TABLE 2.
Statistical analysis of the experiments performed in this study
| Parameter, condition(s), and/or strain | No. of nematodes tested | TD50 (days)a | P value |
|---|---|---|---|
| Nematode survival | |||
| Killing by W22703 infection | |||
| 15 min | 60 | 9.8 | <0.0001 |
| 1 h | 66 | 9.2 | <0.0001 |
| 4 h | 75 | 10.6 | <0.0001 |
| Permanent culture on OP50 feeding strain | 81 | 15.9 | Standard |
| Effect of tcaA deletion on toxicity | |||
| W22703 | 17 | 8.2 | Standard |
| W22703 ΔtcaA | 65 | 13.4 | <0.0001 |
| W22703 ΔtcaA/pACYC/F37.R43(s) | 85 | 7.1 | 0.13 |
| W22703/pACYC184 | 66 | 6.9 | 0.04 |
| OP50 | 81 | 13.5 | <0.0001 |
| Effect of feeding on heat-killed/sonified bacteriab | |||
| DH5α/pBAD; 37°C + OP50 | 91 | 8.6 | Standard |
| DH5α/pBAD/HisA(tet)-tcaA; 37°C + arabinose + OP50 | 94 | 8.9 | 0.54 |
| DH5α/pBAD/HisA(tet)-tcaA; 37°C + arabinose + OP50 (sonified) | 93 | 9.0 | 0.017 |
| W22703/pBAD/HisA(tet)-tcaA; 37°C + OP50 | 96 | 8.2 | 0.33 |
| W22703/pBAD/HisA(tet)-tcaA; 37°C + arabinose + OP50 | 96 | 9.5 | 0.06 |
| W22703/pBAD/HisA(tet)-tcaA; 15°C + OP50 | 186 | 8.5 | 0.37 |
| W22703/pBAD/HisA(tet)-tcaA; 15°C + arabinose + OP50 | 88 | 8.0 | 0.20 |
| W22703; 15°C + OP50 (sonified) | 86 | 12.5 | <0.0001 |
| W22703 ΔtcaA; 15°C + OP50 (sonified) | 93 | 11.3 | 0.0002 |
| W22703 (live); 15°C + OP50 | 90 | 5.8 | <0.0001 |
| Nematocidal activity of WA314 strains | |||
| WA314/pYV | 94 | 7.4 | Standard |
| WA314/pYVΔyadA | 92 | 8.4 | <0.01 |
| WA314/pYVΔyopE | 93 | 6.8 | 0.08 |
| WA314 Δirp1 | 90 | 7.6 | 0.64 |
| WA314 Δinv | 67 | 8.3 | <0.01 |
a
TD50 values were calculated with the drc package of the R software. The raw data were analyzed using the GraphPad Prism program. P values of <0.01 shown in bold letters are considered significantly different from the survival curve used as the standard.
b
Overnight cultures for experiments with heat-killed (except as noted) bacteria and untreated OP50 cells were incubated at 37°C or 15°C as indicated. If appropriate, the medium contained arabinose. All experiments were performed in triplicates.