Cultivating bacteria

Question 1

What is a chemostat?

Answer 1

This avoids the risk of entering the death phase. Fresh media (nutrients) and air pressure is pumped in, and toxins are pumped out - all at a constant rate. The mix is aggravated to avoid bacteria falling to the bottom and not getting access to nutrients.

Question 2

What are the 2 types of media?

Answer 2

Chemically defined - we provide bacteria with what we want to to see how it adapts and survives in those specific conditions.
Undefined ‘complex’ - giving the bacteria everything it needs to thrive

Question 3

Why do we use agar to cultivate bacteria?

Answer 3

Agar is not ‘used’ by the bacteria, thus remaining in the same condition. No nutrients or moisture can be taken from agar so it wont dry out.

Question 4

What is population density and population number?

Answer 4

Density - concentration of bacterial cells
Number - the amount of bacteria in a sample

Question 5

What is generation time and its importance?

Answer 5

= time/ number of generations
It shows how different bacteria can grow in the same conditions; or the same bacteria grown in different conditions. It can also show whether data is statistically significant or not.

Question 6

What are factors that influence bacterial growth?

Answer 6

• temperature
• pH
• O2 availability (aerobic bacteria)
• salinity (the ionic environment)

Question 7

How does temperature affect bacterial growth?

Answer 7

In the body, gut bacteria work best at 37.5, but body bacteria can operate from 10-48, it may survive but not grow.
Psychrophile - 4 (polaromonas vaculolata)
Mesophile - 3 (E. coli)
Thermophile - 60 (geobacillus stearothermophilus)
Hyperthermophile - 88 (thermococcus celer and even higher is pyrolobus fumarii)

Question 8

How does pH affect bacterial growth?

Answer 8

Bacteria in the body thrive at a pH of 7, most bacteria have an internal pH of 7, and its about balance with external pH to survive. pH 7 bacteria are called neutrophiles.

Question 9

How does salinity affect bacterial growth?

Answer 9

Salinity affects the osmolarity of the cell. Most bacteria that aren’t protected against high or low salinity will bring on or draw out water.

Question 10

What is a chemostat?

Answer 10

This is a method of bacterial growth that avoids the stationary phase. Fresh media (nutrients) is pumped in alongside constant air pressure; waste such as toxins is pumped out - this happens at a steady rate. The solution is constantly aggravated to stop bacteria falling to the bottom and not having access to nutrients.
Microfluidics is the same process but on a microscopic level.