FIG. 9.

Survival of P. putida strains in soil. (A) P. putida KT2440 (○), its rpoS-deficient derivative strain P. putida C1R1 (▵), P. putida KT2440(pWWO) (□), and P. putida C1R1(pWWO) (◊) were introduced in unamended sterile soil in independent jars; (B) symbols as in panel A, but the microcosms were amended with 0.1% (wt/wt) m-methylbenzoate. For each determination, five different dilutions were plated by the drop-plating technique (20-μl drops were laid on selective plates). Mean values are shown, and maximum and minimum values are presented with error bars. Data are from a single experiment, although microcosms were run in duplicate, and typically the same result was observed. Selective medium for P. putida strains bearing the TOL plasmid was 5 mM m-methylbenzoate-supplemented M9; for strains without the TOL plasmid the same medium was supplemented with 5 mM benzoate.