Toluene mineralization and growth potential of Pseudomonas putida PaW164 under toluene-limiting conditions

Toluene-induced cells of Pseudomonas putida PaW164 (pWWO-164) were monitore d for growth potential, maintaining the TOL plasmid, and potential toluene mineralization activity in toluene-amended and nonamended soil. A follow-up study was done in a carbon-free mineral salts solution to obtain further i nformation on physiological changes that occur during starvation. These stu dies showed that there was a larger decline in colony forming units (CFUs) recovered on a toluate- or benzoate-defined mineral salts medium than on a complex agar medium, a greater percent decrease of CFU than of potential mi neralization activity, no decrease in direct counts, and no loss of the TOL plasmid during starvation. Toluene-induced cells also showed an increasing lag time and a decreasing potential for mineralization of C-14-toluene wit h starvation. In contrast, the lag time for mineralization of glucose was l ongest at the onset of starvation and reached a minimum by 3 days; thereaft er, the potential for glucose mineralization remained high.