Updated project metadata. The experimental project studied a MIDAS adhesin minus mutant of predatory bacterium B. bacteriovorus.The predatory bacterium normally invades and lives inside E.coli bacteria, rounding them up to form a two-bacterial structure, called a bdelloplast, and killing the E.coli from the inside. However the MIDAS mutant predator failed to invade in 10% of cases due to one of its (many) attachment/invasion mechanisms being absent. We enriched and purified the 10% of bdelloplasts which did not have an invaded predator inside, by Percoll gradient centrifugation. Although these bdelloplasts did not have an invaded predator they were still rounded and dead. We sent the bdelloplast sample for total protein content analysis at the Oxford Advanced Proteomics Facility. We found that although the bdelloplasts areE.coli cells they also contain secreted Bdellovibrio proteins that normally an invading wild type Bdellovibrio is known to secrete into their prey, during invasion. This suggests that a short-lived failed attachment allowed the Bdellovibrio to secrete in predatory proteins , even though it failed to enter the E.coli, and that those predatory proteins alone were enough to round and kill it.