Degradation of phthalic acid esters by the microbial consortium isolated from a contaminated soil

Phthalic acid esters are synthetic compounds used as emollients in polymer and plastic compounds. The entry of these compounds into the environment and the human food cycle and the development of a variety of cancers has raised global concerns. The purpose of this research was to investigate the concentration of phthalic acid esters (PAEs) in the soil exposed to the leachate (landfill) and finding a microbial consortium capable of the degradation of these pollutants. The concentration of phthalic acid esters in the soil was measured by the ultrasonic method and GC-MS. The results showed that the concentration of diethyl hexyl phthalate (DEHP) in soil (4.52 mg/Kg) was 6 times that of its international standard (0.7 mg/Kg). Microbial enrichment was performed in a mineral salt medium containing phthalic acid esters (30 o C and 120 rpm) and a microbial consortium capable of degrading phthalic acid esters was isolated. To investigate the biodegradation of phthalic acid esters by consortium, the residual phthalate concentration was extracted with ethyl acetate and measured by GC-MS. The results showed that the this consortium was able to degrade more than 96% of low molecular weight phthalates of dimethyl phthalate, diethyl phthalate and dibutyl phthalate (medium molecular weight phthalate) (30 o C and 120 rpm). In the case of DEHP (the world's most widely used plasticizer), the consortium was able to degrade it by 55% at 400 mg/L. Besides, phthalic acid esters separately were degraded almost completely by this consortium (5 days incubation, 30 oC, 120 rpm). Our results demonstrate the biodegradation of phthalic acid esters by this consortium and recommend its use for bioremediation of phthalates in contaminated soils.