Cyanophage and its Details

Cyanophage and its Details

Cyanobacteria

ž Cyanobacteria are microscopic, photosynthetic, aquatic bacteria.

ž It is generally found in fresh water, Lake, Ocean, Streams, Moist soil and rock.

ž Cyanobacteria is also called as blue-green algae and also called as cyanophyte.

ž They are aquatic, photosynthetic, prokaryotic bacteria so its name was renamed as Cyanobacteria.

ž Cyanobacteria have an internal membrane and flattened sacs called as thylakoids.

ž In thylakoids, photosynthesis process is carried out.

ž Cyanobacteria are able to fix atmospheric nitrogen and hence can be useful in agriculture.

ž Examples of Cyanobacteria are Spirulina, Nostoc and Anabaena.

ž Cyanobacteria are microscopic in nature but its colony may be large enough. When its colony grows it can cause large blooms.

ž The blooms may be harmful to Human beings, Plants, Animals and aquatic life.

ž These Cyanobacteria forms a layer on the surface of the water in various colours like green, blue, brown or red.

ž This layer causes depletion of oxygen in the water and affects aquatic life.

ž It may also release some toxins in water and affect taste and odour of water.

Cyanophage

ž Cyanophage is a virus that infects Cyanobacteria. Here phage means the bacteria that infect the bacterial cell.

ž Cyanophage uses Cyanobacteria for its replication and multiplication.

ž Cyanophage is classified in a bacteriophage family that is Myoviridae, Podoviridae, and Siphoviridae.

ž Cyanophage was first discovered in 1963 by Safferman and Morris they discovered the first Cyanophage and named it as LPP -1.

ž The three cyanobacteria that are Lyngbya, Plectonema and Phormidium were attacked by this virus, so this virus was named as LPP – 1 by using first letters of these genera.

ž Further many serological strains of LPP virus were isolated from all over the world and hence named as LPP-2, LPP-3, LPP-4, LPP-5.

ž The eutrophic lakes and polluted water supports the luxurious growth of Cyanobacteria and hence cyanobacteria form a bloom which can result in mortality of aquatic life. So here Cyanophage helps in controlling such blooms.

ž Cyanophage has Icosahedral head and short tail, similar to T3 and T7.

ž They may differ in morphology as well as physio-chemical properties.

ž Tail of Cyanophages may be contractile or non – contractile.

ž N-1 group of cyanophages are similar to T2 and T4 phages.

ž Group G-III and D-1 of cyanophage are serologically similar to T phages but there is no relation between them.

Morphology of Cyanophage – LPP -1 Group

ž Cyanophage has Icosahedral head and short tail, similar to T3 and T7.

ž They may differ in morphology as well as physio-chemical properties.

ž Tail of Cyanophages may be contractile or non – contractile.

ž N-1 group of cyanophages are similar to T2 and T4 phages.

ž Group G-III and D-1 of cyanophage are serologically similar to T phages but there is no relation between them.

Growth Cycle of Cyanophage

ž Cyanophage show one step growth curve. The growth curve of cyanophage is similar to T4 but the latent and rise period is different.

ž Multiplication of LPP-1 is carried out in the following manner.

  1. Adsorption – Virus is attached or absorbed on the surface of the host cell.

2. Injection – Genome of phage is injected into the host cell and protein coat is left outside the cell. DNA injection mechanism is unknown.

3. Reduce protein synthesis – As soon as genome enters the rate of protein synthesis of the host cell is reduces and blocked.

4.  Multiplication – The cyanophage starts to multiply.

5. Assembly – The viral nucleic acid and protein coat starts to assemble and form a procapsid.

6.Release – After assembly, the cyanophage gets the release from the host cell by lysis of the cell.

Important Notes

ž Hereafter insertion of genome three types of proteins are formed and that is

  1. Earliest proteins – These proteins are formed immediately after genome enters.
  2. Early proteins – Early proteins are formed after 2 hours of entry of genome till lysis of the cell.
  3.  Late proteins – They are formed after 4 hours of infection until host lysis.

ž Further degradation of host cell takes place after 3 hours of infection.

ž The degraded DNA material of host cell is used for the synthesis of the viral genome.

ž The latent period of LPP-1 and N-1 is 7 hours.

ž The plaque forming units that are PFU may also vary from virus to virus.

ž Burst size – It is a number of phages release after multiplication and Replication of viruses from the host cell.

ž The burst size of the virus may also vary.

  1. LPP-1 is 350 PFU
  2. AS-1 is 50 PFU
  3. N-1 is 100 PFU
  4. SM is 100 PFU

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