TABLE 1.
Bacterial strains and plasmids used in this work
| Strain or plasmid | Genotype or phenotypea | Reference |
|---|---|---|
| E. coli S17-1 | pro thi hsdR recA Tra+ IncP | 33 |
| A. brasilense | ||
| Sp7 | Wild type | 35 |
| Sp7-S | Spontaneous mutant of Sp7; CR− Floc− | 18 |
| Sp245 | Wild type | 3 |
| Sp7-PM23 | Spontaneous mutant of Sp7; CR+ Floc+ Swarm− | This work |
| Sp7-PM35 | Spontaneous mutant of Sp7; CR± Floc− Swarm+ | This work |
| Sp245-M4, -M5, -M6 | Spontaneous mutants of Sp245; CR− Floc− Swarm+ | This work |
| Sp72001, -4 | Tn5-induced flcA mutants of Sp7; Kmr CR− Floc− | 27 |
| Plasmids | ||
| pAB1220-9c | Derivative of pVK100b containing the flcA gene on a 9-kb HindIII fragment; Tcr | 18 |
| pAB2051c | pLA29.17 derivativeb containing flcA on a 1.1-kb PstI fragment constitutively expressed; Tcr | 27 |
| pAB2053c | pLA29.17 derivative containing flcA on a 4.6-kb BamHI-BglII fragment; Tcr | 27 |
| pSP7115d | Plasmid that restored swarming in strain Sp7-S; isolated from a gene bank of A. brasilense Sp7; Tcr | 27 |
| pAB2053Z | lacZ cartridge cloned into pAB2053; Tcr Kmrlac+ | 27 |
| pLA-lacZ | pLA29.17 derivativeb; lacZ constitutive fusion; Tcr Kmr Lac+ | 1 |
| pAB358 | pVK100 derivative; nifH-lacZ fusion; Tcr | 22 |
a
Ampr, Cmr, Kmr, and Tcr indicate resistance to ampicillin, chloramphenicol, kanamycin, and tetracycline, respectively; CR, Congo red binding; Floc, flocculation; Swarm, swarming ability; lac, lacZ.
b
pVK100 and pLA29.17 are low-copy-number, broad-host-range cloning-vector derivatives of RK2 that are stable in Azospirillum strains.
c
In pAB2051, a truncate form of flcA is cloned under a constitutive promoter, while in pAB2053 and pAB1220-9, flcA is cloned under its own promoter.
d
Isolated by C. Elmerich at the Institute Pasteur, Paris, France.