Ethylene Biosynthesis in Soil: II. Kinetics and Thermodynamics in the Conversion of 1‐aminocyclopropane‐1‐carboxylic Acid to Ethylene

Abstract

Abstract Kinetic analyses were performed to characterize the conversion of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) to ethylene (C 2 H 4 ) in soils. Application of three linear transformations of the Michaelis‐Menten equation indicated that the K m values varied slightly among soils, but were similar in magnitude. By using the Lineweaver‐Burk plot, the K m values in three soils ranged from 2.7 to 6.1 (avg = 4.8) m M and V max values ranged from 3.9 to 16.5 mmol of C 2 H 4 released kg −1 soil 48 h −1 . The activation energy ( E a ) and enthalpy of activation (Δ H *) values, expressed in kJ mol −1 , ranged from 35.4 to 70.5 (avg = 49.4) and 32.8 to 67.9 (avg = 46.8), respectively. The Q 10 values within a temperature range of 5 to 50°C ranged from 1.52 to 2.60. A direct relationship was established between soil pH of 20 unbuffered surface soils and ACC enhanced‐C 2 H 4 production, but no such relationship was found with any other soil parameter tested including organic C, total N, CEC, and texture. Antibiotic treatments of soils revealed that both fungistatic and bacteriostatic agents were effective in inhibiting (25–82%) ACC derived‐C 2 H 4 production in soils indicating that both major groups are active C 2 H 4 producers.