Dimethyl phthalate altered the microbial metabolic pathways in a Mollisol

Dimethyl phthalate (DMP), a member of the phthalate esters (PAEs), is a common contaminant and frequently detected in soil. In this study, metagenomics revealed that DMP contamination in a Mollisol led to alterations in biological genomes and pathways identified using the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The results of functional annotation with pathway information demonstrated that genes involved in metabolism and signal regulatory pathways were changed in soil contaminated with DMP. Genes involved in nitrogen metabolism, carbon metabolism (glycolysis, the citrate cycle and pentose phosphate pathway) and signal regulatory pathways (apoptosis pathway, adipocytokine signalling pathway and glutamatergic synapse signal pathways) were more abundant under DMP contamination in the Mollisol. Quantitative PCR (QPCR) assays also showed that copies of genes associated with DMP degradation, pcmA, pehA, phtAb, phtB and phtC, correlated positively with the concentration of DMP. The results also suggested that the acceleration of nitrogen and carbon metabolism in the Mollisol by DMP contamination arose from altering the signal regulatory pathways. This is one of the most damaging mechanisms for microorganisms; therefore, DMP contamination will adversely affect the ecosystem in the Mollisol.