Effects of two common antibiotics on the growth and lipid production of Tetradesmus obliquus cultivated in the effluent of municipal wastewater treatment plant

Abstract

Using the effluent of municipal wastewater treatment plant (WWTP) to cultivate lipid-producing microalgae is likely to reduce the production cost of algae-derived biodiesel. However, the toxicity of antibiotics present in the effluent may affect the growth of microalgae and lipid production. This study investigated the effects of erythromycin (ERY) and tetracycline (TC) on the growth and lipid production of Tetradesmus (Scenedesmus) obliquus cultivated in the effluent of municipal WWTP. The results indicated that ERY was more toxic to T. obliquus compared to TC. The critical concentrations of ERY resulting in S. obliquus algae growth inhibition and increased lipid accumulation were 100 and 10 μg L−1, respectively. Maximum lipid accumulation was observed at an ERY concentration of 50 μg L−1, while lipid accumulation was significantly decreased at ERY concentrations greater than 250 μg L−1. Interestingly, the contents of polyunsaturated fatty acids in T. obliquus exposed to ERY were significantly increased, while the contents of total saturated fatty acids and monounsaturated fatty acids were significantly decreased. TC had no effect on the growth or lipid production when the concentration reached 500 μg L−1. Overall, the presence of ERY and TC in the municipal WWTP effluent does not largely affect the growth or lipid production of T. obliquus.