Bacteriophages Exposed

Illustration of life cycle of bacteriophages
Lytic Cycle vs. Lysogenic Cycle courtesy Texas Gateway for Online Resources

ABSTRACT - A bacteriophage, or phage for short, is a virus that infects bacteria. They are organisms that have played and continue to play a key role in bacterial genetics and molecular biology. Being the most prevalent types of viruses, bacteriophages vary a lot in their shape and genetic material. In the process of hijacking a cell, the virus recognizes and binds to a host cell via a receptor molecule on the cell surface then the virus or its genetic material enters the cell. The viral genome is copied and its genes are expressed to make viral proteins. Completed viral particles exit the cell and can infect other cells. The lytic phage cycle is when phage infects a bacterium, hijacks the bacterium to make lots of phages, and then kills the cell by making it explode (lyse). The lysogenic cycle is when the phage inserts its DNA and it is passed on along with the cell’s own DNA. The goal of the present study was to isolate and characterize bacteriophage specific for Mycobacterium smegmatis from the soil. After conducting the experiment, it is obvious that the phage are lytic because of the plaques in the plates.

Bacteriophages Exposed

Bacteriophages were discovered in 1915 by the English bacteriologist Frederick W. Twort. A bacteriophage, or phage for short, is a virus that infects bacteria. They are fascinating organisms that have played and continue to play a key role in bacterial genetics and molecular biology.

Being the most prevalent types of viruses, bacteriophages vary a lot in their shape and genetic material. They’re a very interesting subject to study because of the their ability to kill their bacterial hosts, which makes them potential candidates to be used as tools for cures, and because of the clarity they have brought to molecular processes, including the makeup of DNA and the effects of viruses on cells.

In the process of hijacking a cell, the virus recognizes and binds to a host cell via a receptor molecule on the cell surface then the virus or its genetic material enters the cell. The viral genome is copied and its genes are expressed to make viral proteins. New viral particles are assembled from the genome copies and viral proteins. Then, proteins of the capsid (head) assemble around the viral genome, forming a new viral particle with the genome on the inside (encased by the capsid). Finally, completed viral particles exit the cell and can infect other cells.

There are two types of phage life cycles: lytic and lysogenic. The lytic cycle is when phage infects a bacterium, hijacks the bacterium to make lots of phages, and then kills the cell by making it explode (lyse). The lysogenic cycle is when the phage infects a bacterium and inserts its DNA into the bacterial chromosome, allowing the phage DNA to be copied and passed on along with the cell’s own DNA. An important thing to note is that a phage can come out of the lysogenic cycle and go into the lytic cycle.

The goal of the present study was to isolate and characterize bacteriophage specific for Mycobacterium smegmatis from the soil. After conducting the experiment, it is obvious that the phage are lytic because of the plaques in the plates. Researching bacteriophages has and will continue to be a valuable resource for mankind because of the information it provides us about viral diseases and infections that have proven to be harmful or even fatal.

WORKS CITED

“Bacteriophages .” Khan Academy, https://www.khanacademy.org/science/biology/biology-of-viruses/virus-bio...

Grath, Stephen Mc, and Douwe van. Sinderen. Bacteriophage: Genetics and Molecular Biology. Caister Academic Press, 2007.

Loc-Carrillo, Catherine , and Stephen Abedon. “Pros and Cons of Phage Therapy.” Taylor & Francis, 1 Mar. 2011, https://www.tandfonline.com/doi/abs/10.4161/bact.1.2.14590

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