Bacteriophage titration

Titration of bacteriophages is one of the methods for determining the activity of bacteriophages in relation to a specific bacterial culture. This method is based on the ability of bacteriophages to lyse (destroy) bacterial cells or form a negative colony in a lawn of bacteria on a solid medium.

To titrate a bacteriophage, it is necessary to prepare a suspension of bacteria that will undergo lysis and a suspension of the bacteriophage in various dilutions. Then the bacterial and phage suspensions are mixed in certain proportions, after which the development of bacterial growth and lysis of bacterial cells under the influence of the bacteriophage are observed.

The activity of a bacteriophage is assessed by the minimum concentration of its suspension, at which complete destruction of bacterial cells or the formation of a negative colony is observed. This is called the 50% lysis concentration (LC50).

Titration of bacteriophage is of great importance in biotechnology, as it allows one to determine the effectiveness of the bacteriophage on bacterial cultures and select the optimal dilution for the experiment.

Titration of Bacteriophage: Determination of activity and efficiency

Introduction

Bacteriophages are viruses that specifically infect and destroy bacterial cells. They are a powerful tool in biological research as well as in the treatment of bacterial infections. To evaluate the activity and effectiveness of bacteriophages, a procedure known as bacteriophage titration is performed. This method allows the concentration of active phage in a suspension to be determined, which is an important step in the production and use of bacteriophages.

Bacteriophage titration procedure

Titration of bacteriophages is carried out by studying their ability to lyse bacterial cultures in liquid nutrient media or form negative colonies in a bacterial lawn on solid nutrient media. This procedure is based on serial dilution of phages and subsequent assessment of the effect on the host bacterium.

Step 1: Preparation of phage dilutions

The original phage preparation is diluted in a series of serial dilutions. Decimal or binary dilutions are usually used for ease of calculation. Each dilution contains a certain concentration of bacteriophage, starting with a high concentration and gradually decreasing it.

Step 2: Preparing the Bacterial Lawn

A layer of bacteria grows on a solid growth medium such as agar, forming a bacterial lawn.

Step 3: Apply phage dilutions to the bacterial lawn

Serial dilutions of the phage are applied to the surface of the bacterial lawn. Each dilution is applied to a separate cell on the agar surface.

Step 4: Incubation

Agar plates containing dilutions are incubated under optimal temperature and time conditions to allow bacteriophages to infect bacteria and cause lysis or formation of negative colonies.

Step 5: Assess the results

After incubation, results are assessed by observing areas of lysis or negative colonies in the bacterial lawn. The number of zones or colonies, as well as their sizes, are related to the concentration of the bacteriophage in the initial suspension.

Step 6: Titre Calculation

Based on the assessment results, the titer of the bacteriophage is determined. The titer represents the number of active phages in a given unit of volume or mass.

conclusions

Bacteriophage titration is an important tool for determining the activity and efficiency of phages. Determining the concentration of active phage makes it possible to establish the dosage and optimal conditions for using bacteriophages in various applications, including biological research and therapy of bacterial infections. Bacteriophage titration is carried out by serial dilution of phages and subsequent assessment of their effect on bacterial cultures.

This method allows you to determine the concentration of active phages in the initial suspension and evaluate their ability to lyse bacteria or form negative colonies on the bacterial lawn. The titration results can be used to calculate the bacteriophage titer, expressed in units per volume or mass.

Titration of bacteriophage is of practical importance in various fields. In scientific research, it helps determine the effectiveness of new bacteriophage isolates or investigate the mechanisms of interaction between phages and bacteria. In medicine, bacteriophage titration can be used to determine the dose of bacteriophages in the treatment of infections or to control the quality of bacteriophages produced on an industrial scale.

In conclusion, bacteriophage titration is an important tool for assessing the activity and efficiency of bacteriophages. This method allows determination of the concentration of active phages and calculation of the titer, which is necessary for various applications of bacteriophages in science and medicine.