Fig 4.

A LysR-family regulatory protein known to be responsible for the regulation of 2-FA metabolic genes regulates the inducible chemotactic response to 2-FA. P. putida strains Fu1, PSF2 (psfB::Km-inactivated strain), and PSF2 pPSF210 (psfB-complementing strain) were grown on 10 mM pyruvate (PYR) and 5.0 mM 2-FA to provide inducing conditions and assessed by the plug assay (see the legend to Fig. 2 for a detailed assay description). Attractants are listed to the left of each row. Descriptions of the psfB mutant PSF2 and the complementing plasmid pPSF210, which carries psfB in trans, can be found in reference 23. Images were documented after 10 min by photography using backlighting. Images shown are representative of assays conducted in triplicate. White arrows indicate positive chemotaxis responses.