FIG. 2.

Acyl-HSL mineralization by untreated and heat-inactivated turf soil. The left and right y axes describe each data point as disintegrations per minute and percent recovery, respectively. Dashed lines represent the theoretical amount of ¹⁴CO₂ that would be released if the initial degradation step was not biological and governed by a rate-limiting, abiotic hydrolysis of the acyl-HSL lactone ring, with subsequent biological mineralization of the resultant acyl-homoserine product (16, 54, 70). (A) Release of ¹⁴CO₂ over the initial 2 h of incubation of a representative soil slurry with oxohexanoyl-l-[1-¹⁴C]HSL at pH 5.5. ⧫, untreated turf soil; ▴, autoclaved turf soil. An influence similar to that of the autoclaved soil on degradation activity was observed when the soil had been γ-irradiated (data not plotted). (B) Mineralization by the same samples over a 34-h incubation period.