Bioprocess technology is the application of engineering and biological principles to transform biological materials (like cells or enzymes) into useful products, such as pharmaceuticals, food, and biofuels
. It integrates biology and chemical engineering to create efficient large-scale production systems.A fed-batch culture is a biotechnological production process where one or more nutrients are added to the bioreactor during the cultivation
. Unlike a standard batch culture, the product remains in the vessel until the end of the run, allowing for higher cell densities and product yields.Continuous culture is a system where fresh medium is added continuously to the bioreactor, while an equal volume of culture (including cells and waste products) is simultaneously removed
. This maintains the microbial population in a steady-state exponential growth phase.Principle of Fermentation Technology:
The core principle involves the controlled growth of microorganisms (or animal/plant cells) in a nutrient medium to produce secondary metabolites or biomass
. It relies on providing an optimized environment—temperature, pH, aeration, and nutrient supply—to maximize the biocatalytic activity of the organisms.Basic Components of Fermentation:
Applications of Bioprocess Technology:
(i) Batch culture:
In a batch culture, a fixed volume of medium is inoculated with a microorganism in a closed system
. No additional nutrients are added after the start, and nothing is removed until the end of the process, except for air and gases.(ii) Phases of growth:
Microbial growth in a batch system follows four distinct phases
:A bioreactor is a specialized vessel or container that provides a controlled environment for the growth of biological organisms and the conversion of raw materials into specific products via biochemical reactions
.A packed tower bioreactor is a vessel filled with solid packing material (like plastic rings or ceramic beads) onto which microorganisms are immobilized
. The nutrient medium flows over the packing, and air is usually introduced from the bottom. It is commonly used for effluent treatment.A standard bioprocess vessel (Stirred Tank Bioreactor) is designed for aseptic operation and effective mass transfer
.Key Design Components:
(i) Airlift bioreactor:
These reactors use air/gas to achieve both aeration and agitation without mechanical moving parts
. They consist of a "riser" (where gas is injected) and a "downcomer" (where liquid circulates back), creating a highly efficient loop of circulation.(ii) Cyclone column bioreactor:
This reactor utilizes centrifugal forces (cyclone action) to separate gas from liquid or to enhance mixing
. The medium is often pumped tangentially into the column, creating a thin film or vortex that maximizes the surface area for oxygen transfer.Upstream processing refers to the early stages of a bioprocess, including inoculum development, media formulation, and sterilization, ending just before the actual fermentation begins in the bioreactor
.A pure culture is a laboratory culture containing only a single species or strain of microorganism, free from any contaminating organisms
. Maintaining pure cultures is vital for consistent product quality in industrial fermentation.Sterilization is the total destruction of all living organisms and spores to ensure monosepsis in the fermentation vessel
.(i) Inocula development:
The process of progressively increasing the volume of a pure culture from a master vial (stock) to a large volume sufficient to seed the main production fermenter (typically 5-10% of total volume)
.(ii) Media preparation:
Involves the precise formulation and dissolution of nutrients to support the target organism's growth and product synthesis
.Strain Improvement:
Techniques like mutagenesis (using UV or chemicals) and recombinant DNA technology are used to enhance the metabolic efficiency of the organism, making it produce more of the desired product
.Mass transfer is the movement of chemical species from a region of high concentration to a region of low concentration
. In bioprocessing, it primarily refers to the transfer of oxygen from gas bubbles into the liquid medium where cells can consume it.Aerobic microorganisms require a continuous supply of dissolved oxygen (DO) for respiration and product synthesis
. Since oxygen is poorly soluble in aqueous media, it often becomes the limiting factor in high-density cultures.kLa is the volumetric oxygen mass transfer coefficient
. It represents the efficiency of a bioreactor in transferring oxygen from gas to liquid. High kLa values indicate superior aeration performance.A control system maintains optimized conditions within the bioreactor by monitoring variables via sensors and adjusting them via actuators
.(i) Factors affecting kLa:
(ii) Computer-aided process control:
Involves using software (SCADA) to collect real-time data from sensors, perform complex calculations, and execute precise automated adjustments, ensuring high reproducibility and safety
.Product recovery is the set of operations performed after fermentation to separate the desired biological product from the culture medium, cells, and impurities
.This is the first step of downstream processing, where the biomass (cells) is separated from the fermentation broth using techniques like centrifugation or filtration
.Amylase is produced industrially primarily using Bacillus subtilis or Aspergillus oryzae via submerged fermentation
. It is used extensively in the starch, textile, and detergent industries.Downstream Processing (DSP) Steps:
Production of Ethanol:
Produced by the fermentation of sugars (molasses or starch) using the yeast Saccharomyces cerevisiae under anaerobic conditions
. The ethanol is then recovered and concentrated using fractional distillation.(i) Production of lactic acid:
Produced by Lactobacillus species through the fermentation of carbohydrates
. The pH must be controlled by adding calcium carbonate, forming calcium lactate, which is later acidified to recover pure lactic acid.(ii) Production of SCP (Single Cell Protein):
SCP refers to edible protein extracted from pure microbial cultures (algae, fungi, or bacteria)
. Organisms like Spirulina are grown on large scales, harvested, and dried to be used as high-protein supplements for humans or animals.