Attachment to abiotic surface by P. luminescens. Photorhabdus strains (as indicated) were grown overnight at 30°C in LB broth (+ Km). The OD600 of the culture was adjusted to 0.05 and 200 μl was added to the well of a 96-well Costar® PP microtitre plate. The plates were incubated for 72 h at 30°C before staining with crystal violet to quantify bacterial attachment. Relative biofilm formation was determined by calculating the OD595 (mutant):OD595 (TT01gfp) ratio and the results shown are the mean ± SD of 3 experiments.