BIOREACTOR & ITS

APPLICATION

S

BIOREACTOR A bioreactor  is a vessel in which a chemical process is carried out which involves organisms or biochemically active substances derived from such organisms.

Aerobic bioreactor: Need adequate mixing and aeration.

Anaerobic bioreactor: no need for sparging or agitation.

The function of the bioreactor is to provide a suitable environment in which an organism can efficiently produce a target product—the target product might be

Cell biomassMetaboliteTranformed Product

 The performance of any bioreactor depends on the following key factors:

Agitation rate Oxygen transfer Temperature Foam production

pH

BIOREACTOR SHOULD HAVE FOLLOWING QUALITIES

The vessel – capable of being operated aseptically for a number of days.

Adequate aeration and agitation – meet requirements of micro-organisms.

Power consumption should be as low as possible.

Temperature control and pH should be provided.

Sampling facilities should be provided.

Evaporation losses from fermenter should not be excessive.

Minimal use of labor in operation, harvesting, cleaning and maintenance.

Should have internal smooth surfaces .

Containment involves prevention of escape of viable cells from a fermenter or downstream equipment.

Aseptic operation involves protection against contamination.

BIOREACTOR DESIGN

VESSEL:

In fermentation with strict aseptic requirements it is important to select materials that can withstand repeated steam sterilization cycles. Two basic types of fermenters are used.• On small scale it is possible to use glass

and/or stainless steel.1. Glass vessel with a round or flat bottom

and a top flanged carrying plate.• The large glass containers originally used

were borosilicate battery jars.• They are sterilized by autoclaving.• Largest possible diameter-60cm.

VESSEL:• Glass is useful because it gives smooth

surfaces, is nontoxic, corrosion proof and it is easy to examine the interior of the vessel

• A glass cylinder with stainless-steel top and bottom

plates• Vessels with two stainless steel plates are also

used • More expensive.• Sterilized in situ.• Pilot-scale and industrial scale – stainless steel

VESSEL:

•Aseptic seal – made between glass and glass, glass and metal or metal and metal joints between bioreactor vessel and a detachable top or base plate.

GLASS AND STAINLESS STEEL FERMENTERS

TEMPERATURE CONTROL•Adequate provision for temperature control effect design of vessel body.•Heat is produced by microbial activity and mechanical agitation. If this heat is not ideal for particular manufacturing process then it may be added to or removed from the system.•Provision of heat – by placing the fermenter in thermostatically controlled bath or by use of internal heating coils or by a silicone heating jacket through which water is circulated•Silicone jacket consists of double silicone rubber mats wrapped around the vessel with heating wires between the two mats.•Cooling surface/cooling water. With increase in size of fermenter, silicone jackets are inadequate to remove heat produced by fermentation process so internal coils are used and cold water is circulated to achieve correct temperature.

Aeration

Aeration provide microorganisms in submerged culture with sufficient oxygen for metabolic requirements.

Agitation It is mixing or uniform suspension of microbial cells in homogeneous nutrient medium.

Mechanical agitation is required in fungal and actinomycete fermentations.

Structural components involved in aeration and

agitationAgitator (impeller)

Baffles

Aeration system (sparger)

Agitator (impeller)

Achieve mixing objectives – bulk fluid and gas-phase mixing, air dispersion, oxygen transfer, heat transfer, suspension of solid particles and maintaining uniform environment throughout vessel contents.

Impellers

Baffles

Baffles incorporated into agitated vessels of all sizes to prevent vortex and to improve aeration efficiency.

Metal strips roughly one-tenth of vessel diameter and attached radially to the wall.

Usually, four baffles are used, but larger bioreactor may have 6 or 8 baffles.

Minimizes microbial growth on bioreactor walls.

Extra cooling coils may be attached to baffles to improve cooling.

Baffle

BAFFLES IN FERMENTER

AERATION SYSTEM (SPARGER)• A sparger is defined as a device for introducing air into liquid of fermenter • Three basic types – porous sparger- Orifice sparger – a perforated pipe- Nozzle sparger – an open or partially closed pipe- Combined sparger-agitator may be used in laboratory fermenters.

Feeding ports

Addition of inoculum, nutrients and other supplements.

Sampling ports to test.

Additions of acid/alkali – silicone tubes pumped by peristaltic pumps after aseptic connection.

In larger bioreactor nutrition reservoirs and associated piping- integral parts – can be sterilized with vessel.

Foam controlFoam is produced during most microbial fermentations.

Foaming may occur either due to a medium component, e.g., protein present in the medium, or due to some compound produced by the microorganism. Proteins are present in corn-steep liquor, pharma media, peanut meal, soybean meal, etc.

Minimize foaming.

Excessive foaming – danger that filters become wet resulting in contamination.

Siphoning – loss of all or part of contents of bioreactor.

APPLICATIONS OF

BIOREACTOR

APPLICATIONS

A bioreactor may also refer to a device or system meant to grow cells or tissues in the context of cell culture.

These devices are being developed for use in tissue engineering 

The bioreactor is modular in nature and carry out all the processes of fermentation in a single contained environment.

Bioreactor plays a core role in bioprocess.

Stirred tank bioreactors are commonly used in fermentation industry.

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Due to simple technology and higher yield solid state bioreactors are widely used in industries.

Ethanol fermentation is done by saccharomyces cerevisiae in bioreactor.

Organic acids e.g. acetic acid and butyric acid are formed in bioreactor by the Eubacterium limosum.

Thienamycine an antibiotic also produced in bioreactor.

Glucomylase is produced by Auerobasidium pullulans in bioreactor .