The IJ yield after growth on P. luminescens. The different bacterial strains were inoculated onto lipid agar plates, incubated for 3-4 days at 30°C and 40 surface-sterilised H. bacteriophora IJs were added to the biomass. The plates were incubated for 21 days at 25°C and the IJ yields were determined (i.e. total number of IJs/50). For each experiment 5 plates were analyzed for each strain and the experiment was repeated 3 times. Therefore the data shown is the mean ± standard deviation of n = 15 plates for each strain. Statistical significance was determined using a T-test and IJ yields significantly different (P < 0.01) to those obtained using TT01 are indicated with an asterisk.