Temporal microbial succession drives phase-dependent kinetics of di(2-ethylhexyl) phthalate biodegradation in soil

Di(2-ethylhexyl) phthalate (DEHP), one of the most important plasticizers, is considered a typical endocrine disruptor. Soil contains high levels of DEHP, and acts as the main medium for its migration into food chain, presenting potential risks to human health. Although soil indigenous microbial communities hold a great potential to degrade DEHP, the kinetics and mechanism of microbial biodegradation for soil DEHP on the long-time scale remain unclear. Here, we analyzed microbial communities from time-series (up to 90 days) samples of laboratory microcosms by sequencing of 16S and ITS rRNA gene amplicons. We found that the kinetics processes of DEHP biodegradation were well fitted by a biphasic model with two independent kinetic phases: phase I as a first-order kinetics process (0–10 days, r 2 = 0.975), and phase II as a fractional power kinetics process (11–90 days, r 2 = 0.967). Linear discriminant and partial least square regression analyses showed that bacterial genera Clostridium , Sporotomaculum , Mycoplana , and Hyphomicrobium were involved in DEHP biodegradation during phase I, and genera Bacillus and Nannocystis were responsible for DEHP biodegradation during phase II. Moreover, we observed transition in microbial co-occurrence patterns: closer inter-taxa connections between bacterial degrader and fungal genera Aspergillus , Fusarium , and Pleurotus in phase I. Such divergence in the composition of potential DEHP-degrading bacteria and their interactions with fungi may induce the decreased degradation rates from phase I to phase II. This study systematically deciphers the bacterially driven DEHP biodegradation kinetics, and provides fundamental basis for developing strategies for efficient DEHP removal in soil.