Microbial Growth & Nutrition Flashcards
How do bacteria multiply?
Binary fission
What is a direct measurement of microbial growth?
Viable cell count
What is the indirect measurement?
Optical density
Name the physical requirements for growth
- Temp
- O2
- Osmotic pressure
- pH
- Light
Optimal temperature for E.coli to grow is…
39 degrees
What is a psychrophile?
A bacterium that can grow under very low temperatures
What is agar?
Unbranched polysaccharide from red algae cell walls.
What is optical density?
Measuring light absorption to determine concentration of viable organisms.
Which method to determine growth doesn’t take into account dead cells?
Direct growth, viable cell count.
What is a mesophile?
Bacteria that grow at an optimum temp of 38/39 degrees.
Why is intracellular pH kept as close to neutral?
Preserve integrity o macromolecules within bacterial cell.
Which salt halophiles require to grow?
NaCl
Which micronutrient is needed for cellular respiration?
Iron
What are the 3 types of culture media?
- Selective
- Differential
- Enrichment
