomass formation, evaporation, or side products; it is not automatically a kinetic failure.
Traps
Do not say Km measures reaction speed; Vmax does. Do not call a competitive inhibitor irreversible. Do not assume anaerobic fermentation is always faster than aerobic growth. Do not ignore sterilization of the fermenter and air supply. Do not report yield without specifying the basis.