Chapter 8, Problem 1AQ

What causes the viral plaques that appear on a bacterial lawn to stop growing larger?

Summary Introduction

To determine: The causes of the viral plaques that appear on a bacterial lawn to stop growing larger.

Concept introduction:

The bacterial virus grows in a solid agar medium and animal virus culture in a liquid broth. The host bacterial cell is inoculated in the liquid or solid agar medium and then it is inoculated with a suspension of virus. The culture medium contains required nutrients and antimicrobial agents for growth of host cell and to prevent the microbial contamination.

Explanation of Solution

The animal and bacterial viruses need a culture medium for their growth which contains the necessary nutrient medium. The bacteria and virus is inoculated into the growth medium to cause an infection. After infection, the virus can multiply itself in the host bacterium. A plaque is formed over the bacterial growth as lawn over some period of time, it indicates the presence of destructed host cell with new virus particles.

The bacterial growth has occurred in a particular time period after that it stops its growth slowly because the insufficient nutrient medium and some unfavourable condition. This can lead to stop the growth of plaques of the bacterial lawn. Hence the viral production has ceased without the presence of the active bacterial host cell.