Microbial Nutrition and Growth Flashcards
What are macronutrients?
Elements required in large amounts to build macromolecules.
What are the 4 organic macromolecules made of?
Protein: CHON(+S) - polymers of amino acids
Lipids: CHO(+P) - fatty acids and glycerol
Carbohydrates: CHO(+N) - sugars
Nucleic acids: CHONP - nucleotides
What inorganic ions are included in the macronutrients? what do they do?
K+: enzymes required in protein synthesis
Fe2+: Cytochromes (e- carriers)
Mg2+: stabilize membranes and nucleic acids
Ca2+: stabilize cell wall and plays a role in heat stability of endospores
What are micronutrients? Give 6 examples.
Elements required in very small amounts (trace elements) and serve as cofactors for enzymes. (e.g. Mn, Zn, Co, Ni, Cu, Mo)
What are growth factors?
small organic molecules required for growth; must be added to medium to grow it in lab
What are three classes of growth factors?
- Amino acids: 20 needed for protein synthesis
- Purines and Pyrimidines: AGTCU
- Vitamins: small molecules used to make organic cofactors, non-protein components required by some enzymes
What bacteria require growth factors, and what bacteria doesn’t require growth factors.
No growth factor requirements: E. coli
Many growth factor requirements: Leuconostoc mesenteroides (requires all 20 amino acids, purines+pyrimidines, and 10 different vitamins)
Where is H and O typically found?
Found in H2O and organic media components.
Where is P found?
Provided as phosphate salt (PO4^3-) as it is acquired that way in the environment. In freshwater systems, it is often limiting.
What is limiting nutrient?
A nutrient that stops growth when it runs out, despite the other nutrients present
Where does inorganic, organic and atmospheric N come from?
inorganic N: provided as salts and must be reduced to amino groups to make amino acids
organic N: provided as N rich organic molecules (e.g. amino acids/short peptides) and does not need to be reduced
atmospheric N: N2 is reduced to 2NH3 due to nitrogen fixation and is used to make amino acids, though energetically expensive. (only done by some bacteria and archaea, never eukaryotes)
What does inorganic and organic S come from?
Inorganic S: provided as salts and must be reduced to the level of S2- to make amino acids (process known as assimilative sulfate reduction)
Organic S: pre-made amino acids, less energy to assimilate.
What is a heterotroph?
A group of organisms that use organic atoms (e.g. organic acids, alcohols, carbohydrates, amino acids) where one more C is reduced.
What is an autotroph?
Use of inorganic carbon (CO2) as their sole source of carbon. Requires energy to assimilate, typically obtained through photosynthesis.
What is metabolism?
The sum total of all the chemical reactions (anabolism, catabolism) that occur in a cell.
