Effect of dibutyl phthalate on microalgal growth kinetics, nutrients removal, and stress enzyme activities

The dibutyl phthalate (DPB) is an emerging plasticizer contaminant that disrupts the biological processes of primary producers, especially phytoplankton. In this study, two microalgal species (Chlorella sp. GEEL-08 and Tetradesmus dimorphus GEEL-04) were exposed to various concentrations of DBP extending from 0 to 100 mg/L. The growth kinetics, N-nitrate, and P-phosphate removal efficiency were assessed. The response enzymes such as malonaldehyde (MDA) and superoxide dismutase (SOD) were also investigated. The results revealed that the Chlorella sp. GEEL-08 at 10 mg/L concentration of DBP exhibited higher growth (0.88 OD_680nm) compared to T. dimorphus GEEL-04 (0.80 OD_680nm). More than 94% of N and P were removed from culture media by both microalgal species. The DBP (>50 mg/L) significantly exacerbates the growth of both microalgae species and the growth inhibition ratio was in the range of 3.6%-25.9%. The SOD activity and MDA were higher in T. dimorphus culture media than in the culture media of Chlorella sp. The results reflect the hazard and the risk of plasticizers on primary producers in the ecosystem.