BATCH CULTURE

Ganesh Kumar Padmanabhan

Rohit Rajendran

Subramaniam Iswar

Pravin Babu Sivanandam Thangaraj

Raul Tejeida Olvera

Ming Jin

Introduction:

Batch processes operate in closed systems; substrate is added at the beginning of the process and products removed only at the end.If there are no leaks or evaporation from the vessel, the liquid volume in batch reactors can be considered constant.Most commercial bioreactors are mixed vessels operated in batch.The classic mixed reactor is the stirred tank; however mixed reactors can also be of bubble column, airlift or other configuration.

Operation:

Batch cultivation

MASS IN THROUGH THE SYSTEM BOUNDARIES

MASS OUT THROUGH THE SYSTEM BOUNDARIES

MASS GENERATED WITHIN THE SYSTEM

MASS CONSUMED WITHIN THE SYSTEM

S0 , X0, P0St , Xt PtVr

MASS ACCUMULATED WITHIN THE SYSTEM

+ - =

-

VR = culture volume

Ci = moles i

unit culture volume

rfi =moles I formed by the reaction

unit culture volume unit time

d

dt

VR ci

= VR + rfi

Important equations for a batch process:

Advantages

Simplicity of use.Operability and reliability.Production of secondary metabolites that are not growth-related (i.e., produced when the organism enters stationary phase);Fewer possibilities of contamination: all of the materials required for the bioprocess are present in the vessel and sterilized before the run starts. The only material added (with the exception of the inoculum at the beginning of the bioprocess) and removed during the course of a batch fermentation are the gas exchange, and if using a bioreactor, sterile antifoam and pH control solutions if required.It is easy to assign a unique batch number to each run, generating high confidence in the history of each batch of product. This is critically important in a highly regulated environment.

Disadvantages

Culture ageing, and more importantly differentiation, can be a specific problem, especially so with growth-related products ;

Build up of toxic metabolites can restrict cell growth and product formation;

Initial substrate concentrations may have to be limited due to problems with inhibition and repression effects, therefore affecting the amount of product that can be obtained from such simple systems;

The use of batch cultures in industrial systems can lead to an increased nonproductive period due to down time required for cleaning, re-sterilization, filling and cooling of equipment;

Cellular autolysis may occur during the decline and stationary phase, affecting the amount of product, its composition and potentially adding to downstream processing challenges due to release of autolytic breakdown products, activation of proteases.

Practical Fermentation Technology Edited by Brian McNeil and Linda M. Harvey2008 John Wiley & Sons, Ltd. ISBN: 978-0-470-01434-9

Xanthan gum Production

Time (hrs)

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