Survival strategies

17 important questions on Survival strategies

How does efficient survival strategies work?

Efficient survival strategies based on continuous monitoring of the environment and activation of adaptive stress responses.

They have very good sensors that can monitor the changes in nutrients, pH, temperature and pressure. When a change is monitored there is a regulating system that can act on these changes.

What happens when there is a stress imposed on the micro-organism?

Activation sensors > activation regulators > activation genes > stress defense

Substrate binds to receptor and activates response.

This is smart because if the stress is not there there does not have to be a response.   

super fast process

What is a danger for food safety on adaptive responses of micro-organism?

If a pathogen is in the adaptive state it can be more resistant and survive in the stomach.
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Why is listeria often chosen as a model organism?

  • Because of its ability to tolerate adverse conditions such as low Aw and low temperature
  • Insight in listeria stress adaptation in terms of its improved survival in foods (because it is one of the most dangerous)
  • Designing safety or extended shelf-life of minimally processed food (if you know what you need to do to kill thisone it will probably also work for others)

Why does lysteria monocytogenes have a high mortality rate?

This is because they can invade the body of the host. And also the brain and the placenta. Which can cause death and abortion.

What are the 2 temperature proteins made by the sigma factor?

Cold shock and heat shock proteins.
Cold shock: Maintaining the overall conformation of messenger proteins. (due to low temperature more enhanced hydrophobic interactions which may cause difference in conformation of rna and proteins) cold shock proteins protect rna and proteins form this.

Heat shock: They repair proteins damaged by the stresses. Or of they are to damaged they cut them away and make new ones.  Because damaged proteins may inhibid cell functioning.

What is a adaptive responce?

Due to a pathogen being exposed to a damaging temperature they can survive better.

What is cross protection?

Due to pathogen being exposed to a damaging stress it can survive better in a condition with an other killing stress

How does the sigma B factor work?

If there is a stress in Lysteria. ist sensens thees stress. A singal is made and this activates sigma B. Then the transcription of certain genes regulated by sigma b starts. These proteins transcripted from the specific part of DNA protect the cell.

What does Listieria do to survive low water activity?

It increases the concentration of a salt that does not interfere with processes. This is called osmo-adaptation.
These salts are glycine betaine and carnitine

How are the transporters involved in osmoadaptation of L. momocytogenes called?

GBU: for betaine
BetL: for betaine
OpuC: for carnitine

Becasue 2 poms use ATP they can work against the stream and cope with low water activity

What is the function of osmo-adaptation?

  • balancing osmotic disturbance
  • stabilize enzymes
  • stabilize the membrane
  • protect cells during freezing
  • stimulate low temperature adaptation

How can listeria deal with acid/low pH?

It has an glutamate decarboxylase system (GAD). This system removes a proton (H+). This makes increases the pH in the cell. Therefore the listeria will not die.

Is there a difference in glutamate decaroxylase between stains of listeria?

YES!

How does low temperature adaptation go?

The cold shock proteins (CSPs).
They can protect the RNA from deformation and therefore the ribosomes are able to transcribe proteins. 

A micro-organism can have different types of cold shock proteins.

How can listeria with a mutant in the chaperon protein survive in higher stress conditions?

The repressor of ClpP protein (that gives a higher stress resistance) in inactivated. So there will be a lot of ClpP present.
This makes that the bacteria did not have to be in a extreme condition in order to make it. It already has the ClpP and therefore is more resistant.

Why does the original nor resistance listeria have flagella and the new type not?

Fla proteins were sudden to make flagella but also to suppress ClpP. So the micro-organism with higher resistance does not have the flagella because there is a mutant. But is will therefore also not have the suppressor and therefore it will be able to grow in more extreme conditions.

The question on the page originate from the summary of the following study material:

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