Unit 5: Industrial Biotechnology

Introduction to Bioprocess Technology

Definition: Bioprocess Technology

Bioprocess technology (or bioprocessing) is the use of complete living cells (like bacteria or yeast) or their components (like enzymes) to perform a desired chemical transformation. It is the core of industrial biotechnology, used to manufacture products on a large scale.

A bioprocess has two main parts:

1. Upstream Processing (USP): All the steps *before* the main reaction (getting the "factory" ready).
2. Downstream Processing (DSP): All the steps *after* the reaction (harvesting and purifying the product).

Principles of Upstream Processing (USP)

Upstream processing involves preparing everything needed to start the bioprocess: the microbes, the media (food), and the sterile environment.

Media Preparation

• Definition: The culture medium is the nutrient-rich "food" designed to support the optimal growth of the microorganism.
• Components: A well-designed medium must contain:
  • Carbon Source: (e.g., molasses, glucose) for energy and building blocks.
  • Nitrogen Source: (e.g., ammonia, yeast extract) for making proteins and nucleic acids.
  • Minerals: (e.g., salts, trace elements) needed as cofactors for enzymes.
  • Water: The solvent for all components.
• Goal: The medium must be cheap (for large-scale use), available, and optimize product yield.

Sterilization

• Definition: The most critical step in USP. It is the complete destruction of all contaminating microorganisms.
• Why: If a single "weed" bacterium gets in, it can outgrow the desired microbe and ruin the entire expensive batch.
• Methods:
  • Moist Heat (Autoclave): The large bioprocess vessel and the liquid media inside are sterilized together using high-pressure steam (e.g., 121°C, 15 psi).
  • Filtration: Heat-sensitive components (like vitamins) are sterilized by passing them through a microfilter (0.22 µm pores) and then added to the cooled, sterile medium.

Design of Bioprocess Vessels (Bioreactors/Fermenters)

The bioreactor (or fermenter) is the large, contained, sterile vessel where the bioprocess actually happens.

Key Design Features:

• Sterile Construction: Made of stainless steel, which is easy to clean and sterilize. All connections must be sealed.
• Agitation System: An impeller (mixer) driven by a motor, to keep the microbes, nutrients, and oxygen evenly mixed.
• Aeration System: A sparger (a pipe with small holes) at the bottom to bubble sterile air (oxygen) into the vessel. This is essential for aerobic microbes.
• Temperature Control: A cooling jacket (an outer shell) where cold water circulates, as microbial growth generates a lot of heat.
• Monitoring Probes: Electronic sensors to monitor critical conditions like pH, temperature, and dissolved oxygen (DO) in real-time.

Introduction to Downstream Processing (DSP)

Definition: Downstream Processing

Downstream processing includes all the steps involved in the recovery and purification of a product from the bioreactor, converting it into a stable, finished product.

This is often the most complex and expensive part of the entire bioprocess, accounting for 50-80% of the total cost.

Key Stages:

Product Recovery (Separation)

1. Solid-Liquid Separation: Removing the microbial cells from the liquid medium.
   • Filtration: Passing the broth through a filter.
   • Centrifugation: Spinning the broth at high speed to pellet the cells.
2. Cell Disruption (if needed): If the product is intracellular (inside the cell, like human growth hormone), the cell walls must be broken open (e.g., high pressure, enzymes). If the product is extracellular (secreted into the media, like penicillin), this step is skipped.

Product Purification

This stage removes impurities (other proteins, media components) from the product.

• Chromatography: The most powerful purification technique. The mixture is passed through a column packed with a material (resin) that selectively binds to the target product or its impurities, separating them.

Final Processing:

• Formulation: Adding stabilizers, preservatives, or other substances to make the product active and give it a long shelf life.
• Packaging: Filling the final product into sterile vials, syringes, or containers.