Is there a cheaper alternative to IPTG?

Roland J Saldanha rsaldanh at
Tue Dec 6 19:50:35 EST 1994

In article <Pine.SUN.3.90.941206162348.23020A-100000 at condor>,
> I am trying to induce moderate quantities (about 5 liter cultures) of an
>E. coli strain with a plasmid containing a gene controled by the lac
>promotor. I dont want to finish our next year supply of IPTG and I would
>like to ask if anyone knows about a cheaper alternative of lac induction.
>The E. coli starin is DH5 alpha. Thanks very much from a warm Mexican
>graduate student.   Manuel Carrera, jpaniagf at

I regularly use Lactose! for strains that  are lac plus (DH5 alpha will not be
since it is designed for alpha complementation and your insert presumbaly
inactivates the alpha fragment of lacZ if you are using common vectors).  You
could move your construct to any lac plus strain and do the same.

Lactose is about $5 for a pound and we use 0.2% to induce (10 mls of a 20%
solution / liter).

I use BL21 a strain designed for T7 based constructs.

Roland Saldanha

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