TABLE 2.
Expression of a plasmid-borne pstS::gusA gene fusion in S. meliloti strains carrying pstC1021 or pstC wild-type alleles following growth in minimal medium with limiting and excess Pi
| Strain (properties) | β-Glucuronidase activity (Miller units)a
|
|
|---|---|---|
| P0 medium | P2 medium | |
| RCR2011 (empty vector) | 40 ± 16 | 41 ± 22 |
| RCR2011 (pstC+, pTH1736) | 1,286 ± 59 | 69 ± 21 |
| Rm1021 (pstC1021, pTH1736) | 1,000 ± 64 | 1,076 ± 83 |
| RmP110 (Rm1021, pstC+, pTH1736) | 1,208 ± 70 | 73 ± 28 |
| RmH615 (Rm1021, phoB, pTH1736) | 53 ± 30 | 118 ± 16 |
a
The pstS::gusA fusion plasmid was pTH1736. The β-glucuronidase activity of S. meliloti cells grown in phosphate-free MOPS minimal medium (P0 medium) or MOPS minimal medium containing 2 mM phosphate (P2 medium) was measured as described in Materials and Methods. RCR2011 carrying the empty reporter plasmid pTH1582 was used as a background control. The data are averages ± standard errors for triplicate determinations.