Self Quiz on Bacterial Nutrition

1. Which of the following are macronutrients? Micronutrients? Probably not nutrients at all?
Carbon    Sulfur    Aluminum    Iron    Phosphorous    Manganese    Magnesium    Potassium

*    From left to right: macro, macro, none, macro, macro, micro, macro, macro

2. An example of nutrients needing to be in the correct chemical form is that not all bacteria can use the same sugars. What type of medium can we make that takes advantage of this?

*    differential medium

3. An alkalotolerant bacterium will probably grow best at which pH, 7 or 9?

*    Most bacteria grow best near pH 7. Since this bacterium is only tolerant of basic conditions, it probably grows best nearer pH 7.

4.  What type of bacterium grows best with extra carbon dioxide?

*    capnophile

5. How many bacterium emerge from one bacterial spore when conditions improve?

*    one

6. You could probably use two terms to describe a bacterium that requires high salt in order to grow, one specific term and one more general term. What are they?

*    halophile and osmophile

7. A bacterium that grows best under cold conditions is called a

*    psychrophile

8. A bacterium that can grow with or without oxygen is called a

*    facultative anaerobe

9. Superoxide dismutase is an enzyme that breaks down what harmful molecule?

*    superoxide

10. You mash up some grapes and mix them up with some water in a flask. After a day, you do a spread plate and look at the colonies and see a couple of types of bacteria and notice one type that is the most common. Several days later, you plate the cells again and find that the colonies are different, that a different bacterium is most common. You also measure the pH and find that it is becoming more acidic. What is happening?

*    Bacteria are fermenting the sugar in the grapes, making acids, and changing the pH. Other bacteria that were present all along which can grow better at low pH now grow faster and become the most abundant. This is an example of ecological succession, and the bacteria have changed the culture conditions themselves so that now the conditions are optimal for a different set of bacteria.