M9 medium

Introduction

M9 media is a minimal media used for bacterial cultures. It has the advantage of being cheap and has a very low autofluorescence. M9 media can be supplemented to produce higher growth rates.

Specific Protocols

• M9 minimal media
• M9 supplmented media

• M9 supplemented media

M9 medium also exists in various flavors:

M9-glu contains glucose: In the basic recipe take 800 ml sterile water and supplement with 100 ml 20% (w:v) sterile filtered glucose before adding M9 salts, magnesium and calcium salts.

M9-CA contains casamino acids: In the basic recipe take 800 ml sterile water and supplement with 100 ml 10% (w:v) autoclaved casamino acids (in water) before adding M9 salts, magnesium and calcium salts.

M9-CAglu contains both: In the basic recipe take 700 ml sterile water and supplement with 100 ml 20% glucose and 100 ml casamino acids before adding M9 salts, magnesium and calcium salts.

Warning: salts that are added last often tend to precipitate. I didn't bother about it too much as obviously it didn't influence bacterial growth. There might be a way to avoid precipitation (eventually adding magnesium and calcium first) but I didn't investigate this in detail.