The word
“bacteriophage” literally means “eats bacteria”, and is a
Greek term coined by the French-Canadian scientist named Felix
d’Herelle. A bacteriophage is a virus that only destroys a very
specific host bacterium by a process known as “lysing”. Bacteriophage is also known simply as ‘phage’.
Unlike antibiotics and other
chemicals, phages will not kill other “good” bacteria,
beneficial micro flora, and have no negative impact on other forms
of life or the environment.
While phages
are technically classified as
viruses, they are very different from the dangerous viruses we are
familiar with such as those that cause AIDS or Influenza. Phages are different because they can
only harm specific bacterial cells; they are harmless to humans,
animals, and plants. They are considered a helpful part of our
natural environment because they keep the population of dangerous
bacteria in check.
When a bacteriophage encounters a
specific bacterium or ‘host’, it breaks through the bacterial
cell wall and effectively lyses or ‘kills’ the bacterium.
During the process of lysing, the phage injects its DNA into the
bacterium, which begins to replicate as a new phage. Once a
bacterium is lysed by a phage, the bacterium becomes host to a
reproduction process that results in the release of additional
phages. These new phages are capable of lysing more bacteria. This
process continues until the host is no longer present, after which
the phage decomposes into the soil.
Lysing can be described in three
basic phases:
- Adsorption occurs when a phage
encounters a bacterium, attaches its tail fibers, and injects its
own DNA into the bacteria.
- New phage begins replicating and
assembling within the bacterial cell, multiplying at a steady
rate.
- Finally, lysis is complete when
the cell bursts and releases about 100 new phage into the
environment to carry on the process.
Each time a
bacterium is infected by a phage, approximately 100 new phages are
produced and released into the immediate vicinity. This process
continues until all available bacteria are destroyed.
The cycle — time from the moment
of infection of bacterium to a new generation of phages lasts from
15 till 40 minutes, it depends upon the phage type.
Advantages of bacteriophages:
Bacteriophage is a natural killer of
the quantity of bacteria. It means that they always destroy
pathogenic germs since the very existence on the Earth. . (People simply were not aware of
those facts).
- Phage is able to kill bacteria
resistant to antibiotics.
- Phage evolves constantly.
- Phage does not cause any side
effects.
- Phage does not
cause such
an active bacterial resistance as
antibiotics do.
- Phage strengthens immunity of the
organism, inhibiting pathogenic micro flora.
- Phage is compatible with any other
medical preparations.
- Phage can be used by pregnant women,
nursing mothers and by babies.
- Fields of applications of
bacteriophages
Phages are successfully used not
only in medicine and veterinary, they are used in agriculture (for
defense of plants, animals and finished products from bacterial diseases and decay).
Phages are used
for sanitation and decontamination of surgery, food processing and
for air purification indoors.
