Culturing From a Single Cell

A presentation on culturing yeast given by Phill Turner at the November, 2020 LAB meeting.

Transcript

1. Culturing From a Single Cell 
 ‘One man and his yeast’ 
 by Phill Turner 1
2. What is it? • Or selecting several groups which gives diversity in case of mutation to use for fermentation 2 • Growing yeast cells on a agar plate, which multiply from a single cell, and taking one group to use for fermentation
3. From one cell to billions 3
4. Reasons for doing it? o Originally there were not many yeasts available o Potential infections in bottled beers o Keeping your own house yeast that has adapted to your brewing system o Personal enjoyment, if you are just a bit of an nerd or anorak like me o To obtain yeast that isn't available elsewhere 4
5. Basic Equipment Needed ❑ Pressure cooker or autoclave ❑ Bunsen burner or camping stove ❑ Loops, various types ❑ Various sized glass containers that can be autoclaved ❑ Malt extract or wort ❑ Petri dishes or plates (plastic or glass) 5
6. Reasons for sterilising 
 in a pressure cooker • If you boil, you will kill the bacteria but you will not kill the spores • They need to go to a higher temperature of 1210C for 10-15 minutes or 1340C for 3 minutes • Dry heat at 1600 for 2 hours • Tyndallisation 6
7. Sterilising 
 1210C for 15 minutes Pressure Cooker Autoclave 7
8. Flame Source Safe working area A camping stove is sufficient 8 Figure 6.1: The updraft of a Bunsen burner creates a dean work area.
9. Loops • disposable one from £2.50 a pack of 10 • Reusable, various prices 9
10. Glassware 10
12. Making plates Agar melts at 950C Solidifies at 450C 12
13. Choosing Your Yeast • Yeast is a single cell fungus • Beer, wine and bread yeast are all closely related • Yeasts adapt to their environment • What characteristics are you looking for? • Are you choosing a yeast to brew a certain style? 13
14. 
 • Inoculate a small vial of wort with yeast • Once it is fermenting, plate onto the Petri dish • Either directly or by diluting the wort first 14
15. Plating out 15
16. The Growing Yeast 16
17. Undiluted and diluted wort 17
18. Choosing your colony(ies) 18
19. Sterilising the loop 19
20. Cooling the loop 20
21. Selecting a colony 21
22. Flaming the vial 22
23. Transfer to the starter 23
24. Flame the vial again 24
25. Replace the cap 25
26. 4 days 26
27. 12 hours later 27