Muhammad Saleem kalhoro

Damodar Dhakal

Thura Kyaw

Yi Win

A virus that specially infects bacteria.

Ancestral Times- Fermented Milk products.

1.Organoleptic test 2. PH measurement

3. Titration

Lactococcus lactis, was the first infected

Invented by Whitehead and Cox (1935)

LAB like lactobacilus, leuconostoc,

pediococcus, and streptococcus for yoghurt,

cheese and butter milk production.

Virulent phages-largest economic losses of

dairy factories.

Attachment of bacteriophage in host cell

Entry of phage DNA and degradation of host

DNA

Synthesis of viral genomes and proteins

Assemble to form head, tail and tail fibre

Release- cell swells and bursts

Denaturation

1. Sample heated to 94 degree

2. Separate single strand

3. Base for stage 2

Annealing

1. Tempr lowered to 54 degree

2. Synthetic DNA fragments are added as primer

3. Form ionic bond with the template

Extension

1. Again heated to 72 degree

2. Polymerase enzyme is added

3. Bind the primer-templete hybrid

4. Synthesis of DNA

These three steps are repeated to produce the more DNA

Starter Culture

(Selected strains)Fermentation Vat

•Bacteriophage

attack

•Enhance fermentation

•Improve flavor texture

•Culture

multiplication

•Several fold

decrease in

bacterial culture

•lysis of infected host

•Delay of Acidification

•Quality changes

•Failure of fermentation

Bacteriophage-Total absence is impossible.

Host specific (so big collection of culture is

needed)

If phage detected then milk directed to

byproducts production, buttermilk, smp.

Adsorption interference,

1.production of extracellular polysaccharides

2.Bind in the capsular form- physical barrier.

3.↑capsule thickness than phagetail-↓phage

infection

DNA injection blocking

1.Calcium dependent cell wall

3.Translocation of host DNA

4. Prevents entering cell cytoplasm

restriction/modification,

Introducing two enzymes system

Site specific-restriction endonuclease, helps in

the digestion of phage DNA

Methylase-protects host cell by modifying DNA.

abortive infection,

Encompasses a range of mechanisms that

interfere with

Genome replication

Transcription

Translation

Packaging or assembly of phages.