Molecular insights into synergistic bioremediation of sodium cyclamate by the Scenedesmus obliquus-Niallia nealsonii consortia: Efficiency, application, and mechanisms

Artificial sweeteners (ASs) are frequently found in aquatic environments and pose ecological risks comparable to antibiotics, prompting the urgent need for targeted ASs removal technologies. Microalgal-bacterial consortia is commonly applied for the remediation of pollutants (e.g., antibiotics, microplastics), yet their potential for ASs removal remains unexplored. Therefore, we hypothesize that microalgal-bacterial consortia may exhibit antibiotic-like removal effects on ASs in aquatic environments. Here, we validated this hypothesis using sodium cyclamate (CYC) as a representative ASs and successfully constructed an S. obliquus-N. nealsonii consortia capable of synergistically enhancing CYC removal by evaluating biomass production, photosynthetic activity, oxidative stress levels, and CYC removal efficiency. Under a 10:1 inoculation ratio (1 g/L, wet weight, S. obliquus: N. nealsonii), the consortia achieved complete removal of CYC (30 mg/L) through enhanced bioadsorption (129 %) and biodegradation (69 %) compared to monocultures. Meanwhile, the consortia demonstrated promising application potential in municipal wastewater and pig manure anaerobic digestion effluent treatments, achieving removal efficiencies of 27 % and 21 % for externally added CYC, respectively. Finally, transcriptomic analysis revealed that the consortia achieved synergistic and efficient CYC elimination by promoting heterotrophic metabolism in S. obliquus and enhancing the uptake and utilization of organosulfur compounds in N. nealsonii. This study provides a resource-oriented novel strategy for microalgal-bacterial consortia to treat wastewaters containing ASs.