Fig 5.
Endogenous competence development in CDM. (A) Development of competence, expression from PsigX, and pheromone secretion by strain MW30 (PsigX-luxAB) during growth in CDM in parallel closed culture tubes. The tubes were opened on reaching the indicated OD550 values, and their contents were distributed for three assays. MW07 donor DNA (0.5 μg) was added to one 500-μl sample from each culture; after 15 min at 37°C, DNase was added and dilutions were plated for Cmr transformants after 60 min of further incubation. Triplicate 150-μl samples from each tube were exposed to decanal vapor in a 96-well plate for 2 min before determining luminescence. A 4-ml filtrate of the remainder (0.2-μm filters) was prepared for determination of XIP as comS-complementing activity (ComS11-17 equivalents) by bioassay, as described in Materials and Methods. (B) Growth kinetics of cultures assayed for panel A.