Salicylate biodegradation by various algal-bacterial consortia under photosynthetic oxygenation

Abstract

Four green microalgae (Chlorella sorokiniana, Chlorella vulgaris, Scenedesmus obliquus and Selenastrum capricornutum), a wild Bolivian microalga strain and two cyanobacteria (Anabaena catenula and Microcystis aeruginosa) were compared for tolerance to salicylate, O₂ production capacity and ability to support salicylate degradation by a Ralstonia basilensisstrain in symbiotic microcosms with the microalgae. Microcystis aeruginosa had the highest tolerance to salicylate at 500 mg l⁻¹ and 1500 mg l⁻¹ but only produced 0.7 mg O₂ l⁻¹ h⁻¹ in the absence of pollutant. Chlorella sorokiniana resisted salicylate at 1500 mg l⁻¹ with the highest O₂ production in the absence of salicylate (26 mg l⁻¹ h⁻¹) closely followed by the Bolivian microalga (23 mg l⁻¹ h⁻¹) and Chlorella vulgaris (21 mg l⁻¹ h⁻¹). Selenastrum capricornutum and Anabaena catenula were completely inhibited by salicylate at 500 mg l⁻¹. When inoculated with Ralstonia sp. and supplied with salicylate, Chlorella sorokiniana had the highest removal rate (19 mg l⁻¹ h⁻¹), followed by the wild Bolivian strain (18 mg l⁻¹ h⁻¹) and Chlorella vulgaris (14 mg l⁻¹ h⁻¹).