Enhancing treatment performance of Chlorella pyrenoidosa on levofloxacin wastewater through microalgae-bacteria consortia: mechanistic insights using the transcriptome

The microalgae-bacteria consortia (MBC) system has been shown to enhance microalgae efficiency in wastewater treatment, yet its effectiveness in treating levofloxacin (LEV) wastewater remains unexplored. In this study, we compared the treatment of LEV wastewater using pure Chlorella pyrenoidosa (PA) and its MBC. The results showed that MBC optimized the removal performance of PA for LEV wastewater. The removal efficiencies of PA for LEV were 3.50 %-5.41 % while the treatment efficiencies of MBC were 33.62 %-57.20 %. The MBC system significantly increased microalgae biomass and extracellular polymeric substance (EPS) secretion, yet reduced photosynthetic pigment content compared to the PA system. At the phylum level, Proteobacteria and Actinobacteriota are the major bacteria in MBC. Furthermore, transcriptome reveals that the growth-promoting effects of MBC may be associated with the up-regulation of genes encoding glycolysis, citrate cycle (TCA cycle), and pentose phosphate pathway.