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Difference between Batch and Continuous Fermentation

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Fermentation: An Introduction

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The fermentation process usually occurs in microbes and this process is used to form various products. For this, large tanks are used known as bioreactors in which all the components such as nutrition, and microbes are mixed and products allowed to be formed in controlled conditions. To learn more about fermentation, batch and continuous fermentation and the difference between them, continue reading through the following article.

What is Fermentation?

Fermentation is the process of oxidation of organic material in absence of oxygen. It is a metabolic process that occurs in microbes.

Types of Industrial Fermentation

There are mainly three types of fermentation:

  • Batch fermentation

  • Fed-Batch fermentation

  • Continuous fermentation

Batch Fermentation

In batch fermentation, all the components are mixed at once then the reaction undergoes without any further intake from outside. During the whole process, no extra nutrients are added. It is a closed system because all the components are added at once and no other components are added in between the process of fermentation.

There are three phases in the batch fermentation process - lag phase, exponential phase, and stationary phase.

  • In the lag phase, microbes adapt to the environment of the culture and

  • In the exponential phase, the microbial cells grow rapidly and consume most of the nutrients and the last phase is

  • The stationary phase is when the growth of microbes stops due to the consumption of all nutrients. It is the simplest type of all industrial fermentation.

The batch fermentation diagram is given below.

Batch fermenter


Batch Fermenter

Fed-Batch Fermentation

  • It is a modification of batch fermentation.

  • In this nutrition is added aseptically and the amount of liquid culture in the bioreactor increases as the culture is added systematically.

  • It is a type of semi-open system.

  • It yields a better result than batch fermentation.

  • After consumption of early substrate continuous and constant nutrition is added.

Fed-batch fermenter


Fed-batch Fermenter

Continuous Fermentation

  • It is a type of fermentation in which constant addition and flow of solution occur.

  • Microorganisms and sterile nutrients are added continuously and the nutrient solutions and microbes are transformed simultaneously.

  • It is a type of open fermentation system in which comments can be added and removed in between the process.

  • There are many methods of continuous fermentation.

Continuous fermenter


Continuous Fermenter

Similarity between Batch Fermentation and Continuous Fermentation

There are many similarities between batch and continuous fermentation. In both batch fermentation and continuous fermentation, development conditions are provided from the outside. In both, temperatures, pH and aeration are maintained. In both types of fermentation useful products are formed.

Difference between Batch and Continuous Fermentation

There are many differences between batch and continuous fermentation.

Fed-Batch Fermentation

Continuous Fermentation

It is a closed system.

It is an open system.

In this type of fermentation, microbes are grown in a limited supply of nutrition

In this type of fermentation nutrients and microbes are added continuously

Nutrients are the limiting factor because they are added only at once int be bringing the process.

Nutrition is not the limiting factor as it is added continuously throughout the process.

Chances of contamination are less .

Here chances of contamination are more

Yield is less

Yield is more

Lag, log, and stationary phases are there

The lag and log phase is only there

The whole process is stopped when the product is formed.

The process continues and the product is removed as soon as it is formed.

Large fermenters are used .

Small size fermenters are used

Nutrients are consumed at a slower rate .

Nutrients are consumed rapidly.

Important Questions

1. Which phase is longer in continuous fermentation?

Ans: Exponential phase is of longer duration in continuous fermentation as nutrients are continuously being added to the solution. This phase shows the maximum growth rate. This phase is also known as the log phase.

2. What are the limitations of fermentation?

Ans: Fermentation is a slow and continuous process and it requires more energy. and resources.

3. Which microorganism is responsible for fermentation?

Ans: Mostly lactic acid bacteria of several genera, including lactobacillus, streptococcus, yeast, and another fungus also used for the fermentation process.

Fun Facts about Fermentation

  • The fermentation process is one of the important processes as it enhances the nutritional value of food.

  • Various types of expensive dishes are made by the fermentation process.

  • Wine or alcohol is also made by the fermentation process.

  • Fermentation is also a method of preserving food items.

Practice Questions

  • Does fermentation require oxygen?

  • Why is temperature important in the fermentation process?

  • What factors speed up the fermentation process?

  • What is batch culture used for?

  • What are the advantages of batch culture?

Key Features

  • The fermentation process is used to make various products.

  • There are three types of industrial fermentation.

  • Batch fermentation is the simplest type of fermentation and batch-fed is a modification of batch fermentation.

  • In this article, we have also studied batch culture and continuous culture.

  • There are differences between continuous fermentation and fed-batch fermentation like fed-batch is a closed system whereas continuous fermentation is an open system.

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FAQs on Difference between Batch and Continuous Fermentation

1. Why is a continuous culture called an open system?

Continuous culture is called an open system because the constant internal condition is maintained throughout the culture by adding nutrition, microbes and removing waste. Here the cell volume and cell culture are maintained constant by adding a fresh and sterile medium. There are only two phases in the continuous culture system: lag and log phase. In the log the phase growth is rapid.


In this type of fermentation growth limiting nutrients can be maintained at a steady concentration, which permits the growth of microbes at a submaximal rate.

2. What factors can affect the fermentation process?

Various factors affect the fermentation process such as temperature, pH, acidity, ethanol, and the availability of nutrition.

  • Temperature - The temperature required depends on the type of microbe. The lactic acid bacteria require higher temperatures than yeast. The temperature should be above 18°C to allow the growth of bacteria.

  • pH - The optimum pH for the growth of microbes depends on the type of strain. Ph electrode is used to detect the fermentation process, which is continuously used to measure and record the ph change.

3. Write the benefits of fed-batch fermentation.

There are various benefits of fed-batch fermentation. Some of the benefits are given below:

  • In this, we can control the growth rate of microbes

  • In this, we will also have control over metabolites.

  • And here we can also control the transfer of oxygen by inlet feeding rate.

  • Fed-batch fermentation is more productive because of the controlled addition of raw material.


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