M. smegmatis culture

 

M. smegmatis has a division time of around 3 hours.  Therefore, in 24 hours (8 cycles of cell division), a culture will have 256 cells for every viable cell in the innocula.  This means the culture will be 256 times as turbid as at time 0. 

It should be noted that M. smegmatis is a fast growing mycobacterium, unlike M. tuberculosis (which is cultured in a very similar manner to M. smegmatis) and M. leprae. Therefore, M. smegmatis allows for efficient Mycobacteriophage discovery.

M. smegmatis is a durable, non-hazardous environmental microbe that can be cultured in any laboratory.  The media is resistant to the growth of other microbes, and the culture can be done (with moderate care) outside of sterile hoods.  The Jacobs laboratory will ship the M. smegmatis mc2-155 strain to a school that requests the strain for educational purposes. 

7h9 media is simple to make.  Even though the detergent Tween-80 protects against a substantial amount of contamination since many organisms are inhibited by the presence of this detergent. Take care to exclude Tween-80 in solutions that contain phage, as the detergent inhibits phage adsorption to Mycobacteria.

Liquid culture for agar culture of phage is done in inkwell vials, or any small flat-bottom, sterile container that can stand upright and be gently shaken at 37C.