Strach hydrolysis

Is starch agar selective or differential

Differential

What does Starch differentiate between

Species of clostridium, enterococcus, and bacillus

What was the enzyme we were testing for

Amylase which breaks down starch

What types of organisms are more likely to produce the enzyme? Think about where they adapted to live?

Organisms like soil bacteria (e.g., Bacillus), fungi (e.g., Aspergillus), and yeasts (e.g., Saccharomyces cerevisiae) are more likely to produce amylase because they live in environments where starch is a major food source. By producing amylase, these organisms can break down complex starch molecules into simpler sugars that they can then use for energy

Why does starch need to be broken down before it can be used to make ATP

Starch is too big to diffuse through cell walls or go through channel proteins, it’s very easy for smaller molecules to be taken up by cells and used for energy metabolism

What bacteria came back positive for amylase (able to break down starch)

Bc and Ec

How did we test to see if starch was hydrolyzed

We flooded the plate with iodine to see if the bacteria broke down starch or not

What does it mean a portion of the plate turn yellow after a couple minutes of flooding it with iodine

It means it did break down the starch (amylase positive)

What does it mean if portion of the plate stayed purple after a couple minutes of flooding it with iodine

It means it didn’t break down starch (amylase negative)

We know that Bacillus could hydrolyze starch and Staph couldn’t, do you think a lot of organisms that are adapted to live on or in humans would be good starch hydrolyzers?

No, a lot of bacteria that can break down starch are environmental and not human pathogens

Do you think this biochemical test can be definitive for telling the difference between some types of bacteria

yes