Fate of di (2-ethylhexyl) phthalate and its impact on soil bacterial community under aerobic and anaerobic conditions

Abstract

In this study, we examined the influence of oxygen on the degradation of di (2-ethylhexyl) phthalate (DEHP), the accumulation of its monoester metabolite mono (2-ethylhexyl) phthalate (MEHP) and their impact on soil bacterial communities. Soil microcosms artificially contaminated with DEHP (0, 100 and 1000 mg kg−1) were incubated under aerobic and anaerobic flooded conditions, and sacrificed after 0, 21 and 42 days. The results indicated that DEHP degradation proceeded at similar rates in aerobic and anaerobic flooded soils, but accumulation of metabolite MEHP was more likely to occur in anaerobic soils. Moreover, MEHP generated from DEHP degradation seemed to be readily released into the water phase, which may arouse health concerns. Illumina Miseq sequencing showed that MEHP had a greater impact on soil bacterial community than DEHP at the same dosage, and a wide range of bacterial phylotypes were inhibited by MEHP under anaerobic conditions. High DEHP contamination (1000 mg kg−1) significantly reduced bacterial diversity and altered bacterial community structure under anaerobic conditions, but not under aerobic conditions. Firmicutes was constantly inhibited by DEHP under both aerobic (Bacillus) and anaerobic (unclassified Clostridiales Family_XVIII) conditions. On the other hand, bacterial phylotypes belonging to Actinobacteria, β-Proteobacteria and Gemmatimonadaceae were constantly enriched by DEHP in anaerobic soils, however no such a clear pattern existed in aerobic soils. This work greatly expanded our understanding of the fate of DEHP and its modifying effect on bacterial communities under different environmental conditions.