TABLE 5.

β-Galactosidase levels expressed in Pseudomonas sp. strain 61-3 harboring pJZBB85R or pJZBB73

Plasmid (relevant markers)	β-Galactosidase activity (U/mg of protein)a
	NR mediumb (1st stage)		MT mediumc (2nd stage)
	12 h	18 h	4 h
pJRD215 (none)	6	NDd	ND
pJZBB85R (phbRPsphb promoter lacZYA)	46	64	123
pJZBB73 (phb promoter lacZYA)	5	5	23

^aOne unit corresponds to the formation of 1 nmol of ONP per min at 28°C. The activity was assayed in duplicate. 

^bCells were cultivated in NR medium at 30°C. 

^cCells grown in NR medium at 30°C for 18 h were transferred to MT medium and subsequently incubated at 30°C for 4 h. 

^dND, not determined.