Bacterial Growth -Chapter 3

Question 1

Doubling time/growth rate + understand under different conditions (nutrient metabolism )

Answer 1

• bacterial growth will depended on ideal conditions

- stable environment= K-selection vs. unstable envi.=r-selection (leads to adaptive change)

Question 2

Compare and contrast the growth in pure cultures with growth in the environments

Answer 2

dependent on physical and chemical properties:

1. limited nutrients status
2. microoganisms present, nutrient competition
3. predation

Question 3

Growth curve and the parts of the curve under both the lab and environement

Answer 3

• Lag
• exponential : rate of icnrease proportional to thee number of cellls, low initial cell number= initial growth rate
• stationary phase
• death phase

Question 4

Batch vs. Continuous cultures (how to generate primary or secondary metabolites)

Answer 4

ie. plate vs. add nutrients/remove waste
-low [substrate ]= batch
vs.
-optimal growth
-control flow, [substrate]. pH, temp, O2 levels, ect.
-removes effluent (contains cells, metabolites, waste, unused nutrient)
-controls growth rate (dilution rate/inflow, influent substrate) : control 1 met (high flow), 2 met (low flow)

Question 5

Different types of bacteria with respect to growth rate

Answer 5

• oligotrophs (K strategist, prefer low [sub ], low+consistent response, slow metabolism/cell maintenance)
• copiotrophs ( r strategist, prefer high [sub], rapid response, fast metabolism/exponential growth or dormant stat)

Question 6

At least two electron acceptors can be used under anaerobic condition in place of oxygen

Answer 6

sulfate/So4^-2
nitrate/No3^-1
Sulfur /S

Question 7

Aerobic or anaerobic metabolism yields more energy + why?

Answer 7

Aerobic yields more + uses C for cells mass orCO2 only

• in anerobic /fermentation they use dif e- acceptor–> will use the highest electron affinity first, (final step) when e- acceptors DEPLETED= methanogenesis
• Anaerobic –> disproportionation ( some C –> Co2=Ei acceptors and others CH4

Question 8

Mass balance equation for aerobic and anerobic metabolism

Answer 8

-anerobic resp =LESS efficient, requires alternative e-

Question 9

Taxonomic units

Answer 9

a population, or group of populations of organisms which are usually inferred to be phylogenetically related and which have characters in common which differentiate the unit (e.g. a genus, a family, an order) from other such units (Woese)

Question 10

Cell yield coefficient (y)

Answer 10

the unit amount of cell mass produced per unit amount of substrate consumed

Question 11

What’s happening during the stationary phase?

Answer 11

• growth=death
• bac deal w/ competition
• growth is balanced

Question 12

Why do we use the terms substrate and nutrient?

Answer 12

substrate= E or  carbon source, metabolisms ie. oil 
nutrient= required for growth and repair ie. Nitrogen

Question 13

Why do we use the terms substrate and nutrient?

Answer 13

substrate= E or  carbon source, metabolisms ie. oil 
nutrient= required for growth and repair ie. Nitrogen

Question 14

Give an example of efficiency of degradation of a substrate and how we use this?

Answer 14

-increase effiency= increase yield coefficient

Question 15

Oligotrophy

Answer 15

poor nutrient

growth rate stays constant

Question 16

What would the addition of substrate to their environments result in for r and K strategists?

Answer 16

r= increased growth

k=no growth

Question 17

Why are you more likely to find dormant copiotrophic organisms?

Answer 17

they dont control consumption therefore use of nutrients up ==> dormant

Question 18

Why would oligotrophs be difficult to culture in the laboratory?

Answer 18

• long time needed and often becomes contaminated

- need to know particular nutrient needs

Question 19

How might we be able to study oligotrophic growth?

Answer 19

• use chemoreactor

- acteria rely on the metabolites from another bac ( SYMTROPHY)

Question 20

Why do we need to be careful when attempting to culture and identify soil microorganisms in a lab?

Answer 20

• symtrophy

- ongoing flu of bacterial population in the env. which can alter the growth of other present bacd

Question 21

In a pharmaceutical setting, especially in the production of injectables, it is critical to verify that there are no microorganisms present, how would you show whether there are microorganisms present? (Can you be certain that certain microorganisms don’t exist?)

Answer 21

• VBDC

- 16 s sequencing (help o id

Question 22

In a pharmaceutical setting, especially in the production of injectables, it is critical to verify that there are no microorganisms present, how would you show whether there are microorganisms present? (Can you be certain that certain microorganisms don’t exist?)

Answer 22

• VBDC
• 16 s sequencing (help to identify)
• look for metabolites or toxins/endotoxins

Question 23

What might occur to remedy the situation where the correct microbe is not present in the environment?

Answer 23

microbes adapts to fit environment

Question 24

What may happen to the oligotrophic population when substrate is added?

Answer 24

copiotrophic pop may become overwhelming and or use up nutrients or O2

Question 25

What do values for Y indicate about compounds as substrates for bacterial growth?

Answer 25

the cells must contain catabolic pathways to utilize a specific substrate for growth

Question 26

What do values for Y indicate about compounds as substrates for bacterial growth?

Answer 26

the cells must contain catabolic pathways to utilize a specific substrate for growth

Question 27

How can you change the growth rate under ideal nonlimiting conditions?

Answer 27

change temps

• if you want to change growth rate= change microbe or substrate

Question 28

Describe the process a facultative microorganisms would use to metabolize a substrate?

Answer 28

• they rely on fermentation and in turn methanogensis.

- they utitlize C to create cell mass and also disproportionanation ( Co2 and CH4)

Question 29

What does redox potential mean?

Answer 29

the measure of the tendencies of a chemical species to acquire e- and in turn be reduced

Question 30

What is a redox pair?

Answer 30

e- donor (Cu+) and e- acceptor (Cu2+)

Question 31

How do we measure energy produced during metabolism?

Answer 31

• calculate the delta Eo` ( free energy)

- quantify the products produced

Question 32

Which type of substrate is likely to give most energy, a highly oxidized or a highly reduced substrate?

Answer 32

*transfer of e-

highly reduced

Question 33

How is nitrate reductase expression regulated?

Answer 33

kept within a balance,

- relative rates of synthesis and activation or degredation and inactivation

Question 34

Why is regulation by nitrate important?

Answer 34

nitrate reducate is important in the assimilation of exogenous nitrogen –> fixed nitrogen

Question 35

Where might you find expression of nitrate reductase?

Answer 35

• in plants and in other nitrogen fixating bac

Question 36

Critical dilution rate

Answer 36

• amount of diltuion (amount of nutrient/substrate in solution) being introduced so that the GROWTH RATE =0
• leads to washout