Bacteria are already small enough, right? Just in the human digestive tract alone, there are about 500 trillion bacteria, weighing almost 1.5 kilograms.
Bacteriophages
Even such small organisms have viruses that like to parasitize them, and these viruses are called bacteriophages.
Bacteriophages are highly precise, like efficient robots, with nothing on them being redundant, sometimes as simple as just a protein coat enclosing genetic material.
This is a typical tailed bacteriophage (see image above), which is the most common type of bacteriophage (some are tailless). The lower part is its tail, used to recognize bacterial cells and penetrate the cell wall or membrane.
The upper part is its head, where their genetic material is located.
Bacteriophages are among the most common and diverse entities in the biosphere, inhabiting every corner of the Earth, including rich bacteriophage communities on the human body.
Some bacteriophages are harmless to bacterial hosts, but some can kill the host, known as lytic bacteriophages.
When bacteriophages need to infect bacteria, they use their tails to grab onto the bacteria, inject their genetic material into the bacterial cell, replicate inside it, and eventually cause the bacteria to lyse and release the bacteriophages.
With the increasing antibiotic resistance in bacteria, these bacteriophages could be an effective method for humans to combat bacterial infections in the future, as they are harmless to humans.
