FSCN 2021 Lecture 5: 13 February -2
24 Feb 2019
School
Department
Course
Professor
● BSL 1 teaching lab
○ E. coli
● BSL 2 research lab
○ Salmonella
● BSL 3 research lab
○ Clostridium botulinum
● BSL 4 research lab
○ Ebola
● Aseptic Technique
○ Hold loop needle at 68 degrees celsius and pass the loop through the flame so as to heat the wire
red hot along the entire length
○ Cool for 10 seconds before use
○ Remove the caps: while wire is cooling, remove the first cap by grasping it with the little finger
● Pure Culture isolation
○ Process of moving bacteria into 3 sections of the petri dish
○ You can get isolated colonies so we know that it is a pure culture
● Culture media
● Minium:
○ carbon source (glucose)
○ Nitrogen source (NH3)
○ Phosphorus, sulphur and potassium
● Complex:
○ Extra amino acid rich ingredients, such as yeast extract, peptone or beef extract
● Culture media can be devised to select for and differentiate between bacteria
○ Selective medium
■ Probiotics have to withstand bile
○ Differential medium
● Excess yeast- vegemite
Microbial Growth
● Increase in number of cells, not cell size
○ Populations
○ Colonies
● The requirements for growth
○ Physical requirements
■ Temperature
● Minimum growth temperature
● Optimum growth temperature
● Maximum growth temperature
● Mesophiles (body temperature)
● Thermophiles (warm-loving)
● Hyperthermopphiles (very hot environments)
● Psychrophiles (very cold loving)
● Psychrotrophic bacteria (cold loving)
○ Grow between 0 and 20-30 degrees C
○ Cause food spoilage
● Food preservation temperatures
○ Danger zone: 60 to 130 degrees F
Document Summary
Hold loop needle at 68 degrees celsius and pass the loop through the flame so as to heat the wire red hot along the entire length. Remove the caps: while wire is cooling, remove the first cap by grasping it with the little finger. Process of moving bacteria into 3 sections of the petri dish. You can get isolated colonies so we know that it is a pure culture. Extra amino acid rich ingredients, such as yeast extract, peptone or beef extract. Culture media can be devised to select for and differentiate between bacteria. Increase in number of cells, not cell size. Grow between 0 and 20-30 degrees c. Danger zone: 60 to 130 degrees f. Temperatures in this range destroy most microbes, although lower temperatures take more time. Rapid growth of bacteria; some may produce toxins. Most bacteria grow between ph 6. 5 and 7. 5. Molds and yeasts grow between ph 5 and 6.
