how we cultivate bacteria L4

Question 1

what do bacteria need to grow

Answer 1

gases, moisture, nutrients, temperature, ph, correct ionic balance (salt)

Question 2

how do bacteria produce and consume energy to allow growth

Answer 2

utilisation of metabolic reactions
Catabolic - energy releasing reactions
Anabolic - building energy into food
To achieve this bacteria need nutrients

Question 3

what are the two types of nutrients

Answer 3

macronutrients and micronutrients

Question 4

what are the 4 macronutrients and what do they provide

Answer 4

carbohydrates, proteins, lipids, nucleic acids
provide the elements needed for growth when they are broken down

Question 5

what elements do bacteria need to grow and what are they used in

Answer 5

carbon- 50%: sugars and amino acids
oxygen- 17%: H20 or O2
nitrogen- 13%: DNA, amino acids
phosphorus- 2.5%: DNA

Question 6

nutrients provided through liquid or solid broth called media
describe the two types of media

Answer 6

1. chemically defined media
   - control concentrations of each element precisely
   - remove or add elements to see how it effects growth
2. undefined complex media
   - has everything needed for bacteria to grow

Question 7

what does undefined complex media contain

Answer 7

tryptone, yeast extract, NaCl

Question 8

how can you measure bacterial growth

Answer 8

1. population density
2. population number

Question 9

what can you calculate from analysing population number and population density

Answer 9

1. growth rate
2. generation time

Question 10

what are 2 ways you can measure bacterial growth

Answer 10

1. spectrophotometer: measures population density
   - includes dead or debris so less sensitive
   to be more sensitive, measure population number
2. colony forming units: measures population number
   - may underestimate for cells in chains or clusters
   - slow

Question 11

exponential growth graph can be turned to linear log graph
what is the equation to work out final cell number after growth of a culture

Answer 11

N = N02to the power of n
N: final cell number
N0: initial cell number
n: number of generations

Question 12

what is the equation for generation time

Answer 12

g = t/n
g: generation time
t: duration of exponential growth
n: number of generations

Question 13

why is knowing generation time useful

Answer 13

Compare different bacterial species growing in the same condition
Compare one species grown in different conditions

Can also be used to show your data is statistically significant (or not

Question 14

what environmental factors influence bacterial growth

Answer 14

temp, ph, oxygen availability, salinity

Question 15

what are extremophiles

Answer 15

bacteria that can grow under harsh conditions that would kill other bacteria

Question 16

The temperature ranges that bacterial species grow at varies considerably
what is the temperature ranges for mesophiles

Answer 16

min: 10 degress
optimum: 39
max: 46
when above optimum, proteins denature causing growth to reduce steeply

Question 17

bacteria grow in a range but possess an optimum
Optimum pH is based on extracellular environment only
as Ph of batch changes often, what is needed

Answer 17

buffer in the media
Na2HPO4 and KH2PO4 are excellent buffers

Question 18

what is optimum ph for E.coli

Answer 18

7
- water

Question 19

how does Salinity effect growth

Answer 19

nonhalophile (e.coli): hate salt
halotolerant: can survive in low salt concentrations
halophile: can survive in low salt concentrations
extreme halophile: survive in high salt concentrartions

Question 20

how does oxygen effect growth

Answer 20

aerobic need oxygen to grow, other do not

Question 21

what is chemostats

Answer 21

this is a continous culture
fresh media is added and waste is removed
Once equilibrium is obtained: volume, population density, growth rate and metabolic state remain constant
bacteria growth is in steady state
All culture parameters remain constant
motor keeps bacteria agitated

Question 22

how is dilution rate and growth rate (µ) related

Answer 22

dilution rate should be equal to growth rate
- bacteria that is washed out is same that is washed in

Question 23

how is dilution rate worked out

Answer 23

dilution rate= flow rate/volume

Question 24

What would happen if the Flow Rate (F) exceeded Growth Rate

Answer 24

too many nutrients and bacteria would not be able to grow fast enough
- should wash out bacteria

Question 25

what would happen if the flow rate is below growth rate

Answer 25

not enough nutrients so bacteria may struggle to grow
- enter stationary phase

Question 26

what is MICROFLUIDICS

Answer 26

An emerging technology aiding the understanding of bacterial physiology
Build an agar pad with tracks to hold cells in some form of order instead of looking at messy division under microscope
Bacteria grows along the ridges