Keystone microalgae species determine the removal efficiency of sulfamethoxazole: a case study of Chlorella pyrenoidosa and microalgae consortia

Abstract

In recent years, antibiotics pollution has caused serious harm to the aquatic environment, and microalgae mediated degradation of antibiotics has attracted increasing attention. However, the potential toxicity of antibiotics to keystone microalgae species or their microalgae consortia, and the impact of microalgal diversity on antibiotic removal need to be further studied. In this study, we investigated the removal efficiency and tolerance of five freshwater microalgae (Chlorella pyrenoidosa, Scenedesmus quadricauda, Dictyosphaerium sp., Haematoccocus pluvialis, and Botryococcus braunii) and their microalgae consortia to sulfamethoxazole (SMX). We found that the removal efficiency of SMX by C. pyrenoidosa reached 49%, while the other four microalgae ranged between 9% and 16%. In addition, C. pyrenoidosa, S. quadricauda, and Dictyosphaerium sp. had better tolerance to SMX than H. pluvialis, and their growth and photosynthesis were less affected. At 10 and 50 mg/L SMX, the removal capacity of SMX by mixed microalgae consortia was lower than that of C. pyrenoidos except for the consortium with C. pyrenoidos and S. quadricauda. The consortia generally showed higher sensitivity towards SMX than the individual species, and the biochemical characteristics (photosynthetic pigment, chlorophyll fluorescence parameters, superoxide anion (O2-), superoxide dismutase activity (SOD), malondialdehyde (MDA) and extracellular enzymes) were significantly influenced by SMX stress. Therefore, the removal of antibiotics by microalgae consortia did not increase with the number of microalgae species. Our study provides a new perspective for the selection of microalgal consortia to degrade antibiotics.

Unraveling the Role of Microalgae in Mitigating Antibiotics and Antibiotic Resistance Genes in Photogranules Treating Antibiotic Wastewater

“…14 Huang et al observed a diminished antibiotic removal performance in mixed microalgae media compared to single microalgae media, attributed to metabolic competition. 15 Therefore, MBGS formation with a proficient exogenous microalgal strain under a relatively low light intensity for antibiotic treatment could increase the system performance and efficiency. There is currently limited research on the fate of antibiotics and ARGs in MBGS systems.…”

“…In MBGS development, uninoculated BGS exposed to a stronger light promoted the growth of diverse microalgae colonies on BGS, , while microalgae-inoculated BGS under lower light conditions fostered a quasi-unicellular microalgal growth on MBGS, enhancing stability and nutrient removal . Huang et al observed a diminished antibiotic removal performance in mixed microalgae media compared to single microalgae media, attributed to metabolic competition . Therefore, MBGS formation with a proficient exogenous microalgal strain under a relatively low light intensity for antibiotic treatment could increase the system performance and efficiency.…”