3.1: Microbial Growth and Nutrition - Microbial Nutrition and Culture Media

Question 1

what are Macronutrients, what elements are they? what percent of the dry weight of the cell does it make up?

Answer 1

• Elements required in large amounts to build macromolecules
• the building blocks of cell material
• CHONPS makeup > 90% of the dry weight of the cell

Question 2

what are the building blocks of proteins, what elements make it up and how much of cell’s dry weight does it make up?

Answer 2

• building blocks = amino acids.
• CHONS
• > 50% of cell dry weight

Question 3

what are the building blocks of carbohydrates and what elements make them up

Answer 3

• building blocks =sugars
• CHON

Question 4

what are the building blocks of lipids and what elements make them up

Answer 4

• building blocks = fatty acids and glycerol (backbone)
• CHOP

Question 5

what are the building blocks of nucleic acids and what elements make them up

Answer 5

• building blocks = nucleotides
• CHONP

Question 6

Which element is the greatest contibuter to a cell’s dry weight?

Answer 6

Carbon (50% of dry weight)

Question 7

what macromolecule is the greatest contributer to a cell’s dry weight?

Answer 7

• protein (55%)

Question 8

what do the other macronutrients -iorganic ions (K, Mg, Ca, Fe) often serve as?

Answer 8

• often serve as metabolic co-factors
• they are the non-protein component required for enzyme function

Question 9

what’s an example of how each of the inorganic ions (K, Mg, Ca, Fe) are needed for cell functions

Answer 9

• enzymes in protein synthesis need K+
• Cytochromes (e- carriers in the ETC) need Fe2+
• Mg2+ stabilizes membranes and nucleic acids
• Ca2+ helps stablize cell walls and plays role in heat stability of endospores

Question 10

what are all the Macronutrients (including the main ones and the inorganic ions)? what 2 are not always needed? why?

Answer 10

• CHOPKNS CaFe Mg
• Ca and Fe (cafe) not always needed bc ABC transporters allow for accumulation of them.

C. HOPKNS CaFe is Mg (Mighty good).

Question 11

what are Micronutrients? what’s their function and what elements are they?

Answer 11

• Elements required in very small amounts (trace metals)
• Usually serve as cofactors for enzymes
• Mn, Zn, Co, Ni, Cu, Mo

Min, zin, CoNiCuMo

Question 12

do micronutrients need to be added to media?

Answer 12

No, expect they’ll be picked up in trace amounts by bacteria.

Question 13

what is the only thing Se is needed in such a small amount for?

Answer 13

• Se is required to make the unusual amino acid selenocysteine.

Question 14

what are growth factors?

Answer 14

Small organic molecules required for the growth of some organisms.
-those that don’t have the metabolic ability to make them themselves from macronutrients, need the growth factors to be added to the medium for them to grow.

Question 15

what are the 3 classes of growth factors and what they’re needed for

Answer 15

1. amino acids - 20 amino acids are needed for protein synthesis.
2. Purines and pyrimidines: A,T, G, C and U are needed to make nucleotides -the building blocks of DNA and RNA
3. Vitamins -small molecules used to make organic cofactors, (non-protein components required by some enzymes).

Question 16

what happens when growth factors are added for bacteria that doesn’t require them (can make them from scratch)

Answer 16

• May promote growth, as making growth factors from scratch requires lots of energy, so if they’re given thats more favorable, more energy can be put towards growth.

Question 17

what’s an example of bacteria that have no growth factor requirements?

Answer 17

• E. coli

Question 18

what’s an example of a bacteria that requires many growth factors

Answer 18

• Leuconostoc mesenteroides requires all 20 amino acids, 4 purines and pyrimidines and 10 different vitamins.

Question 19

what does fastidious mean

Answer 19

need a lot of things required to grow (sometimes called picky eaters)

Question 20

how are the elements H and O added to mediums?

Answer 20

• not found in one specific nutrient
• in H2O and organic media components -food (but don’t need to think about adding)

Question 21

how is phosphorus provided to the medium? why in this way? where is phosphporus limiting?

Answer 21

• Usually provided as phosphate salt (through PO4^3-)
• ex: K2HPO4, KH2PO4
• reason: this is how it’s acquired in the environment
• in freshwater systems PO4^3- is often limiting

Question 22

what is a limiting nutrient

Answer 22

• present in relatively low concentration compared to other nutrients
• when it runs out, growth stops despite other nutrients present.

Question 23

what is the source of inorganic organic N, and atmospheric N2 order them from most to least favorable source of N?

Answer 23

• Organic N
  -provided as N rich organic molecules (ex. Amino acids or short peptides) -does not need to be reduced so most favorable
• Inorganic N
  -salts (like KNO3 or NH4Cl)
  -must be reduced to NH3 -used to make amino acids (-NH2), not as favorable requires energy.
• Atmospheric N2
  -N2 is reduced to 2NH3 -through nitrogen fixation
  -NH3 is used to make amino acids
  -energetically expensive (so least favorable)

Question 24

what is thhe source of inorganic and organic S which is the more favourable source of S?

Answer 24

• Inorganic S
  -provided as salts (ex. MgSO4)
  -Must be reduced to the level of S2- through assimilative sulfate reduction, used to make amino acids.
• Organic S
  -Pre-made amino acids (cyteine and methionine)
  -less energy to assimilate, so organic S is more favorable.

