Restriction enzymes was discovered by

• Restriction enzyme:
It is also called restriction endonuclease.
It is a protein produced by bacteria that cleaves DNA at specific sites along the molecule.
In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms.
Restriction enzymes can be isolated from bacterial cells and used in the laboratory to manipulate fragments of DNA.
Restriction enzymes were discovered and characterized by molecular biologists Werner Arber, Hamilton O. Smith, and Daniel Nathans. 

• Work of  Restriction enzyme:
A bacterium uses a restriction enzyme to defend against bacterial viruses called bacteriophages, or phages.
When a phage infects a bacterium, it inserts its DNA into the bacterial cell so that it might be replicated.
The restriction enzyme prevents replication of the phage DNA by cutting it into many pieces.
Restriction enzymes were named for their ability to restrict, or limit, the number of strains of bacteriophage that can infect a bacterium.

🔴Additional Information:
 Hans Berge: 
He invented an electroencephalogram.
It is an instrument that measures and records brain-wave patterns.
electroencephalogram, commonly abbreviated EEG.

• Selman Waksman:
He was a Ukrainian-born American biochemist.
After the discovery of penicillin, he played a major role in initiating a calculated, systematic search for antibiotics among microbes.
Won 1952 Nobel Prize for Physiology or Medicine

• Alexander Fleming:
He was a Scottish physician-scientist.
He was recognized for discovering penicillin.
He won the 1945 Nobel Prize in Physiology/Medicine.