Fed-batch Culture- Definition, Principle, Process, Types, Applications, Limitations

Fed-batch culture is a semi-continuous bioprocess that involves the periodic or continuous addition of nutrients to a bioreactor, while the products are harvested only at the end of the process. It is a modification of batch culture, where all the substrates are added at the beginning of the fermentation and no nutrients are added during the process. Fed-batch culture is widely used in industrial applications because it offers several advantages over batch and continuous cultures, such as:

  • It extends the productive duration of the culture by providing fresh nutrients and avoiding substrate depletion or inhibition.
  • It can be used to switch genes on or off by changing the substrate concentration or composition, which can affect the expression of desired products.
  • It can be manipulated for maximum productivity using different feeding strategies, such as discontinuous or continuous feeding, fixed or variable volume, and feedback control.
  • It can achieve high cell densities and high product yields by limiting the growth rate and avoiding catabolite repression or Crabtree effect.
  • It can reduce the broth viscosity and water loss by evaporation by adding concentrated or gaseous substrates.
  • It can reduce the equipment footprint and operational costs by using smaller bioreactors and less medium compared to batch or fed-batch processes.

Fed-batch culture is suitable for bioprocesses that aim for high biomass density or high product yield, especially when the desired product is positively correlated with microbial growth. It is also useful for bioprocesses that involve substrate inhibition, metabolic regulation, or gene expression control. Some examples of products produced by fed-batch culture are antibiotics, enzymes, amino acids, organic acids, vaccines, and recombinant proteins.