How much slower does E coli grow in M9 vs LB? - (Mar/30/2011 )
I'm working on an E coli strain that grew from OD 0.05 to 5 in ~8h. However, when I inoculated a colony of the strain in M9 (no other supplements), I got no growth after 16h! Is this normal for cell growth in M9? I'm switching to M9 because the residual lactose in E coli is giving me leaky expression. Would replacing tryptone with casamino acid in LB help? (I've tried adding 0.5% glucose but need further repression)
-donny-
donny on Wed Mar 30 07:06:24 2011 said:
I'm working on an E coli strain that grew from OD 0.05 to 5 in ~8h. However, when I inoculated a colony of the strain in M9 (no other supplements), I got no growth after 16h! Is this normal for cell growth in M9? I'm switching to M9 because the residual lactose in E coli is giving me leaky expression. Would replacing tryptone with casamino acid in LB help? (I've tried adding 0.5% glucose but need further repression)
Hola, you think that you have lactose in LB because tryptone could have traces of it; but if you add glucose to the LB you could repress in the same way that in minimal medium, because I think one of the problem is de cAMP level, (high in any medium without glucose). Moreover if you use a lacY minus strain or lacIq+ you could repress better. Buena suerte
-protolder-
M9 medium needs a carbon source added, and often strains require thiamine (see the genotype). As was mentioned, glucose would be a good carbon source, to inhibit Lac promoter expression.
-phage434-