TABLE 1.

β-Galactosidase specific activities in the JM109 host strain in liquid M9 glucose minimal cultures

Plasmids	Sp act (Miller units) with:
	No added l-methionine	100 μg of l-methionine/ml
pRS415, pBAD33	19.3	19.0
pROMET1, pBAD33	26,643	8,476
pROMET1, pMJ33	13,332	2,145