20 - plaque assay to determine bacteriophage concentration

what is a bacteriophage?

a virus that infects/replicates within a host bacteria

how to do phage replication test?

1. aseptically transfer a pure suspension of coliphage to a broth culture containing the host bacteria

2. transfer that mixture to a warm/soft/semisolid agar

a T4 bacteriophage is also known as

a coliphage, because its host is e. coli

what is a plaque and a PFU?

a plaque is a clear zone of cell death around a culture, usually caused by infection.

a PFU (plaque forming unit) is a single infectious viral particle capable of forming a plaque when introduced into a cell culture

how do you record the results of a plate that has fewer than 30 PFU or more than 300 PFU?

<30 = TFTC (too few to count)

>300 = TNTC (too numerous to count)