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Pure Culture

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What is a Pure Culture?

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The environment around us consists of a mixed population of microbes. Each of these groups of organisms contributes to the ecology. However, ever wondered how are the studies carried on such microbes? Is it feasible to study and experiment with all of these together? Well, no. It isn’t. To carry out the studies on these microbes, it is essential to dissect the mixed culture into a pure culture. 


Now, what is a pure culture? What purpose does it serve? What is a pure culture microbiology? What are the pure culture methods or pure culture techniques?  Let us help you understand all these terms in detail. 


Pure Culture Definition

Put down in simple terms, pure culture is defined as a laboratory culture that contains just one species of organisms in microbiology. Microbes are usually in the mixed culture. But, the pure culture can be derived from it through the transfer of a bit of its sample in the new and sterile growth medium. 


The process of pure culture isolation usually takes place by dispersion of cells across the surface medium. This mainly involves thinning of the sample before it is inoculated into a new medium. There are several pure culture techniques utilized by scientists to carry out the process of creation of discrete colonies of pure microbes. 


The techniques of isolation of the pure culture were primarily developed by Robert Koch during the mid-19th century. Microbiologists of those times readily adopted these methods for the production of a single strain of the organism. 


The inculcation of such techniques of pure culture led to bacterias characterization that was responsible for causing anthrax, tuberculosis, and such major diseases. Following this, scientists developed similar procedures for protozoa, fungi, and algae. 


Are you wondering that do pure culture organisms serve any commercial purposes? Well, yes, they do. It is mainly used for commercial fermentation purposes mainly including yogurt, alcohol, citric, lactic acid, and several other beverages for many years now. The pure culture technique has also contributed to the development of several vaccines and antibiotics. 


Pure Culture Collections:

These are basically a resource and method of preserving the genetic resources of these organisms. The collection of pure culture organisms varies widely depending on size and some specializations as well. These have gained importance over the years due to their authenticity, reliability, and practical uses. For culture, several national federations are present across various countries, and detailed information is available about the same. 


How is the Purity of Culture Assessed? 

The assessment of the purity of culture is carried out through different methods. These are as follows:

  • The same cultural characteristics are shown on the media obtained in the isolated colonies of pure culture organisms. 

  • The same culture organisms look alike when observed under the microorganisms. This means that they get the same stain and have the same morphology. 

  • Just like similar biochemical results the isolated colonies of pure culture perform identically, i.e., separately. 

Biochemical Characteristics of Pure Culture:

  • The mixed culture organisms show different results in the case of experiments. 

  • The pure culture organisms show similar results in the case of experiments. 

What is the Importance of Pure Culture in Microbiology?

  • The organisms of pure culture can be grown, tested, characterized, and identified. 

  • It is feasible to study the clinical aspects and physiology of pure culture organisms. 

  • Irrespective of the number of times the test is done, the same results will be obtained for a particular culture of organisms during any sort of test. 

  • Spontaneous mutation occurs slowly in the case of pure culture, and moreover, the clone so formed is identical in all forms and aspects. 

Pure Culture Techniques Microbiology

The various techniques used to obtain pure culture in microbiology are as follows:

  • Sterilization process for media and glassware

  • Dispersion of individual cells takes place across the medium

  • The thinning process of samples is carried out multiple times before the inoculation of fresh media takes place. 

FAQ (Frequently Asked Questions)

1. What are the Sterilization Techniques Involved in Pure Culture?

Ans: The various types of sterilization techniques involved while carrying out the process of pure culture in microbiology are as follows:

  • Sterilization with moist heat

  • Sterilization with dry heat

  • Filtration

  • Sterilization using flame

  • Biosafety cabinets for laminar airflow

2. What are the Isolation Methods for Pure Culture?

Ans: The isolation of pure culture can be done in the following ways.

  • Techniques of streak plate

  • Techniques of pour plate

  • The technique of serial dilution

  • The technique of spread plate

  • Enrichment method

3. What are the Various Conditions Which Affect the Sample Culture?

Ans: The various conditions affecting the sample culture are listed below:

  • Water

  • Nutrients

  • Oxygen

  • Temperature

  • Acidity

  • pH

  • Chemicals

  • Light