TABLE 3.
Pherotype groups of 42 riverbank soil isolatesa
| Pherotype group and isolate from which conditioned medium was obtainedb | β-Galactosidase activity in tester strainc:
|
|||||
|---|---|---|---|---|---|---|
| 168 | RS-D-2 | NAF4 | RO-B-2 | RO-H-1 | RO-E-2 | |
| 168 | ||||||
| PS-11 | ++ | +/− | − | − | − | − |
| PS-13 | ++ | +/− | − | − | − | − |
| PS-14 | ++ | +/− | − | − | − | − |
| PS-15 | ++ | − | − | − | − | − |
| PS-18 | ++ | +/− | − | − | − | − |
| PS-30 | ++ | +/− | − | − | − | − |
| PS-51 | ++ | − | − | − | − | − |
| PS-216 | ++ | +/− | − | − | − | − |
| PS-233 | ++ | +/− | − | − | − | − |
| PS-237 | ++ | +/− | − | − | − | − |
| PS-168 | ++ | +/− | − | − | − | − |
| PS-96 | ++ | +/− | − | − | − | − |
| PS-65 | ++ | +/− | − | − | +/− | − |
| PS-68 | ++ | +/− | − | − | − | − |
| RS-D-2/NAF4 | ||||||
| PS-217 | − | ++ | ++ | − | − | − |
| PS-218 | − | ++ | ++ | − | +/− | − |
| PS-64 | − | ++ | ++ | − | − | − |
| PS-194 | − | + | ++ | − | − | − |
| PS-196 | − | + | ++ | − | − | − |
| PS-20 | − | ++ | − | − | − | − |
| PS-24 | − | ++ | − | − | − | − |
| PS-25 | − | ++ | − | − | − | − |
| PS-263 | − | + | − | − | − | − |
| PS-160 | − | + | − | − | − | − |
| RO-B-2/RO-H-1 | ||||||
| PS-52 | − | − | − | ++ | +/− | − |
| PS-53 | − | − | − | ++ | − | − |
| PS-93 | − | +/− | − | ++ | − | +/− |
| PS-95 | − | +/− | − | + | + | − |
| PS-108 | − | + | − | ++ | +/− | − |
| PS-109 | − | + | − | ++ | − | − |
| PS-119 | − | − | − | ++ | − | − |
| PS-130 | − | +/− | − | ++ | +/− | − |
| PS-131 | − | + | − | ++ | − | − |
| PS-31 | − | − | − | ++ | ++ | − |
| PS-55 | − | − | − | + | ++ | − |
| PS-209 | − | +/− | − | ++ | ++ | − |
| PS-210 | − | − | − | ++ | ++ | − |
| PS-261 | − | +/− | − | ++ | ++ | − |
| PS-149 | − | − | − | + | ++ | − |
| RO-E-2 | ||||||
| PS-207 | − | − | − | − | +/− | ++ |
| PS-122 | − | − | − | − | +/− | ++ |
| PS-188 | − | + | − | − | − | ++ |
Specific activation of the QS response indicates a specific pherotype (2) and was measured using tester strains able to detect one of the four previously determined pherotypes through activation of the srfA-lacZ reporter gene. The B. subtilis 168 tester strain was used for detection of the first pherotype, and two tester strains, B. subtilis RS-D-2 and B. subtilis natto NAF4, were used for the second pherotype. The third pherotype was investigated using the tester strains B. mojavensis RO-B-2 and B. mojavensis RO-H-1, and the fourth pherotype was investigated using the B. subtilis RO-E-2 tester strain.
Conditioned media were prepared from riverbank isolates as described previously (53). Isolates indicated by normal type and by boldface were obtained from soil samples 1 and 2, respectively.
Tester strains were inoculated (1:50) into conditioned medium mixed with an equal volume of fresh competence medium. Samples were collected 2 hours after entry into stationary phase and were assayed for β-galactosidase activity as indicated in Materials and Methods. Symbols: ++, strong response, similar to positive control; +, moderate response, approximately 50% of the positive-control response; +/−, weak but reproducible response; −, no activation.