FIG. 1.

Isotope shifts during degradation of toluene and a toluene-toluene-d₈ mixture by P. putida strain mt-2. The decrease in toluene (▪) and concomitant increase in ¹³C (R = ¹³C/¹²C) in the remaining substrate (□) and the decrease in toluene-toluene-d₈ concentration (▴) and concomitant increase in deuterium R_t = [toluene-d₈]/[toluene] in the residual nondegraded substrate fraction (▵) were monitored over time. In every case, data are shown for one representative experiment out of three performed.