Experiments

CULTURING 'WILD' S. CEREVISIAE

Introduction

Over time, beer makers have evolved many different strains of yeast that ferment sugars into a wide variety of beers (and wines!) with a multitude of different properties. We decided to use these some of these strains as the starting point for our own syn-bio beer making adventures. In thi experiment, yeast strains derived from unfiltered bottled beer as well as strain purchased from home brew equipment suppliers were grown on YEPD agar plates for use in all subsequent experiments.

Materials and methods

Yeast sediment from the bottom of an unfiltered bottle of beer was plated onto a YEPD agar plate using a sterile innoculum loop. Approximately 0.25g of dried yeast purchased from a home brew supplier was diluted in 1.5ml distilled water and plateed using a sterile innoculum loop. Plates were left to grow at room temperature for 2-3 days until visible colonies began to appear. Colonies were grown overnight at 30OC in YEPD media to verifythat media had been prepared correctly.

Results

After a 3 day incubation period a number of colonies suitable for overnight culture are visible on all plates.

Discussion

The purpose of this experiment was to develop our understanding of techniques used to culture yeast strains. Having successfully grown 6 strains of yeast from various sources we now have the beginnings of a library of brewing strains that we can genetically modify in a effort to alter the properties of the beer produced during fermentation. Additionally, the use of readily available yeast strains as a chassis organism for synthetic biology work provides a cheaper and safer alternative than existing bacterial species,particularly amongst members of the DIY-bio community.