Difference Between Batch and Continuous Fermentation

Key Difference – Batch vs Continuous Fermentation
 

The key difference between Batch and Continuous fermentation is that in batch fermentation, fermentation is done in batch-wise one after the other while in continuous fermentation, fermentation process never stops in between and it runs for a longer period of time with the feeding of fresh media containing nutrients and harvesting products at regular intervals.

Fermentation is the process of breaking down chemicals under anaerobic conditions by microorganisms such as bacteria, yeast, fungi, etc. In other words, fermentation is defined as the conversion of organic molecules into acids, gases, or alcohol in the absence of oxygen or electron transport chain as a result of metabolic processes of microorganisms. The use of this ability of microorganisms to make useful products in industrial scale is known as industrial fermentation. Batch and Continuous fermentation are two types of industrial fermentation processes that used to obtain money making useful products.

CONTENTS

1. Overview and Key Difference
2. What is Batch Fermentation
3. What is Continuous Fermentation
4. Similarities Between Batch and Continuous Fermentation
5. Side by Side Comparison – Batch vs Continuous Fermentation in Tabular Form
6. Summary

What is Batch Fermentation?

Batch fermentation is one type of industrial fermentation in which products are harvested at batch wise while stopping the process at the end of each batch. In batch fermentation, in the beginning, nutrients and microorganisms are added and run the process. It is a closed system and relatively a large fermenter is used. Microbial growth occurs via lag phase, log phase, and stationary phase. Once the fermentation process complete es, process is stopped and products are harvested. Before the next batch, fermenter is cleaned and the second batch is started newly.

Turnover rate is low in batch fermentation since the nutrients are added once and the environmental conditions are not close to natural. However, batch fermentation is highly applied in industries since it is more suitable for the production of secondary metabolites such as antibiotics, etc.

What is Continuous Fermentation?

Continuous fermentation is another type of industrial fermentation process in which fermentation is carried out for a longer period of time while adding nutrients at the beginning and in between the process and harvesting at regular intervals. Continuous fermentation performs in a small fermentor and it is suitable for producing primary metabolites of the microorganisms. Inside the fermenter, the exponential growth of microorganisms is maintained by providing and changing the conditions and nutrients.

What are the Similarities Between Batch and Continuous Fermentation?

• Both Batch and Continuous Fermentation are two industrial fermentation processes.
• In both fermentations, fresh media are used to provide nutrients.
• In both, an industrial fermentor is used.
• In Batch and Continuous Fermentation, beneficial microorganisms are used.
• Both fermentations produce useful products or biomass as a result of the fermentation process.
• In both, growth conditions are provided for the microorganisms.
• In both, pH, temperature, and aeration are maintained.
• Both are used for the large-scale production in industries.

What is the Difference Between Batch and Continuous Fermentation?

Batch vs Continous Fermentation
Batch fermentation is one type of industrial fermentation in which products are harvested at batch wise while stopping the process at the end of each batch.	Continuous fermentation is another type of industrial fermentation process in which fermentation is carried out for a longer period of time while adding nutrients at the beginning and in between the process and harvesting at regular intervals.
Fresh Media
In batch fermentation, in the beginning, fresh medium is added.	In continuous fermentation, fresh media are added at regular intervals.
Product Harvesting
In batch fermentation, once the fermentation completes, product is harvested.	In continuous fermentation, products and the biomass are harvesting at regular intervals several times while the process is going on.
Process Termination
In batch fermentation, when a batch is ready, process is terminated.	In continuous fermentation, process runs for a long time till harvesting is done several times.
Fermentation Setup
Batch Fermentation setup is not changed from outside once it initiated.	Continuous Fermentation setup can be changed during the fermentation process.
Growth Conditions inside the Fermenter
In batch fermentation, condition will not remain constant.	In continuous fermentation, conditions are kept at constant.
Turnover Rate
In batch fermentation, turnover rate is low.	In continuous fermentation, turnover rate is high.
Use of Nutrients in the Fermenter
In batch fermentation, nutrients are used by the microorganisms in slower rate.	In continuous fermentation, nutrients are utilized rapidly by the microorganisms.
Microbial Growth
In batch fermentation, microbial growth shows in lag, log and stationary phases.	In continuous fermentation, microbial growth exists in exponential phase all the time.
System Type
Continuous Fermentation is an open system.	Batch Fermentation is a closed system.
Fermenter Cleaning
Fermenter is cleaned after the harvesting of a batch in batch fermentation.	Fermenter is not required to clean since continuous adding and harvesting are done.
Size of the Fermenter
Larger size fermenters are used for batch fermentation.	Smaller size fermenters are used for continuous fermentation.
Environmental Conditions inside the Fermenter
In batch fermentation, environmental conditions are less close to the natural environment.	In continuous fermentation, conditions are closer to natural environment.
Suitability
Batch fermentation is suitable for the production of secondary metabolites.	Continuous fermentation is suitable for the production of primary metabolites.
Chance of Contamination
Chance of contamination is less in batch fermentation.	Chance of contamination is high in continuous fermentation.
Initial Cost
Initial cost will be less for the batch fermentation setup.	Initial cost will be high for the continuous fermentation setup.

Summary – Batch vs Continuous Fermentation

Batch and continuous fermentation are two industrially adopted fermentation processes to produce useful products from microorganisms. Batch fermentation is done in batch-wise. Continuous fermentation is done continuously while feeding nutrients and harvesting products at regular intervals. This is the difference between batch and continuous fermentation.

Reference:

1.“Easy Biology Class.” Easybiologyclass. Available here 

Image Courtesy:

1.’Fermentation Science-2’By Visitor7 – Own work, (CC BY-SA 3.0) via Commons Wikimedia