Question 25

organisms are placed into 2 groups based on how they obtain C, what are the groups and their carbon sources?

Answer 25

* Heterotrophs -use organic carbon (one or more C is alr reduced, looks like a C atom with one or more H's) -ex. organic acids, alchohols, carbohydrates, amino acids * Autotrophs -use inorganic carbon (CO2) as sole source of carbon -requires energy to assimilate (turn to organic form) -through photosynthesis ex. anabaena

Question 26

what are the 6 classes of culture media

Answer 26

1. defined medium 2. minimal medium 3. complex medium 4. differential medium 5. selective medium 6. enriched medium

Question 27

what's a defined medium and what's it useful for

Answer 27

* exact chemical composition is known * useful for studying metabolism

Question 28

what's a minimal medium

Answer 28

a defined medium that provides the minimum nutritional requirements for growth (no growth factors just essential macronutrients).

Question 29

what's a complex medium? and examples

Answer 29

* exact chemical composition (chemical formulas) is unknown * often made from meat or yeast extracts * supply variety of growth factors * ex: T-soy broth and plates (lots of growth factors)

Question 30

can you study metabolism with a complex medium

Answer 30

no, we don't know how much of each element we have

Question 31

which culture media is opposite of defined medium

Answer 31

complex medium

Question 32

what's does a differential medium, allow and an example

Answer 32

* allows different bacteria to be distinguished * ex: blood agar: T-soy plate + 5% sheep's blood, allows differentiation of hemolytic bacteria (bacteria with ability to hemolyze or destroy red blood cells)

Question 33

what are the 3 results of differentiation on a blood agar plate? what they mean and what color (differential medium)

Answer 33

* alpha (a) – incomplete destruction of blood cells, (green appearance) * Beta (B) – complete destruction, yellow (t-soy color, cleared red) * gamma (y looking thing) – no destruction (red still, hasn't gone)

Question 34

what's a selective medium and example

Answer 34

* contains ingredients that inhibit the growth of unwanted microbes * allowing only specific microbes to grow * ex: Mannitol salt agar -selective as it contains very high salt, so that only halotolerant (salt-tolerating) bacteria will grow. -used to isolate staphylococci from skin (halotolerant) ## Footnote Mannitol salt agar also has color so also differntial medium, pH indicator changes color when bacteria ferment mannitol to acid.

Question 35

what's an enriched medium and example

Answer 35

* special nutrients are added to a regular medium to encourage growth of fastidious bacteria -bacteria that have complex nutrient requirements. * complex nutrient requirements =require many growth factors * ex: blood agar, chocolate agar -5% sheeps blood cooked so its broken down ## Footnote (some bacteria will only grow if there's blood)

Question 36

what are the 2 groups for the 2 ways microorganisms obtain their **energy** for anabolism?

Answer 36

* chemotroph -obtains energy from chemical reactions (like humans breaking down glucose) * phototroph -obtains energy from sunlight (like plants)

Question 37

what are the 2 groups for the 2 ways microorganisms obtain their **electrons** for anabolism?

Answer 37

* organotroph -electrons come from already reduced organic molecules (like glucose) * lithotroph -electrons come from reduced inorganic molecules (like H2O)

Question 38

what are the 2 groups for the 2 ways microorganisms obtain their **carbon for cell material**?

Answer 38

* Heterotroph -pre-exisiting organic molecules * Autotroph -inorganic CO2

Question 39

where does a chemoorganoheterotroph get its energy, e-, and carbon

Answer 39

* **energy** from chemical reactions * **electrons** from already reduced organic molecules * **carbon** from pre-existing organic carbon sources

Question 40

what organisms are Chemoorganoheterotrophs?

Answer 40

all animals, fungi and protozoa, many bacteria

Question 41

some microbes can consume organic material in the absence of oxygen, what processes allow this?

Answer 41

* fermentation * anaerobic respiration -use something other oxygen as e- acceptor

Question 42

where does a photolithoautotroph get its energy, e-, and carbon?

Answer 42

* energy from sunlight * electrons from an inorganic chemical (like H2O) * carbon from inorganic CO2

Question 43

what organisms are Photolithoautotrophs?

Answer 43

cyanobacteria (and chloroplasts in green plants)

Question 44

how can photolithoautotrophic bacteria carry out photosynthesis without generating O2? what is this process called? what's an example of a bacteria that does this?

Answer 44

* by replacing electron source (instead of H2O, H2S or S0) and turning it into something other than oxygen. * called anoxygenic photosynthesis * ex: purple sulfur bacteria from deep in ocean (anaerobic environment)

Question 46

where does a photoorganoheterotroph get its energy, e-, and carbon?

Answer 46

* energy from sunlight * electrons and carbon from organic material ## Footnote (taking energy from sunlight and also eating something)

Question 47

how do photoorganoheterotrophs assimilate low energy organic acids from waste products of other organisms?

Answer 47

* they use light energy

Question 48

what do photoorganoheterotrophs use light energy from the sun for?

Answer 48

* Use light energy to assimilate low energy organic acids from waste products of other organisms

Question 49

Photoorganoheterotroph example?

Answer 49

purple non-sulfur bacteria ## Footnote (don't use sulfur for electrons, do oxygenic photosynthesis unlike purple sulfur bacteria who are anoxygenic)