Dimethyl phthalate damaged the cell membrane of Escherichia coli K12.

Dimethyl phthalate (DMP), a phthalate ester (PAE), is a ubiquitous and organic pollutant. In this study, the toxicity of DMP to Escherichia coli K12 and its underlying mechanism were investigated. The results showed that DMP inhibited the growth of E. coli K12 and induced cell inactivation and/or death. DMP caused serious damage to the cell membrane of E. coli K12, and the damage increased with higher DMP concentrations. DMP exposure disrupted cell membranes, as evidenced by dose-dependent variations of cell structures, surface properties, and membrane compositions. Increases in the malondialdehyde (MDA) content indicated an increase in oxidative stress induced by DMP in E. coli K12. The activity of succinic dehydrogenase (SDH) was changed by DMP, which could affect energy metabolism in the membrane of E. coli K12. The expression levels of OmpA and OmpX were increased, and the expression levels of OmpF and OmpW were decreased, in E. coli K12 exposed to DMP. The toxicities of DMP to E. coli K12 could be ascribed to membrane disruption and oxidative stress-induced cell inactivation and/or death. The outcomes will shed new light on the assessment of the ecological effects of DMP.