lux M and B lab

What is quorum sensing?

Bacteria communicate using signaling molecules to coordinate gene expression.

What is a ligand in the BacTalk activity?

A signaling molecule bacteria produce and detect.

What happens at low ligand concentration?

Too little signal is present, so the bioluminescence response is usually off.

What happens at high ligand concentration?

Enough signal accumulates to activate the response in bacteria with working signaling and light-producing genes.

What does wildtype mean?

A strain with the normal, functional genes and proteins.

What is the role of LuxM?

LuxM helps produce the signaling molecule (ligand).

What is the role of LuxB?

LuxB is part of the luciferase system required for light production.

Why can a luxM- mutant glow near wildtype?

Wildtype can supply diffusible ligand, allowing the mutant to activate its response if its other genes work.

Why can't a luxB- mutant produce light?

It lacks functional LuxB, so it cannot complete the light-producing process even if it receives signal.

What is co-plating used to test?

Whether one strain's diffusible signal can affect another strain's bioluminescence.

Why are co-plated strains kept apart?

They must not touch, so effects can be attributed to a diffusible signal crossing the agar.

What does a glowing wildtype strain show?

It can produce signal, detect the signal at sufficient concentration, and produce light.

Can a non-glowing strain be identified from glow alone?

No. Different mutations can prevent light, so additional co-plating tests are needed.

What happens to luxM- alone at low ligand?

It cannot make its own ligand, so it generally does not activate the response.

What happens to luxM- with wildtype at high ligand?

Wildtype supplies ligand; luxM- can glow if its signal-response and light-production machinery work.

What happens to luxB- at high ligand?

It may receive the signal, but it cannot produce bioluminescence without functional LuxB.

What is the difference between signaling and response?

Signaling produces/releases the ligand; response is the downstream effect, such as light production.

If a strain receives signal but does not glow, what might be wrong?

A downstream response or light-production gene may be defective, such as luxB.

Why does ligand concentration matter?

The response depends on whether enough signal accumulates to activate the pathway.

What is the key difference between luxM- and luxB-?

luxM- cannot make its own signal; luxB- cannot produce light even when signal is available.