, BIOPROCESS ENGINEERING AND TECHNOLOGY
TOPIC : DOWNSTREAM PROCESSING – REMOVAL OF
BIOMASS FROM FERMENTED BROTH
INTRODUCTION
Downstream processing refers to the recovery and purification of biosynthetic
products, particularly pharmaceuticals, from natural sources such as animal or plant
tissue or fermentation broth, including the recycling of salvageable components and
the proper treatment and disposal of waste. It is an essential step in the manufacture of
pharmaceuticals such as antibiotics, hormones (e.g. insulin and humans growth
hormone), antibodies (e.g. infliximab and abciximab) and vaccines; antibodies and
enzymes used in diagnostics; industrial enzymes; and natural fragrance and flavor
compounds. Filtration is the most commonly used technique.
, REMOVAL OF BIOMASS FROM FERMENTOR
Solid-Liquid Separation :
The first step in product recovery is the separation of whole cells (cell biomass)
and other insoluble ingredients from the culture broth (Note: If the desired product is
an intracellular metabolite, it must be released from the cells before subjecting to
solid-liquid separation).Some authors use the term harvesting of microbial cells for
the separation of cells from the culture medium.
Several methods are in used for solid-liquid separation, these are:
1. Flotation
2. Flocculation
3. Filtration
4. Centrifugation
FLOTATION (FOAM SEPARATION) :
Foam separation depends on using methods, which exploit differences in surface
activity of materials. The material may be whole cells or molecular such as a protein
or colloid, which is selectively adsorbed or attached to the surface of gas bubbles
rising through a liquid, to be concentrated or separated and finally removed by
skimming
, FLOCCULATION :
In flocculation, the cells (or cell debris) form large aggregates to settle down for
easy removal. The process of flocculation depends on the nature of cells and the ionic
constituents of the medium. Addition of flocculating agents (inorganic salt, organic
polyelectrolyte, mineral hydrocolloid) is often necessary to achieve appropriate
flocculation.
FILTRATION:
Filtration is the most commonly used technique for separating the biomass
and culture filtrate. The efficiency of filtration depends on many factors— the size of
the organism, presence of other organisms, viscosity of the medium, and temperature.
Several filters such as depth filters, absolute filters, rotary drum vacuum filters and
membrane filters are in use.
Depth Filters:
They are composed of a filamentous matrix such as glass wool, asbestos or
filter paper. The particles are trapped within the matrix and the fluid passes
out.Filamentous fungi can be removed by using depth filters.
Absolute Filters:
These filters are with specific pore sizes that are smaller than the particles to
be removed. Bacteria from culture medium can be removed by absolute filters
Rotary Drum Vacuum Filters:
These filters are frequently used for separation of broth containing 10-
TOPIC : DOWNSTREAM PROCESSING – REMOVAL OF
BIOMASS FROM FERMENTED BROTH
INTRODUCTION
Downstream processing refers to the recovery and purification of biosynthetic
products, particularly pharmaceuticals, from natural sources such as animal or plant
tissue or fermentation broth, including the recycling of salvageable components and
the proper treatment and disposal of waste. It is an essential step in the manufacture of
pharmaceuticals such as antibiotics, hormones (e.g. insulin and humans growth
hormone), antibodies (e.g. infliximab and abciximab) and vaccines; antibodies and
enzymes used in diagnostics; industrial enzymes; and natural fragrance and flavor
compounds. Filtration is the most commonly used technique.
, REMOVAL OF BIOMASS FROM FERMENTOR
Solid-Liquid Separation :
The first step in product recovery is the separation of whole cells (cell biomass)
and other insoluble ingredients from the culture broth (Note: If the desired product is
an intracellular metabolite, it must be released from the cells before subjecting to
solid-liquid separation).Some authors use the term harvesting of microbial cells for
the separation of cells from the culture medium.
Several methods are in used for solid-liquid separation, these are:
1. Flotation
2. Flocculation
3. Filtration
4. Centrifugation
FLOTATION (FOAM SEPARATION) :
Foam separation depends on using methods, which exploit differences in surface
activity of materials. The material may be whole cells or molecular such as a protein
or colloid, which is selectively adsorbed or attached to the surface of gas bubbles
rising through a liquid, to be concentrated or separated and finally removed by
skimming
, FLOCCULATION :
In flocculation, the cells (or cell debris) form large aggregates to settle down for
easy removal. The process of flocculation depends on the nature of cells and the ionic
constituents of the medium. Addition of flocculating agents (inorganic salt, organic
polyelectrolyte, mineral hydrocolloid) is often necessary to achieve appropriate
flocculation.
FILTRATION:
Filtration is the most commonly used technique for separating the biomass
and culture filtrate. The efficiency of filtration depends on many factors— the size of
the organism, presence of other organisms, viscosity of the medium, and temperature.
Several filters such as depth filters, absolute filters, rotary drum vacuum filters and
membrane filters are in use.
Depth Filters:
They are composed of a filamentous matrix such as glass wool, asbestos or
filter paper. The particles are trapped within the matrix and the fluid passes
out.Filamentous fungi can be removed by using depth filters.
Absolute Filters:
These filters are with specific pore sizes that are smaller than the particles to
be removed. Bacteria from culture medium can be removed by absolute filters
Rotary Drum Vacuum Filters:
These filters are frequently used for separation of broth containing 10-
