Why do plaques appear as circles in the lawn of bacteria?
Plaques are clear zones formed in a lawn of cells due to lysis by phage. A diversity of plaque sizes can result if the phage infect cells at different times during the bacterial growth phase: phage that adsorb early make larger plaques than those that adsorb later.
What do clear spots on the lawn of bacteria mean?
Generally when you spot assay with phages in a bacterial lawn you see a clear lysis zone which is the result of bacterial lysis due to the presence of bacteriophages.
What does plaque mean in microbiology?
plaque, in microbiology, a clear area on an otherwise opaque field of bacteria that indicates the inhibition or dissolution of the bacterial cells by some agent, either a virus or an antibiotic. It is a sensitive laboratory indicator of the presence of some anti-bacterial factor.
Plaque forms when bacteria in your mouth mix with sugary or starchy foods, such as milk, juice, soft drinks, bread, pasta and fruit. These bacteria release acids that break down carbohydrates in food and drinks.
Bacterial lawn is a term used by microbiologists to describe the appearance of bacterial colonies when all the individual colonies on a petri-dish agar plate merge together to form a field or mat of bacteria.
The spread of the new viruses is restricted to neighboring cells by the gel. Consequently, each infectious particle produces a circular zone of infected cells called a plaque. Eventually the plaque becomes large enough to be visible to the naked eye.
Department of Biological Sciences, Bridgewater State University, Bridgewater, MA 02325. Corresponding author. Mailing address: Department of Biological Sciences, 131 Summer Street, Connant Science Building 309, Bridgewater State University, Bridgewater, MA 02325. Phone: 508-531-1729. Fax: 508-531-1785.
Virus stocks prepared from a single plaque are called plaque purified virus stocks. To prepare such virus stocks, the tip of a small pipette is inserted into the agar overlay above the plaque. The plug of agar is removed and placed in buffer.
After allowing the bacteria to grow overnight, areas of clear media surrounding the disks indicate that the antibiotic inhibits bacterial growth. The concentration of antibiotic that diffuses into the media decreases with increasing distance from the source.