Biodegradation and kinetic analysis of phthalates by an Arthrobacter strain isolated from constructed wetland soil

A bacterial strain C21 isolated from constructed wetland soil was identified as Arthrobacter sp. based on 16S rRNA gene sequence analysis and physio-biochemical characteristics and was capable of utilizing di-n-butyl phthalate (DBP) as a carbon and energy source for growth. Strain C21 can also utilize other phthalates (PAEs) up to a molecular weight of 390.56 and phthalic acid (PA). The biodegradability of these compounds decreased with the increase in the length of phthalate alkyl chains and molecular weight. Kinetic analysis indicated that the strain C21 cell growth on DBP fitted well with Haldane-Andrews’ model (R ²?>?0.98) with μ _max, K _s, and K _i of 0.12/h, 4.2 mg/L, and 204.6 mg/L, respectively. When the initial DBP concentration was lower than 100 mg/L, DBP biodegradation reaction fitted with the first-order kinetics. The results suggested that Arthrobacter strain C21 played an active role in the bioremediation of the wetland contaminated with phthalates.